Impronte specie aliene inglese

ALIENS IN THEIR OWN LAND Non - native species: responsibilities and solutions

Massimo Vitturi and Barbara Bacci

THE AUTHORS

Barbara Bacci Translator and wildlife enthusiast. Her work as volunteer and her studies in wildlife management brought her to collaborate with LAV on this report.

Massimo Vitturi Responsible for the Hunting and Wildlife sector within LAV, he's been a member of the National Board of Directors since 2009.

Vitturi often holds conferences on humane methods of wildlife control. He works with Italian and foreign veterinarians and biologists to perfect new methods for the management of wildlife respecting the well-being of the animals and the interests of the stakeholders involved.

Editor Peter Oswald

LAV thanks the Cariplo Foundation for the propagation of this Dossier

Contents 1 - The Invaders

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2 - The Invasion Process

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3 - Resident Aliens

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4 - Eradication and Control

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5 - Towards a More Humane Management of Allochthonous Species

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6 - Italy

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7 - Social and Financial Implications

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Š COPYRIGHT LAV VIALE REGINA MARGHERITA 177 - 00198 ROMA RIPRODUZIONE CONSENTITA CITANDO, ANCHE PER LE SINGOLE PARTI, LA FONTE: LAV 2013

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1. THE INVADERS “We are seeing one of the greatest convolutions of the world’s flora and fauna.”

Charles Elton, 1958

When we talk about invasive alien species (IAS) we usually refer to animals or plants introduced intentionally or unintentionally into a natural environment. The Convention on Biological Diversity (CBD), in its Conference of the Parties (COP) VI/23, defines “alien species” as a species, subspecies, or lower taxon, both animal and plant, introduced outside its natural past or present distribution. According to Richardson et al. (2010), alien species are “those whose presence in a region is attributable to human actions that enabled them to overcome fundamental biogeographical barriers.” Other researchers have a different view. Ned Hettinger (2001), philosophy professor at the College of Charleston in South Carolina, proposes a more flexible and comprehensive meaning for the term, defining nonnative as “any species significantly foreign to an ecological assemblage, whether or not the species causes damage, is human introduced, or arrives from some other geographical location.”

It is generally understood that when IAS start spreading they might become a threat to local species and damage whole ecosystems, destroying their biodiversity and causing the extinction of local species. Alien species can be harmful to autochthonous species in different ways: by competing over resources, such as light, food, water, and space, by predating on them, displacing them, parasitising them or by introducing new pathogens and parasites to which indigenous species are not adapted; and finally, by hybridising with local species, causing global homogenisation (McKinney and Lockwood, 1999). Alien species have important socioeconomic consequences for society. To estimate in probabilistic terms the percentage of an alien species becoming an invasive the tens rule is applied. According to this rule 10% of imported species become casual, 10% of these become naturalised and 10% of naturalised species have a negative impact (Williamson & Fitter, 1996). Thus, in reality only a very small number of introduced species eventually becomes established and has a negative impact on its new environment.

All invasive alien species share characteristics which facilitate their colonisation of new habitats, such as rapid reproduction and high growth rate, high dispersal ability, phenotypic plasticity—that is, the ability to adapt physiologically to new conditions—as well as the ability to survive on a varied diet and in different of environmental conditions. These characteristics, matched with the vulnerability of some ecosystems, speed up the process of invasion.

At present, there is a global consensus that IAS represent a danger. A new Strategic Plan was adopted by the COP 10 of the Convention for Biological Diversity held in Nagoya, Japan, in October 2010. Other international bodies, such as The International Plant Protection Convention (IPPC), the World Organization for Animal Health (OIE), and the International Maritime Organization (IMO), deal with the question of exotic species.

In Europe, however, there is no comprehensive European Union legislative instrument addressing the question of IAS, and Member States vary in the way they address the issue. Different legislative instruments addressing the question of IAS exist: the EU legislation (e.g., Council Regulation 338/97 (Wildlife Trade Regulation), Directive 2000/29/EC (Plant Health Directive), Veterinary Legislation, Council Regulation 708/2007 (concerning use of alien and locally absent species in aquaculture), Nature Directives (Directives 92/43EEC and 79/409/EEC, Habitats and Bird Directives), Water Framework Directive (2000/60/EC) and the Marine Strategy Framework Directive (2008/56/EC).

The Council of the European Union, in its meeting on Dec 19, 2011, covered the issue of IAS in its conclusions on the implementation of the EU 2020 Biodiversity Strategy. In the document the European Parliament called for the preparation of a dedicated legislative instrument by 2012, and for the inclusion of questions relating to the impact of IAS on biodiversity within the EU Plant and Animal Health Regimes. Furthermore, Member States should ratify the Ballast Water Convention to minimise the spread of IAS from maritime and inland water transport. The dedicated legislative instrument should cover all aspects relative to IAS, including their identification and prioritisation, control and eradication, management and implementation of their pathways following a risk-based approach and in a proportionate and cost-effective manner.

Risk assessments (RA) are employed by the different Member States to establish whether an organism is an IAS, and what course of action should be taken: prevention, control, or eradication. There is no EU risk assessment procedure, and each Member State defines its own based on two criteria: the obligation to conduct risk assessments for IAS in defined circumstances, and the existence of a standardised methodology for conducting such assessments.

The existing research projects on alien species are Delivering Alien Invasive Species Inventories for Europe (DAISIE), Assessing Large-scale Risks for biodiversity with tested Methods (ALARM), Increasing Sustainability of European Forests Modeling for security against invasive pests and pathogens under climate change (ISEFOR) and Vectors of Change in Oceans and Seas Marine Life, Impact on Economic Sectors (VECTORS).

Prevention, early detection, and a rapid response are the best way to minimise the impact of alien species. Prevention can be

5 implemented through stricter import regulations, by adopting more biosecurity measures, such as quarantines, for species which have been introduced.

species to a region; as it is not usually known exactly when a species was introduced, Rejmánek (2000) introduced the term “minimum residence time” (MRT).

KEY TERMS 2. THE INVASION PROCESS Alien species (synonyms allochthonous, foreign, exotic, introduced, nonindigenous, nonnative): Refers to a species, subspecies, or lower taxon, introduced outside its normal past or present distribution and outside of their natural dispersal potential; includes any part, gametes, seeds, eggs, or propagules of such species that might survive and subsequently reproduce.

Autochthonous species (synonyms indigenous, native): Refers to a species, subspecies, or lower taxon living within its natural range (past or present), including the area that it can reach and occupy using its own legs, wings, wind/waterborne or other dispersal systems, and therefore without human intervention, even if it seldom found there.

Biological invasions (synonyms bioinvasions, biotic invasions): Refers to events and processes by which a species, introduced by human agency through various introduction pathways into a new range, adapts and starts spreading into a region. It includes all aspects of adaptation: how species become established, reproduce, disperse, spread, proliferate, interact with resident biota, and have an impact over their new ecosystem.

Casual alien species (synonyms acclimatised, not established, adventive): These are alien species that occasionally reproduce in a new environment, but which eventually die out because they do not form self-replacing populations, and rely on repeated introductions. (CBD, 2000).

Eradication: This is the extirpation of all the individuals in a population or propagules of an invasive species.

Introduction: Refers to movement of a species, subspecies, or lower taxon (including any part, gamete, or propagule that might survive and subsequently reproduce) outside its past or present natural range. This movement may be intentional or accidental, by human agency, within a country or between countries.

Invasive Alien Species (IAS): Refers to an allochthonous species which has spread in its new environment and represents a threat to its biodiversity and/or for human activities, agriculture, has a negative impact on human health and has important socioeconomic consequences. Invasives often reproduce in large numbers and can spread over large areas quickly, thus expanding rapidly their new range.

Naturalised species (synonym established refers to plants, while animals are said to be naturalised): These are allochthonous species that form free-living, self-sustaining, and durable populations in the wild unsupported and independent of humans (IUCN, 2000, 2002; Richardson et al., 2000: Occhipinti-Ambrogi and Galil, 2004; Pyšek et al., 2004).

Para-autochthonous species: In Italy, this term refers to a species of plant or animal, nonnative to a certain environment, which was introduced and naturalised before 1500 (Genovesi, 2007). According to the Decree of the President of the Italian Republic, no. 120/03, these species may be considered autochthonous.

Pest species: According to Pyšek (2009) This is a cultural term applied to animals (not necessarily alien) occupying environments where they are not wanted and which have a detectable environmental and/or economical impact.

Residence time: Refers to the time since the introduction of a

“It is ironic to me to hear people of European ancestry accuse other organisms of being invasive exotics, displacing native species.”

J. L. Hudson, 1997, American seedsman

Alien species are at the core of both our food production and the very way we live. We inhabit all areas of the world, and we take different species with us wherever we go; for food purposes—like rice, maize, chickens, cows, sheep, etc.—to use in forestry and landscaping, or as biological control, for sport, or as pets. We can travel anywhere by plane in twenty-four hours carrying with us plants and animals, pathogens and parasites, which can in this way easily overcome natural barriers limiting their dispersal. As Charles Elton pointed out in his pioneering work on biological invasions in 1958, the most successful invasive species are the ones crossing major barriers thanks to their relationship with man. Not only we are the cause of the phenomenon of invasive alien species, though. The number of alien species will increase in line with the increase in shipping, air transport, and trade in different products (Bright 1998, Mack et al., 2000), as well as the progressive trend towards the elimination of protective measures in favour of free trade. At the same time, the growth in human population and development will continue to be the primary cause of biodiversity loss, due to habitat loss and fragmentation (Wilson, 1992) which, in turn, will continue favouring biological invasions (Hobbs and Huenneke 1992). Out of all the different plant and animal species introduced into a new area, an estimated 10% get established to the point of spreading and becoming a “pest.” (Williamson and Fitter, 1996). Even though only a very small percentage of organisms introduced into a new environment becomes invasive, some authors consider IAS to be one of the major causes of biodiversity loss, second only to habitat destruction (Wilcove et al., 1998; Wilson, 1992). Disturbed habitats are more vulnerable to biological invasions, but at the same time invasive species alter disturbance regimes in natural systems, exacerbating the effects of fragmentation and disturbance (Mack and D’Antonio, 1998). Other factors favouring invaders are lack of predators, great abundance of spatial and food resources (Orians 1986, Shigesada and Kawasaki 1997), and the presence of established pathways. This type of synergism results in a cycle of invasion, habitat loss and therefore more invasion.

Other factors can play a role in either amplifying or inducing the phenomenon of alien species. Climate change facilitates the spread of alien species, enabling them to survive in previously inhospitable areas. The global decline in amphibians has been blamed in part on chytridiomycosis, an infectious disease of amphibians, caused by the chytrid fungus, Batrachochytrium dendrobatidis. The emergence of the disease is due both to human transportation of infected frogs and to the spread of the fungus, which is favoured by global warming (Pounds et a.l, 2006).

In the past, species spread their ranges and colonised new habitats, sometimes as a result of natural events. On November 14, 1963 an eruption started southwest of Heimaey, in Iceland. By 1967, the islands of Surtsey and Jólnir were formed. Soon after the formation of Surtsey, plants and animals started colonising it: seeds reached the island through the sea, or through disper-

6 sion by the wind or by birds. A few weeks after the eruptions ceased the sea rocket, Cakile edentula, was already blooming.

During the first few years of the island’s life, scientists counted 170 different insect species. Since 1967, over ninety bird species have been observed in or around the island, and at least six of them breed on the island. Grey seals, Halichoerus grypus, have been breeding on the island since 1983. Marine life is varied and thriving. Vermeij (1991) points out that the breaking down of natural barriers – as a result of physical events, such as moving land masses or volcanic activity, changing environmental conditions, biological ones, or because of ecosystems separating– all allow species to move freely and invade new areas. While in the past these occurrences were limited, human agency is removing these natural barriers at unprecedented rates. The construction of the Suez Canal, for instance, has caused hundreds of marine species to cross over to the Mediterranean Sea from the Red Sea. Non indigenous species can colonise all habitats, but they are especially problematic when they become established on islands.

Due to their endemic and unique species, and given their geographic isolation, the lack of strong competitors and predators, as well as the availability of uncolonised niches, islands are more vulnerable to biological invasions.

And yet, exotics were once considered very differently from now.

In 1854, the first acclimatisation society was created in Paris. La Société Zoologique d’Acclimatation had as objective to promote the acclimatisation, domestication, and reproduction of exotic species considered useful or ornamental. More societies were soon founded—the American Acclimatization Society was opened in New York in 1871 with the aim to import European flora and fauna into North America. Acclimatisation societies spread to European countries, Australia and New Zealand. The introduction and spread of desirable nonnatives was actively encouraged.

Many species introduced for hunting purposes have become a serious threat to their new environments. In Europe, different species of deer such as the fallow deer, Dama dama, native of the Near East and introduced into the Mediterranean region in Roman times, are now considered invasive species to be eradicated.

In the XVII and most of the XIX century, in Italy, the boar was not widely distributed throughout the territory (Massei and Toso, 1993), even after a massive reintroduction. From the 1950s onwards populations of eastern wild boar coming from Hungary, Poland, and Chzechoslovakia were introduced for hunting purposes (Pedrotti et al., Banca dati ungulati, http://digilander.libero.it/urcalomb/Banca%20dati%20ungulati.htm). Compared to the endemic boar, the Eastern subspecies is bigger, capable of reproducing up to three times a year and bearing more piglets than the original subspecies. Although wild boars now cause serious damage to local crops and natural reserves, eradicating or otherwise controlling their population is not always taken into consideration because they are defended by the hunting lobbies. (http://www.giornale.sm/pesaro-i-cinghiali-sono-sempre-piu-unproblema-per-lagricoltura-ma-la-caccia-spietata-e-lunico-rimedio-possibile-71691/) European rabbits, Oryctolagus cuniculus, were introduced by British colonists into Australia in 1788 and later into New Zealand.

They reproduced successfully, have had a devastating effect on the local ecology, destroying vegetation to the point of causing erosion, and they also feed on crops, causing damages in the millions of dollars. Various methods of eradication have been used, with little success. Heedless of this lesson, when native populations of rabbits in the south of Europe were decimated by the Myxomatosis virus, hunters introduced the eastern cottontail, Sylvilagus floridanus. The eastern cottontail is a lagomorph introduced in the area of Pinerolo, in the Italian Piedmont, in 1966. Since then, the species has colonised plains and hilly areas, where it occupies ecological niches belonging to the European

hare, Lepus europaeus, which is experiencing a serious decline.

Not only the eastern cottontail displaces this native species, it also damages local crops, and is a carrier of dermatophyte fungi (M. canis, M. mentagrophytes and M. gypseum), which are transmissible to men. Thus, it is a possible source of infection for gamekeepers, hunters, and veterinarians (Gallo et al., 2005) The repeated introduction of new fish by anglers and the introduction of new invasive alien species and parasites in many fishing sites have caused hybridisation, decline in local species, and habitat destruction. In the 1970s, the Welsh catfish, Silurus glanis, native to central and eastern Europe, was introduced into several lakes for fishing purposes but has since colonised all aquatic ecosystems in Northern Italy. This fish is a formidable predator and it is drastically reducing the biodiversity of the waters it inhabits. A population census carried out in 1996 in the Tiber River shows the presence of nineteen exotic species, representing 57.6% of the total of species found in the river.

Many species have been introduced as ornamental animals or plants, as is the case of the American grey squirrel, Sciurus carolinensis, in Italy, or the ruddy duck, Oxyura jamaicensis. The ruddy duck was introduced into England in 1949 by Sir Peter Scott, a British ornithologist. Since then, the ruddy duck has spread to most of the Western Palearctic, further endangering the already vulnerable white-headed duck, Oxyura leucocephala, with whom it often hybridises. As a result, the Council of Europe has enacted an eradication plan for the whole region.

A very high number of invertebrate species have been introduced worldwide for biological control. However, according to research carried out by Roques, of the Institut National de la Recherche Agronomique (INRA), these species represent only 10% of the total number of alien species present in Europe. The other 90% has arrived as contaminants aboard airplanes or other transport, or with imported plants. The tiger mosquito, Aedes albopictus, native to Southeast Asia, is the most well-known example. The mosquito reached Europe through trade in used tires, and is a vector for many diseases, amongst them dengue fever, chikungunya disease, and Nile virus.(Source: http://cordis.europa.eu/fetch?CALLER=NEWSLINK_IT_C&RCN=29 063&ACTION=D) Exotic pets are constantly being released, whether voluntarily or involuntarily. Anthropophilic species are those which live in association with humans, such as the animals we raise for food or as pets, or species which depend on our style of life for survival; commensal rodents and their host-specific pests and parasites belong to this category. When some of these species escape and become feral they have higher chances of survival in their new environment and may act as invasives. Two kinds of parakeets, the ring-necked parakeet, Psittacula krameri, and the monk parakeet, Myiopsitta monachus, have established breeding colonies in urban areas of North America, Europe, Africa and Asia (Lever, 1987) and have now become a common site in many major cities throughout the world. The red-eared slider, Trachemys scripta elegans, one of hundreds of the world’s worst invaders (ISSG, 2006), is an exotic pet that has been repeatedly released in European waters. It now competes for resources with the native pond terrapin, Emys orbicularis, classified as Near Threatened on the International Union for Conservation of Nature (IUCN) Red List.

Other species, like the tiger mosquito discussed earlier, are not introduced intentionally but travel as unwanted passengers with cargo, as hull fouling, in ballast water, or inside transported plant materials, soil or related equipment. They are small organisms, usually insects, some of which can now be found globally (Nentwig, W. 2007) like the giant Asian huntsman spider, Heteropoda venatoria (Platnick 2006).

Fur farms are another important pathway of introduction of allochthonous species. Animals regularly escape these farms, or are released, and form feral populations. The best known example is

7 the South American nutria, Myocastor coypus, present in Europe and the Americas, or the East Asian raccoon dog, Nyctereutes procyonoides, spreading in the whole of Europe. Many European raccoons are infected with the roundworm Baylisascaris procyonis, which causes encephalitis in a variety of birds and mammals, including man. The South American nutria was both intentionally released and escaped from fur farms in North America, Europe, and Asia. It is presently distributed worldwide and causes serious harm by destroying river banks, dikes, and irrigation facilities through burrowing, besides damaging vegetation in the wet areas it inhabits. Considered one of the world’s one hundred worst invasive species it is often fought with a variety of methods.

Finally, zoological gardens, aquaria and oceanaria represent yet another pathway of introduction for alien species. Animals can escape enclosures, because of damage to boundaries or through waterways, or because of damage to the zoological structures due to floods, storms, or fires; and they can be accidentally released, or bought and then released (Hulme et al., 2008; Padilla and Williams, 2004, Fàbregas et al., 2010). Out of 140 alien bird species present in Europe, 27 have escaped from zoological gardens (Kark et al., 2009), and, more broadly, escapes represent to 6% of known causes of introductions (Genovesi et al., 2009). Of the many documented cases, Fitter (1959) points out that the presence in Derbyshire of the grey squirrel Sciurus carolinensis, and the red-necked wallaby, Macropus rufogriseus, is the result of a voluntary release from a zoo.

Native species too can become invasive, due to changes in the environment (Howard and Chege, 2007) such as habitat loss.

New pathways of biological invasions also come from our necessity for biofuel crops. Plants chosen as biofuel stock species, such as oilseed rape, Brassica napus, share many traits with highly invasive species: they are habitat generalists, are adaptable, have a high relative growth rate (RGR) and produce propagule early in their development, vegetative reproduction. To minimise impact biofuel crops are planted in disturbed habitats and marginal lands (Rajagopal 2008, Gopalakrishnan et al., 2008), but the risk of these plants becoming invasives remains great. African oil palm, Elaeis guineensis, is the second most traded oil crop in the world after soy. Oil palm plantations are one of the major causes of tropical rainforest clearance, and also have adverse impacts on food production and poor net carbon benefits; and the species has already become invasive in the Atlantic forest in Brazil (Howard and Ziller, 2008).

It stands out that the phenomenon of exotic invasive species is indissolubly tied to the way we live, to our agriculture, trade, travel. For every species we try to eradicate, many more are being introduced. The answer, often, lies in prevention.

3. RESIDENT ALIENS

“History shows that it is not only senseless and cruel, but also difficult to state who is a foreigner.”

Claudio Magris, Danubio

Nobody would argue that exotics sometimes cause great damage to their new environments, but is the idea of alien species a biased concept?

In the United States the controversy between mute swans, Cygnus olor, and trumpeter swans, Cygnus buccinatur, rages on. Introduced as an ornamental species to North America from Europe in the mid-1800s, the mute swan is considered a pest. Although they were first brought to America to live in city parks and estates, they are now thought to be a threat to humans, of whom they have little fear and whom they apparently someti-

mes attack. They are also considered to threaten other wildlife, displace native trumpeter swans, and destroy the wetlands they inhabit. Once common in North America, the trumpeter swan almost went extinct because of the trade in its meat and feathers.

Reintroduced into the wild in the 1900s, it is now thriving in restored wetlands. The two swans share the same habitats, feed on plant materials and small invertebrates, and are almost identical to the degree that a common concern is that trumpeters get shot by those same hunters who should keep the mute swan population in check. Mute swans can be shot and their eggs shaken or even covered in oil. In April 2012, the state of Michigan decided to eliminate 13,500 mute swans to reduce their population, estimated to be 15,500 birds. A lot of money goes into native trumpeter reintroduction programmes, and a lot of money is being spent on destroying mute swans.

In the 1990’s, the birth of a new discipline, “invasion biology,” brought about a terminology derived partly from common law and partly from military jargon. The new discipline somehow compared introduced nonindigenous species to a natural enemy.

Natives were associated with pure and natural, while aliens were damaging, aggressive, and quick to reproduce and displace the more desirable indigenous species. The stage had been set. In 1998, the European Environment Agency defined alien species as one of the main threats to Europe’s biodiversity. Since then, the dichotomy of native versus alien has been accepted by the public as well as the scientific and political world, with all the biases it carries. While native seems to evoke feelings of protection and nationalism and equals desirable, alien is perceived as the outsider, polluter, undesirable. The portrayal of invasive species by the press, or by biologists, is always meant to trigger repulsion, distancing people from the fate of those creatures. They are described as a “threat,” tolerant of poor and squalid conditions, aggressive, displacing native species or being the cause of habitat degradation, as highly fecund, and so on. This negative view of allochthonous species as harmful and to be removed pervades the society and the scientific world alike. Yet not all introduced species have a negative impact: certain populations have reached an equilibrium with indigenous communities (Chanin & Linn, 1980; Smal, 1988) or may be keeping another alien species under control (Nogales & Medina, 1996). Some species are evolving and becoming naturalised. A species may be classified as harmful due to its origins alone, rather than because it damages its present environment (Hone, 1994).

Some species such as the wild goat and the mouflon were considered autochthounous, but recently it was shown that they were introduced by man in the Neolithic. Masseti (2009) suggests that these species of ancient anthropochorous origin be considered cultural heritage. For this reason, they should not be eradicated but protected and studied as historic documents that can tell us a lot about how they survived and adapted to the environment, and about the history of man, who have used these animals for its process of colonisation.

Other species have a bad reputation. Rats, although considered the most harmful invasive mammals in Europe, were found to be less damaging than previously thought. The presence and abundance of seabirds on Mediterranean islands, most of which have been invaded by rats, are affected more by the islands’ physical characteristics than by rats. Some seabirds, shearwaters for instance, tend to choose sites inaccessible to rats for reproduction, such as deep limestone caves. Rats seem to influence directly only the presence of storm petrels (Hydrobatidae), which are the most susceptible to rat predation amongst the Procellariiformes (Ruffino et al., 2009).

Tamarisk shrubs, Tamarix spp., were introduced from Eurasia and Africa into the United States in the nineteenth century as ornamental species. In the 1930s, during a water shortage in eastern Arizona, central Mexico and western Texas, it was thought the

8 shrubs were using the precious resources of water left. During the Second World War they were defined “alien invaders” and the US declared war on them. For seventy years they tried eradicating them using herbicides and bulldozers. The shrubs were not eradicated and now they are the nesting place of choice of the endangered southwestern willow flycatcher, Empidonaz traillii extimus. Given their capacity to survive drought, high salinity, and erosion, these plants are beneficial in maintaining river bank environments modified by human use and presence (Davis, 2011).

When species move of their own volition we describe their movements as natural colonisations rather than biological invasions, and thus they are not perceived as threatening. Until recently, cattle egrets, Bubulcus ibis, were found only in Africa, southern Spain, and Portugal. Towards the end of the nineteenth century they had expanded their range to South Africa. In 1880 they were spotted on the Corantyne River, in West Suriname. By the 1930s they were present in Guyana and Suriname. In 1953 they were breeding in Florida. Soon they arrived in Argentina and in Canada. Now, they are present as far as New Zealand and in Europe as far north as England and Ireland. They are a common sight in cow pastures all over the world, from Texas to Italy. Due to their high rate of expansion and success in adapting to new environments, they are listed as an invasive species in the Global Invasive Species Database. Under “General Impacts” it is noted that, given their capacity to thrive in areas densely populated by other bird species they could, potentially, compete over nesting sites. It is stated as well that a number of articles indicate that cattle egrets do not appear to have an impact on native bird species. Furthermore, cattle egrets spend their days in the pastures where they feed on beetles and grasshoppers and occasionally pluck ticks and flies off the cows. They return to the nesting sites at night, sites they share with other herons who feed on fish and aquatic invertebrates.

Through which evolutionary process do alien species become naturalised?

According to Peretti (1998), “It is unclear how long a species needs to be established in a location before it is considered native.

Is a species ‘naturalised’ in 100 years, 1,000 years, or 10,000 years? The distinctions are arbitrary and unscientific.” And fourteen years later, there is still no agreement in the scientific world.

The idea of minimum residence time was first suggested by Rejmánek (2000), but it refers mostly to plants, with little agreement when it comes to animal species. Genovesi (2007) suggests five hundred years must pass for a species to become naturalised. In Italy, the term para-autochthonous species is used in this context, referring to taxa introduced and naturalised before 1500. However, as we have seen earlier, rats are not considered naturalised although they were introduced in Mediterranean islands as early as two thousand years ago, and in other islands, such as the New Zealand islands, about seventeen hundred years ago, traveling with the first navigators to reach those lands. Carthey and Banks (2012) argue that it is the ecosystem which signals that enough time has passed. They studied whether bandicoots, Perameles nasuta, were aware of the danger represented by dogs and thus avoided them. Dogs are closely related to the dingo, Canis lupus dingo, introduced around four thousand years ago in Australia. Dingoes are considered either protected species or pest species, depending on the area in which they are found. According to evolutionary theory, prey must learn to recognise and adapt to threats in order to survive. In Australia, bandicoots have been exposed to dingoes for thousands of years, while domestic cats, Felis catus, were introduced only about 150 years ago, and it is unlikely they realise the threat they represent. Therefore, bandicoots should recognize and avoid dogs, but not cats or other pets. The study established that bandicoots avoid gardens where dogs can be found, even when tho-

se dogs are inside the house, showing they do recognize them as potential predators, which makes the idea of system adaptation plausible.

Although there is no general agreement as to how many years are necessary for naturalisation to take place, the capacity to reproduce and spread are often an indicator. A small population of ashy-throated parrotbills, Paradoxornis alphonsianus, was spotted for the first time in Italy in April 1995, at the Brabbia Swamp Nature Reserve, near Varese. The presence of the small passerine, native to southwestern China and northern Vietnam, was attributed to accidental escapes from a local animal and bird trader.

In 1999 (Boto et al.) the parrotbills were considered naturalised, given their capacity to reproduce and self-sustain, to grow in numbers, and to spread outside the reserve. At present, a second allochthonous species closely related to the first, the vinousthroated parrotbill, Paradoxornis webbianus, is present and naturalised in the reserve and even hybridises with the first (Galimberti et al., 2009). The vinous-throated parrotbill also comes from the same areas as the ashy-throated and is again a result of accidental escape from the same trader.

Adaptation is an ongoing process, and it increases over time.

Establishing how much the immigrant organism has to have adapted to its new abiota is no linear matter. Ecosystems vary considerably and so does the amount of adaptation needed to survive in them. A suburban, human-degraded area might consist mostly of exotics because disturbed ecosystems are either more vulnerable or favourable—depending on the side we want to stay on—to biological invasions. This, of course, does not mean exotics cause deterioration, but merely that disturbance favours colonisation.

Can ecosystems be restored to the “equilibrium” they enjoyed before a biological invasion?

Herodotus’s (484-425 BC) observations on prey and predators and on the position of an animal in the food chain gave origin to the idea of balance in nature, the view that nature is harmonious, which is at the basis of a natural theology. This view persisted until Darwin caused havoc with his insight on evolution, but for a long time scientists went on to believe in balance, purity of species, and the idea that species live in integrated communities.

Ecologists have abandoned the idea that ecosystems are homeostatic and that nature is a stable-equilibrium system. On the contrary, they agree that ecosystems are dynamic and in constant evolution, occupied both by native species, the long-term residents, and by new introductions, the resident aliens. There really is no balance exotic species can upset. New, “novel” ecosystems, whose characteristics are mostly unknown, emerge all the time. Restoring an ecosystem to conditions present at some historical time, when the balance of nature is considered to have been right, is not feasible. What we must do is avoid further damage. Ecosystems, together with all their components, have always undergone changes, and different species have always gone extinct, but the rate at which these phenomena are taking place at present is alarming. In 1993, Wilson estimated that the current rate of species extinction due to habitat destruction was in the range of thirty thousand species per year. The increased movement of plants, animals, and diseases between continents, ozone thinning, global warming, toxification, fallout of radionuclides caused by bomb testing, removal of top carnivores, and the general degradation of nature due to a variety of anthropogenic factors—all are perilously increasing the rate of change of ecosystems. Cities, dams, and water withdrawals alter hydrology, sometimes beyond recovery. Our planet is being altered in unprecedented ways. Roughly half of the earth’s surface is significantly disturbed by humans, and half of that is dominated by humans (Hannah et al., 1993).

How to define which is the pristine natural state to be restored?

9 Undoubtedly, invasives and other disturbances degrade and pollute ecosystems, but how to restore them, or how to re-create a system resembling pre-disturbance? Restoring vegetation is proving a difficult task. Restored wetlands have less plant-species diversity than natural ones, with lower colonisation rates (Seabloom, van der Valk, 2003). Will these poorer habitats support the same animal species that lived there in the past, or aid in their recovery? In the Americas, where traditionally colonial Europeans are blamed for the degradation of local ecology, it is thought that Native Americans lived in harmony with nature.

Hence, some wildlife managers believe ecosystems should be recreated as the first Europeans found them.

This view is in contrast with how anthropologists and archaeologists alike believe that Native Americans caused the extinction of most of the Pleistocene megafauna (Chase, 1987). Indeed, humans have had a disruptive impact on the earth since they appeared and have caused species to become extinct wherever they have migrated to. J. Diamond (1989) points out that one-quarter of all bird species present in the New World went extinct just before or after European contact. Large mammals and flightless birds went extinct at the time humans arrived in North America, Madagascar, New Zealand, and Australia. Humans have been moving species on five continents for thousands of years. Heywood (1989) states that even in the Amazon rain forest it is possible to observe the impact of man. Lions, camels, elephants, and spectacled bears are only some of fifty-seven species of large mammals that went extinct in North America a few thousand years ago.

Many of the plants they fed on are still there and they could probably re-adapt to current conditions (Soulé, 1990). Yet, they would certainly be considered exotics.

The fragile ecosystems of the Mediterranean have been modified by human intervention for over ten thousand years. Archeological findings indicate that the first nonindigenous mammals were brought onto Cyprus as early as the eighth millennium BC. At that time, seafarers brought on board their vessels both domesticated and wild species. This is how predator mammals, insectivores, micromammals and ungulates (Masseti, 2009) reached many Mediterranean islands.

All these considerations call for a more moderate view on exotics, opposed to the policy of plain extermination. Wildlife that causes considerable damage, such as feral pigs, or rats, should mostly certainly be controlled and their populations kept in low numbers. This need not be done by means of cruel methods of eradication but using more humane techniques. In 1990, the conservation biologist Michael Soulé envisaged the birth of a new discipline, recombinant ecology or mixecology, which would study “the interactions within these new, biogeographically complex assemblages.” Recombinant ecology does not consider alien species as bad per se. On the contrary, it examines why some species mix better than others.

The Channel Islands of California provide an interesting example of the dynamicity of ecosystems and of subtle interactions between populations, as well as of the difficulties in choosing which equilibrium to re-establish. On these islands, the introduction of feral pigs, Sus scrofa, in the 1850s facilitated the colonisation of golden eagles, Aquila chrysaetos. Golden eagles prey both on piglets as well as on endemic fox species like Urocyon littoralis, with the result that three endemic subspecies are now threatened by hyperpredation by golden eagles. The decline in foxes has caused the increase of its natural competitor, an endemic skunk, Spilogale gracilis amphiala (Roemer et al., 2002). Foxes, which have inhabited the islands for the last twenty thousand years, are endangered by golden eagles, which before the introduction of feral pigs were only transients on the islands but now can sustain a large breeding population. The question of conservation, however, is further complicated by the fact that golden eagles, threatened in other places, are too to be protected.

4. ERADICATION AND CONTROL

Eradication and control The key points in the strategy to fight the threat of invasive species are • prevention; • early detection and constant monitoring; and • mitigation, eradication, and control.

Prevention relies on the implementation of effective preventative measures to minimise the risk of invasions. These measures range from stricter control on trade and monitoring of invasion pathways, to restoring habitats to make them less vulnerable to invasions.

Detecting a new invasive species and being able to assess whether it represents a threat allows the best possible method to manage such population to be chosen. If the aim is eradication, this is possible only when an invasive is detected early.

Mitigation consists in reducing a population or creating a new habitat for a species endangered by an alien species. Eradication is more drastic and can be carried out by killing or removing the unwanted animals. J.H. Myers (2000) defines it as “the complete removal of all the individuals of the population, down to the last potentially reproducing individual, or the reduction of their population density below sustainable levels.” As seen earlier, this technique can be used only in the early stages of the process of invasion, or on small and accessible islands. Moreover, it is costly, both logistically and financially. Once an invasive becomes established, control is the only option left.

Undesirable species may be eradicated and controlled through a variety of methods, sometimes employing one or more of them together.

Barriers deny access to unwanted animals. Fencing works for larger animals, such as ungulates, but also excludes smaller ones such as foxes, cats, possums, rabbits, stoats, rats, and mice. A successful example of fencing is found on Amsterdam Island in the Indian Ocean, where feral cows have been thus excluded from areas populated by breeding birds like the Amsterdam albatross, Diomedea amsterdamensis (Micol & Jouventin, 1995). Netting is used for smaller animals such as birds or crabs, but there are some for coypus and rabbits, and screening is adequate for insect control.

Biological control makes use of parasitism, immunocontraception, predation, or competition to decrease the survival rate of unwanted species. The introduction of predators to reduce the population density of exotic species has usually ended in failure.

Predators turn into invasives themselves, ignore the target prey and hunt local species, or have unexpected impacts on the environment. When Indian mongooses, Herpestes auropunctatus, were introduced in the West Indies to control rats, the rats become arboreal to escape the new terrestrial mongoose predator. As a result, rats preyed more on tree-nesting birds, while mongooses began to prey on ground birds (Seaman, 1952).

The presence of alternative prey is now a well-known factor in the failure of some eradication projects. Let’s examine the case of Macquarie Island, where the introduction of rabbits, which took place when cats where already present, had a negative impact on the bird population. The number of birds present could in fact support only a small cat population, but the arrival of rabbits provided an alternative prey they could feed on during the winter, allowing the cat population to expand. Ten years after the introduction of rabbits, cat hyperpredation of birds caused the extinction of three different bird species (Taylor, 1979a).

Introduced species often spread beyond control, which is what

10 happened with the Indian Myna, Acridotheres tristis, introduced in Hawaii for the control of Fall armyworms, Spodoptera frugiperda, or in Melbourne where they were meant to control insect pests in market gardens. To consider how easily predator introductions can backfire, we can look at what happened in Jamaica.

In an attempt to control rats damaging their sugarcane crops, farmers introduced ants, Formica omnivora. Rat numbers were not reduced and the ants spread out of control, so they introduced marine toads, Bufo marinus, to control the rats. Again, toads turned into a problem themselves, and Indian mongooses were introduced to control both toads and rats. But they preyed instead on native birds, endangering them.

Competition is achieved by introducing a superior competitor to reduce the undesired population. Arctic foxes, Alopex lagopus, were introduced in the Aleutian islands in the early 1800s for fur farming. Due to the Arctic foxes’ devastating impact on seabirds, it was decided to eradicate them by introducing sterilised red foxes, Vulpes vulpes. A few sterilised red foxes were released on two of the smaller islands when there were no breeding seabird colonies present—larger islands would have required too many individuals to make the technique possible. Arctic foxes disappeared from the islands, but the red foxes also preyed on local birds (Bailey, 1993).

A different kind of biological control is achieved through pathogens (viruses and bacteria) used as lethal agents to control populations. A few examples of such agents are Salmonella spp. used for the control of rodents; myxomatosis and rabbit haemorrhagic disease (RHD) against rabbits; and feline panleukopenia (FLP) against cats. It is understood that neither predators nor pathogens (Bell, 1995) will completely eradicate a species, making the use of further measures necessary. Microbial insecticides are another method of biological control.

Finally, immunocontraception uses a vaccine to cause the immune system to attack its own reproductive cells, making the individual sterile. Considered the most ethical of all methods, it will be explored more in depth in the next chapter.

Biocides include insecticides, herbicides, rodenticides, and poisons. Rodenticide anticoagulants, used extensively to control, amongst others, rats, cats, and rabbits, work by altering the normal blood-clotting process. Anticoagulants have been used against rats worldwide, and resistance to these substances was first noticed in Europe in the 1960s and in the Unites States in the 1970s (Meehan, 1984; Jackson, Ashton et al., 1985). A new series of anticoagulants called second generation and third generation have been developed since. Second generation poisons are far more toxic than the first, are usually lethal after only one ingestion, have a longer elimination half-life, and are effective against warfarin-resistant rodents. Difenacoum, brodifacoum, and bromadiolone are in this group. Anticoagulants are harmful to a large number of animals: they accumulate in the stomachs and livers of wild carnivores, killing them. Polecats, barn owls, and red kites (Newton et al., 1990; Shore et al., 1996; Gillies & Pierce, 1999; Carter & Burn, 2000; Carter & Grice, 2000) are amongst the recorded nontarget fatalities. Fatal secondary anticoagulant poisoning has caused the death of red foxes, owls, buzzards, kites, and corvids (Newton et al., 1990; Proctor, 1994; Berny et al., 1997; Shore et al., 1999; Stephenson et al., 1999), as well as domestic dogs and cats. The risk to nontarget species can be lessened by capturing the animals to be protected and releasing them once the eradication programme is over. This is, however, possible only in a few situations, it is a very costly solution, and it requires manpower.

At present, other rodenticides such as diphacinone, which has a shorter tissue residue half-life, are being researched as alternatives in island eradications to reduce the risk of secondary poisoning.

Non-anticoagulants include compounds such as alpha-chloralose, a tranquillizer which acts by retarding metabolic processes. It can be used to kill mice and small rodents, causing death by hypothermia. Calciferol may be used on rats by overdosing, causing death by kidney failure within three to six days of ingestion (Meehan, 1984). Carbon dioxide, used against burrowing animals, causes death by asphyxiation. The length of the list speaks for itself: Alpha-naphthylthiourea (ANTU), arsenate, bromethalin, carbon disulfide, crimidine, fluoroacetamide (1081), formaldehyde, gophacide, hydrocyanic acid, lindane, methyl bromide, norbormide, phosphine, pyrethrins, pyriminyl, reserpine, scilliroside, sodium monofluoroacetate, strychnine, tetrachloroethane, thallium sulphate, zinc phosphide.

Habitat management modifies the environment to make conditions less favourable for invaders. In agricultural ecosystems, adding diversity can provide alternative food, nectar, or shelter in the form of noncrop plants grown together with crops. Another possibility are artificial structures. Supplying nesting and roosting boxes for birds—both songbirds and owls—and bats increases their numbers and provides natural insect and rodent control, and at the same time reduces the use of pesticides.

Trapping. It is used for rodents, cats, mustelids, mongooses, rabbits, hares, possums, and other animals. It is more effective with carnivores. There are many kinds of traps in existence, comprising both harmful and harmless versions. In spite of new designs, leg-hold traps and snares—both widely used—result in high nontarget captures. Animals caught in these traps often die a slow death, and some animals chew their own limbs off in an attempt to escape. To reduce nontarget captures, less-damaging trapping methods can be used to allow for the release of the trapped animal: foot-hold snares, stops in neck snares and foot-hold traps with padded jaws. In reality these traps, although approved by the Agreement on International Humane Trapping Standard, can still cause severe injuries. And the suffering caused by the stress of being trapped, maybe for days, is still very high. Cage traps are equipped with a system permitting the animal to enter, but not to exit. Birds can be captured with mist nets, which cause no harm if expertly employed.

Shooting. Considered a very efficient method to eradicate herds of large ungulates, it has been used against various species of birds and mammals. It is often employed in conjunction with other methods, such as helicopters, dogs, or judas animals. This last technique is effective with large, highly social vertebrates A feral animal, such as a goat, is fitted with a radio collar and used to locate the herd. The animals are then destroyed by shooting from helicopters, or from the ground, or they can be trapped and taken elsewhere.

Other harmful methods employed to control wildlife are hunting with bows or dogs, explosives, electrocution, drowning, burrow collapse, injection of gases, and preventing lactation to kill milkdependant young (Littin & Mellor, 2005).

Is eradication effective?

Removing a species from an ecosystem, whether it is an established alien or a native, will have consequences, some of which are undesirable. Careful studies realised before the enactment of the project will help predict some of these consequences, but each attempt at eradication is like a new experiment which could yield unexpected results not predictable by earlier programmes, even successful ones. On planning eradications, our ability to successfully manipulate populations and complex systems should not be overestimated (Jamieson, 1995). Ecosystems are dynamic, and relationships between populations of different species change over time. Plus, it should be noted that animal populations are subject to periodic fluctuations, and the impact

11 of invasives may vary with seasonal or environmental conditions or with population density. The interactions between native and nonnative species create complex links depending on the use of available resources, competition, and predation. In many cases, the removal of invasive species has caused what is known as a trophic cascade effect rather than the recovery of the ecosystem (Zavaleta et al., 2001). Removal of a single species, herbivore or predator, often results in the ecological release of a second species, plant or prey, previously controlled by the removed species (Zavaleta, 2002).

Sometimes, the success of an eradication is defined solely in terms of the absence of the target alien species, and does not take into consideration the response of the invaded ecosystem.

Eradicating a species does not bring the whole system back to pre-invasion equilibrium, nor does it eliminate the modifications the invader brought to the system. Towns (2008), studying the eradication of Pacific rats, Rattus exulans, from islands around New Zealand, found that ecosystem recovery was scarce and slow, because it was limited by the reduced number of native species remaining. In this case, reintroduction of seabirds is needed to restore seabird trophic interactions. Secondary effects of eradication include trophic cascade, mesopredator release, and the Sisyphus effect.

Trophic cascades take place when changes in the distribution of predators affect the abundances of other species across lower levels in the food web. The dingo, considered an invasive species in Australia, is an apex predator, albeit an alien one. Its removal has allowed the increased activity of herbivores such as the kangaroo, and of the red fox, Vulpes vulpes, itself an exotic mesopredator, causing both the loss of grass cover and the higher predation of small native mammals (Letnic et al., 2009). Reintroducing and maintaining a constant population of dingoes would benefit local mammal populations (Letnic et al., 2009), indicating that an alien species can assume a functional role as a key predator.

A related theory, the mesopredator release hypothesis, holds that reduced abundance of top predators results in increased abundance or activity of smaller predators (mesopredators) with detrimental impacts on the vegetation and on the prey of the smaller predators (Crooks & SoulĂŠ, 1999). Eradication of cats from islands, for instance, should be done together with the removal of their introduced prey, whether herbivores, omnivores, or carnivores. This, however, is no guarantee of success: rat eradication on Bird Island, in the Seychelles, caused the spread of the nonindigenous crazy ant, Anoplolepis longipes, which is now a threat for breeding sooty terns, Onychoprion fuscatus, and the native skink Mabuya sechellensis (Feare, 1999). Macquarie Island is yet another example of how cat eradication was detrimental to the local fauna. In 1878, rabbits were introduced to the island, but their numbers were kept at bay by cats, introduced sixty years earlier. Both species were detrimental to the island environment, rabbits because of extensive grazing and cats because of hyperpredation, resulting in the extinction of two local flightless bird species. In an attempt to eradicate rabbits, the myxoma virus was introduced yearly. When the rabbit population decreased, it soon became clear that cats were switching their prey of choice and targeting seabirds. In 1985, a cat eradication programme was started, and the last cat was shot in 2000. The rabbit population exploded, and complex vegetation communities were transformed into short, grazed lawns or even bare ground (Bergstrom et al, 2009).

Sisyphus, a figure of Greek mythology, was condemned by the gods to the futile task of forever pushing a boulder up a mountain, only to see it roll down again. In ecology, the Sisyphus effect occurs when the removal of an alien species results in the unexpected spread of another alien species. The eradication of goats and pigs from Sarigan Island, one of the Mariana Islands, caused the spread of the exotic vine Operculina ventricosa ,

which, within a few years, was suffocating the recovering vegetation.

Finally, the risk of reinvasion is becoming more real as more time has elapsed since eradications that were previously considered successful. Upon examining eradications of rats conducted on New Zealand islands or in the Seychelles, Clout (2007) found that after about ten years the possibility of reinvasion by rats is very high (HISTOGRAM). Furthermore, concerning inshore islands, he surmises that reinvasion is inevitable (Clout, 2008), as the animals can reach them by swimming.

Nevertheless, where possible, eradication remains the method of choice in ecology and is preferred to containment, which is aimed at limiting further spread of the unwanted species, or control, whose objective is reducing the presence of invasives.

Although a number of attempts at eradication in small areas have been successful and have benefited native biota, most eradication programmes, especially when aimed at well-established species, have a high failure-to-success ratio. Moreover, these programmes are costly, require much manpower and resources, and can be dangerous to the environment and to nontarget species.

Is eradication humane?

Most of the eradication techniques employed are extremely cruel and cause suffering to both target animals as well as to other animals that accidentally fall victim to them. Often, one method is not sufficient to ensure the complete removal of the target alien species, and therefore a combination of techniques is employed at once, for long periods of time.

Cage traps cause fear and stress. When the trap closes on the animal’s leg, it can cause wounds, cut tendons and ligaments, as well as break bones. Often, the animals caught in the traps chew off their own limbs to escape, and even when they do not, struggling will result in further injury. Death occurs days later by dehydration, blood loss, hypothermia, or predation by other animals, the victims conscious, in fear, pain, and distress. According to Iossa (2007), most killing traps in use today fall below the standards of animal welfare. Both killing and restraining traps used for mammals are effective when tested in compounds, but not in the field. Moreover, tested animals are anaesthetised and therefore show different responses compared to the animals caught in the wild.

In their study on the humaneness of rodent control, Mason and Littin consider a method humane when it causes the least number of symptoms before inducing unconsciousness and death, and which has no lasting ill effects on surviving animals. Inhumane methods cause severe and/or prolonged pain or distress, and leave surviving animals ill or disabled. Not surprisingly, their findings indicate that most methods of rodent control are inhumane and they are applied with little consideration for the welfare of the animal. More humane methods, such as snap trapping, electrocution, cyanide gassing, and alpha-chlorase, as well as exclusion and elimination of food supplies and a place to hide and nest, should be adopted instead. Anticoagulants such as brodifacoum, one of the most widely used rodenticides, causes a slow and agonising death. Death can occur within a day (Gill et al., 1994; PSD, 1997; Littin et al., 2000) but it can take as long as four to eight days. Furthermore, it leaves sublethally poisoned individuals ill for long periods of time.

The definition offered by Fraser (1996) of humane shooting requires that the animal be shot in the head at close vicinity. Most animals are not shot in such a clean way and do not die a quick death. Wounded animals can suffer acute and chronic damage from infected wounds, and dissociative and/or anxiety disorders.

Moreover, wounded animals cannot keep up with their group, nor feed, drink, or escape undesired situations.

12 Even when eradication could yield positive results, its costs in terms of suffering for the animals, and the growing hostility of the public towards these techniques makes research for new, ethical methods a priority. The complete eradication of feral cats from Marion Island, in the Southern Indian Ocean, is considered by some a success, by others an abhorrently cruel programme. To completely remove all cats from an island measuring 115 square miles (290 square metres), inhabited by no more than 2,300 cats (van Aarde, 1980), it took biologists nineteen years and multiple eradication methods. The project, started in 1974 and concluded in 1993, was divided into seven different stages. After a preliminary study, the ad hoc Task Group on the Extermination of Cats and Mice on Marion Island chose to use biological control by means of the feline panleukopenia virus. Cats were live trapped and then held in cages on the island to serve as future carriers for the disease. In 1977 the disease, meant to be only a primary control measure, was released through aerial spraying. After an initial decrease in numbers, the population rebounded and in 1981 a three-year hunting programme was enacted. Hunting by shooting and using dogs was combined with trapping with gin traps, considered to be one of the most cruel and harmful traps.

Many nontarget species were caught in gin traps, amongst them Salvin’s prions, Pachyptila salvini; subantarctic skuas, Catharacta antarctica; lesser sheathbills, Chionis minor; rockhopper penguins, Eudyptes chrysocome; and many more. Finally, a poisoning programme using sodium monofluoroacetate, compound 1080— which had previously been rejected due to its impact on birds— finished off the feral cat population. The last individuals were trapped in July 1991.

Such unwarranted cruelty is not necessary, not even to successfully eradicate an animal many biologists consider to be one of the most detrimental introduced species, especially on islands.

Cats were removed from San Nicolas Island, California, without unnecessary suffering and with the collaboration of the Humane Society of the United States. The study, initiated in June 2009 and concluded in February 2010, tried to make use of nonlethal methods: altered padded leghold live traps and feline-detection dogs. To capture as many cats as possible alive, spotlight hunting was used only in areas where trapping did not work. Fifty-seven feral cats were captured and transferred to a sanctuary in California

• They are mostly inhumane and cause unnecessary suffering, both to animals and to people concerned about their wellbeing.

INSERT

• They are often counterproductive (secondary effects, negative impacts on the environment.

Interview with Pedro Luís Geraldes Pedro Luís Geraldes is working on a LIFE (Safe Island for Seabirds) project organized by the RSPB. It is financed by the European Community, and its partners are the local city hall, the Portuguese BirdLife Partner SPEA. The aim is to eradicate rats and keep under control cats present on the island of Corvo, in the Azores, as well as recover natural vegetation by reintroducing endemic plants.

Corvo Island is the smallest Island of the volcanic Azores archipelago. It measures 17.13 square kilometres (7 sq miles), and is home to about 500 people. Agricultures occupies about 17.5% of the island surface. It’s served by planes (Corvo airport), and ferries. The Corvo Nature Park covers the Protected Area of Caldera of Corvo and the Protected Resource Area of the Coast of Corvo.

Like many other islands, Corvo has its share of human-introduced invasive species: a variety of plant species, rodents, cats, dogs, sheep, and goats. The breeding population of seabirds present on the island has decreased, possibly as a result of predation by cats and rats.

At the moment, the team is carrying out a preliminary research.

In 6 months from now it will present a report saying whether eradication is feasible, what is the status of seabirds and what

are the solutions to the problem of predation of seabirds by rats, mice, and cats.

All the inhabitants live in Vila do Corvo, and the rest of the island is destined to cattle and agriculture. Many seabirds reproduce on the island: Cory shearwaters, little shearwaters, and other procellarids, amongst which is the storm petrel. Seabird colonies are located on vertical cliffs up to 500 m. tall, and are therefore inaccessible, so recording devices, motion detection sensors, etc. are employed to study bird behavior. Most of these birds breed in places cats and rats cannot reach, but some do not and are exposed to predation.

The team is working on public awareness, teaching the importance of seabird colonies, of managing waste –promoting recycling -, of neutering cats and keeping them under control. The team carried out a spay and neuter project which lasted about 3-4 months, and was able to neuter and chip 90% of the cats present on the island. Local authorities have been asked to take over from there, as there are still an estimated two hundred strays.

In the past excluder fences like the ones used in New Zealand were employed to control rodents. The fences allowed to create a small reserve free of predators around the breeding colonies. For many months no rats or mice entered the area, but they eventually got it through a hole. The team is studying rodent density, peaks in the population, habitat interactions, the impacts on birds, the percentage of birds killed per year, how breeding success is affected by the presence of rats and cats.

The project was started in 2009. Results obtained that same year showed that rats represented an alternative prey to birds for cats. In the absence of rats, cats prey more on shearwater chicks.

The team is open to non traditional control methods, such as fertility control. But, we need to compare cost and manpower for each method. And, if it’s possible, consider how it should be done, and compare it with other solutions.

SUMMARY • Methods of eradication are highly controversial.

• They can be just as costly as or even more so than the expenses caused by the species they want to remove.

• They are seldom as effective or as final as they initially promise.

5. TOWARDS A MORE HUMANE MANAGEMENT OF ALLOCHTHONOUS SPECIES

“Man’s highest duty is to protect animals from cruelty.”

Emile Zola

“Man is the measure of all things.”

Pythagoras

Ethical implications Although a large amount of research has been carried out on how to fight alien species, the question of their welfare—and the suffering inflicted by methods of eradication and control—has been mostly overlooked. This is the reflection of a more general

13 trend. In Europe the Bern Convention, in its recommendations on alien terrestrial vertebrate, states that methods of eradication should be selective, ethical, without cruelty, and consistent with the aim of permanently eliminating the invasive species. At the same time, it allows exceptions for conservation or management reasons. The truth is that wildlife species, once labeled as pests, do not have any legal protection and no regard is given to their welfare.

In more recent years, some of the cruelest methods of killing wildlife have been under public scrutiny. In Europe, this has led to the banning of leghold traps and inhumane poisons such as arsenic and strychnine (Litton & Mellor, 2005). In some cases, public outcry has been beneficial to both the targeted species and to research. In New Zealand, possums, Trichosurus vulpecula, introduced in 1837 to establish a fur industry, have become one of the major threats to native forests and birds and contribute to spreading bovine tuberculosis. In 1940, New Zealand started eradicating possums using a variety of poisons, including sodium monofluoroacetate, called 1080, and leghold traps. Concern over the humaneness of these methods led to research on new and more humane methods. As a result, international standards for trap efficacy and humaneness have been developed, and pest control managers now employ different kinds of traps which cause less injury. Not only New Zealand now has different standards, which consider the welfare of possums, but the International Union for Conservation of Nature has suggested the creation of a single international standard for traps.

Mammal and bird eradication programmes are attracting more attention worldwide, due to employed methods having a profound effect on the targeted species’ welfare (Thiriet, 2007; McEwen 2008; Warburton and Norton 2009). Animals, be they considered pests or pets, experience pain in equal measure; public concern for “pests” as sentient animals is growing worldwide. This phenomenon is paralleled by an increased interest and involvement by NGOs and animal welfare organisations (Littin & Mellor, 2005; Schmidt, R.H. 1989; de Boo, J., Knight, A., 2005).

The public should be fully informed about eradication programmes, and its costs, whether ethical or not, should be clearly defined in order to justify undertaking the programme. The methods chosen should cause the least harm. Targeted animals should not be unduly portrayed in a negative light to gain support. Avoiding the suffering of target and nontarget species should be a priority.

According to Peter Singer’s (1990) utilitarian philosophical point of view, the benefits of eradication must outweigh the ethical costs. The ethical costs represented by the unpredictability of the results of these programmes, their secondary effects, and non-

target animals falling victims to them do not justify the suffering inflicted. Failed eradications are common enough to be a real concern. In all these cases, costs have been huge both in terms of finances and in suffering of the animals killed, but there have been no benefits. Looking at various studies carried out in New Zealand, we learn that in rat eradication there, there have been 159 successful programmes, with an 8% failure rate, which is 15 cases; for mice the figures are 30 successes with 19% failures (seven cases); for goats, 120 successes with 8% failures (ten cases); for feral cats 79 successes with 18% failures (two cases); and for rabbits the number of successful eradications are 17 with 11% failures (two cases) (Nogales, 2004; Campbell and Donlan 2005; Clout and Russell, 2006; Howald et al., 2007). In all of this, however, we do not know what the post-eradication conditions of the islands are and whether the term success refers only to the complete removal of the animals or to the recovery of the ecosystem.

The ethical decisions we make depend on our own set of values, which are a product of our culture, religion, beliefs, intuitions, upbringing experiences, and education. Science is not free of prejudice; both the public and scientists alike are imbued with their own culture and beliefs. While the welfare of animals belongs to the scientific realm, the way each one of us interprets humaneness and justifies the treatment of animals is more personal and philosophical.

The question of animal welfare is an important point in the management of so-called pest species. Although the reaction of the general public may vary considerably depending on the species targeted, the trend towards a stronger protection of animals’ rights is not a reversible process and cuts vertically through society. Scientists and animal rights supporters need to find common grounds to discuss the issue and find a solution acceptable to both parties.

Although conservation biologists and animal rights supporters both share a concern for animals, the first view them as assets, while the second perceive them to be sentient beings. Conservation biologists want to protect, preserve, and restore species and whole ecosystems through scientific means, regardless of the pain and distress these methods inflict on the targeted animals.

They often accuse animal welfare activists of being cynical about native species while worrying only about pests, or of becoming sentimental about feral cats, squirrels, foxes, and other animals considered cuddly and cute. However, eradication programmes do not harm target species alone, but also nontarget animals (Cowan, 1992). These projects can last for years, during which hundreds or thousands of animals are exterminated with great suffering.

Table 1. Largest islands where eradication was deemed successful.

Feral cows were eradicated only on part of the island, while the rest of the population was managed by exclusion.

Mammal species

Island and country

Size (km2)

Arctic fox Black rat Brushtail possum Brush-tailed rock wallaby Cat

Attu, Alaska, USA 905,8 St Paul, F 8 Rangitoto-Motutapu, New Zealand38.5 Rangitoto-Motutapu, New Zealand38.5 Marion, Sub Antarctic 190

Cows Goat Mouse Norway rat Pig Pacific rat Rabbit Red fox Sheep

Amsterdam, Indian Ocean San Clemente, California Enderby, New Zealand Langara, Canada Santiago, Galapagos Kapiti, New Zealand Enderby, NZ Dolphin, Australia Campbell, New Zealand

55 148 7.1 32.5 584.6 19.7 7.1 32.8 112.2

Method shooting and trapping poison poison, trapping, dogs poison, trapping, dogs biocontrol, trapping, shooting, poisoning shooting Shooting, trapping poison poison shooting, dogs poison poison poison shooting

Estimated number (years) 373 8-12000 21000 12500 2790+ 1124

Operation duration eradicated ?

3 8 8 19

1059 30000 ?

3000 19210 ? ?

30 ?

2 19 3 <1 27 <1 3 10 21

14 Adapted from Courchamp et al. (2003) Mammals invaders on islands To animal rights advocates, cruelty is not an option, and the methods used by biologists are considered both unethical and increasingly illegal. Animal rights supporters share the view brought forward in the eighteenth century by Jeremy Bentham, where the question is not: “Can they reason?” nor, “Can they talk?” but, “Can they suffer?” Animal rights supporters want to reduce animal suffering in general. While biologists are concerned about quantitative results, animal welfare activists worry about the individual fate of the animals.

What is a humane method of wildlife control?

Present models for vertebrate eradication consider safety, costs, feasibility, efficacy, availability, timing, weather, biology, and labour requirements. We ask that animal welfare be incorporated into the decision model, as it should be already (Schmidt, 1989).

The humaneness of a method of eradication depends on the suffering and distress it causes, how long the pain lasts, and how many animals are affected (Gregory et al., 1996). Along with Litton (2004), we should minimise the harm we cause animals, and research more humane methods. Besides, resorting to euthanasia should be taken into consideration more often.

Fisher (1998) lists a few common sense views that should always be taken into consideration: • “Animals are sentient beings, therefore it matters to them how they are treated; • We are responsible for animals within our care; • Animals should never be hurt, unless it is absolutely necessary; • If there are less painful ways of treating animals then they should be used; • Some harms should be prohibited, regardless of their benefits.”

The increasing importance of animal welfare is driving scientific research towards more humane methods of control, but there is an urgent need for a specific animal welfare policy on wildlife.

Existing laws aim to protect people and biodiversity from the impact of invasive species, but what are the legislative obligations, in Italy and in the EU, that aim to reduce and avoid inhumane methods of control of wildlife, minimising their suffering?

Humane alternatives for the control of feral animals Nonlethal methods of control of alien species exist and can be employed with success. Devices such as fencing, electric fences, or wires to prevent access to vertebrates, or chemical repellents against birds, rodents, insectivores, and ungulates are less harmful and avoid agricultural damage. Live capture traps, fertility and breeding controls should be employed whenever possible. All of the above methods can be used together with other measures.

In 2005, a project of eradication of feral cats on Pianosa, part of the Tuscan Archipelago, was carried out without the use of cruel methods. The cats were trapped with the help of volunteers and taken from Elba, where they were neutered and released near local cat colonies. In 2000, at the Melbourne Royal Botanical Gardens, animal rights activists blocked an attempt to cull a colony of grey-headed flying foxes, Pteropus poliocephalus. In 2002 a new programme was enacted, which resulted in the attempt to relocate the flying fox colony with the aid of acoustic deterrents and a number of individuals being moved to the relocation site.

The colony relocated not to the designated site, but to different ones, and finally settled in Yarra Bend Park, in the Melbourne suburb of Kew, where they are now allowed to stay.

Perhaps the real problem lies in the fact that to conservation biologists, economic considerations are more important than ethical and social ones. An eradication plan based on shooting is less expensive than the same plan based on live trapping and relocation, and is thus more probable that it will be approved by politicians. At the same time, not taking into consideration the welfare of the animals targeted will trigger public opposition, endangering the public image of the politicians supporting such plans. The failure of the project of eradication of the grey squirrel, Sciurus carolinensis, started in April 1997 in Piedmont, was caused by the opposition of the general public and of animal rights organisations. Only through cooperation between conservation biologists and animal rights advocates can a solution be achieved. A plan based on noncruel methods will enjoy more public support and will have more chances of being successful in the long run. It will, in fact, result in less financial expenses.

Fertility control Fertility control is perhaps the most humane and effective method for the management of wildlife populations. This technique offers many advantages over more traditional methods of removal. It is effective because it results in the constant decrease of the population. Since it is designed to cause no suffering, it is ethically acceptable. Not making use of poisons has less impact on the environment. Being species specific, it does not affect other species. Virus-vectored immunocontraception is self-disseminating and can be used to manage large areas at very low cost.

Fertility control can be achieved by mechanical and surgical techniques, endocrine disruption, and immunocontraception. Surgical techniques require capturing the animals, which makes the method too costly and impossible to apply to most wildlife species. Endocrine disruption requires implanting steroidal and nonsteroidal hormones to disrupt hormonal regulatory functions.

Immunocontraceptive vaccines trigger the response of the immune system and immunise the animal against proteins such as egg coat proteins or sperm proteins, or a hormone such as gonadotropin-releasing hormone (GnRH), which is needed for reproduction.

Some of these vaccines can be administered by remote delivery.

This technology uses a compressed-air powered rifle that delivers a bio-absorbable bullet or dart carrying the vaccine. Viral, bacterial, and microbial vectors have been studied to deliver vaccines to different wildlife species. The theory is that porcine zona pellucida (PZP) or GnRH, which causes the inhibition of fertility, could be engineered in a nonpathogenic virus that could then be delivered to target species (Kirkpatrick, 2011). The vaccine PZP is derived from pig eggs. Once administered, it stimulates the animal’s immune system to produce antibodies. These bind to sperm receptors on the zona pellucida of the animal’s eggs, blocking fertilization (Paterson & Aitken, 1990).

When an individual is infected by virus-vectored immunocontraception (VVIC), its immune system attacks its own reproductive cells, making the animal sterile. Individuals are infected through a gamete protein triggering the immune response: the antibodies produced bind to these proteins and block fertilisation (Bradley, Hinds & Bird, 1997). VVIC uses a species-specific virus to spread this vaccine through a population by placing the gene encoding the reproductive protein into the genome of the virus (Tyndale-Biscoe, 1994). Such techniques have been used with varying degrees of success on ground squirrels, Spermophilus beecheyi (Nash at al., 2004); feral dogs and cats; wild horses, Equus caballus; and African elephants, Loxodonta africana, amongst other species. Kirkpatrick (2011) indicates that seventy-six captive exotic species and six free-ranging wildlife species are currently managed through the use of PZP immunocontraception. VVIC

15 has been considered appropriate where species are found over large and inaccessible areas. Recombinant-microorganism vectors to deliver reproductive antigens could be spread by sexual transmission, contagion, orally or via an arthropod carrier (Tyndale-Biscoe, 1994). Fertility control by means of vaccination is now a reality.

In Australia, in spite of intensive eradication efforts, the possum is still considered one of the biggest menaces to local crops. Populations of possums kept low using 1080 baits recover through recolonisation and enhanced breeding, making further management very expensive. Furthermore, possums develop poison-shyness—that is they learn to avoid poisoned baits. Scientists have been able to genetically engineer carrots, a food of choice for possums, to express the zona pellucida protein. When injected, the protein can reduce fertility in possums by up to 75% (Weihong Ji, 2009).

Courchamp and Cornell (2000) propose the use of immunocontraception as an alternative to anticoagulants, feline panleukopenia virus, hunting, trapping, and shooting to control feral cats.

In their mathematical simulation, they analyse VVIC. Miller et al.

(2004) report that the GnRH vaccine has had promising results in male cats. More recently, Levy (2011) published her study on the long-term fertility in female cats, which indicates that GnRH immunocontraception works in domestic cats.

Most rodents are r-selected species: they have an early sexual maturity onset, produce many litters over a year’s time, have a short gestation period, disperse well their young, and have a short life expectancy. House mice, Mus domesticus, have a life expectancy in the field of four to six months; females can produce a litter every twenty-one days, and a pair of mice could give birth to hundreds of offspring during their lifetime. These species are best controlled by curbing their reproductive potential rather than by increasing mortality, which is what poison control does. In 1997, Miller et al. compared the efficacy of two immunocontraceptive vaccines on Norway rats, Rattus norvegicus, the mouse zona pellucida peptide (MZPP) and GnRH. They found that GnRH induced 100% infertility in both males and females and could be used as a control agent for rats in the wild.

Avian contraceptives are also being researched. Diazacon is a cholesterol mimic, first developed to reduce cholesterol levels in humans. It inhibits the conversion of desmosterol to cholesterol, thus indirectly blocking the formation of hormones depending on cholesterol and necessary for sperm and egg production. It can be delivered in baits and has been tested on a number of different species (Yoder et al. 2005). Nicarbazin is commonly used on broiler chickens to prevent coccidiosis. Because it disrupts the yolk membrane preventing the formation of the embryo and can be delivered in baits, it has been used to control fertility in different avian species (pigeons, waterfowl).

INSERT An interview with Jay Kirkpatrick Jay Kirkpatrick is the director of the Science and Conservation Center, in Montana, United States. The center, created in 1998, is an independent non-profit organization dedicated to the humane control of wildlife by means of fertility control. Probably the best world expert on immunocontraception, Jay Kirkpatrick has carried out contraceptive research for over 40 years, developing non-lethal and humane methods of controlling wildlife populations, and on non-capture methods for studying reproduction in free-ranging wildlife species.

Q: How did you first start working on immunocontraception?

JK: In 1971, Congress passed the Wild Free-Roaming Horses and Burros Act, granting total and complete protection for feral horses. At that time, herd numbers were controlled by culling –

the horses were rounded up and sent to slaughter, there were no patrol systems, nothing - but this crude system caused and explosion in the population. The Bureau of Land Management and U.S. Forest Service were charged with managing the number of wild horses on public land. I was just starting my carrier then, and the Bureau of Land Management contacted us asking for help in sterilizing wild horses.

Since then, we at the Science and Conservation Center in Montana have been working successfully with 5 different groups of animals: horses, and equids in general. Urban deer, where hunting is not legal or safe; zoo animals in places as far as Australia and Tel Aviv, Israel. We have worked with 85 different species kept in zoos. We have been working with African elephants in 14 or 15 different parks in Africa. More recently, with bison, on Santa Cathalina island. We’ve also embarked on smaller projects, such as wapiti, water buffalo. Immunocontraception has been tried with success not only on ungulates, and hoofed animals, but also on elephants, pinnipeds, bears and even bats.

Q: You have been working in the field of immunocontraception for around 40 years, what are the biggest obstacles you’ve encountered when “bringing” the technique onto the field – technical problems in applying the vaccine, unexpected undesirable consequences, opposition by hunter lobbies, or something other?

JK: There are many problems, a few are scientific, but the real obstacles that stand in the way of widespread application of immunocontraception are social, political, cultural, and economic issues. And biological issues. GnRH analogues are probably going to be the answer for cats and dogs, but when it comes to highly social animals like horses, you can’t interfere with behaviour. You can’t interfere with the complexity of wild horse behaviour, or that of elephants.

Q: Can you briefly summarize the benefits and/or differences of PZP contraceptives versus GnRH contraceptives?

JK: PZP contraceptives have been shown to be safe, and have many advantages over GnRH analogues: they are tissue specific, and lack cross-reactivity with other tissues and protein hormones. They block fertilization, but do not disrupt natural behaviour, such as herd cohesion and social interactions. When used on a pregnant animal, they do not cause abortion, as would GnRH contraceptives in some species. What is more, treated mares are in better physical condition, because they are being spared the costs of pregnancy and lactation. Receptors for GnRH have been found all over the body, the heart, in the cerebellum, in the spinal fluid. Whether or not this has a clinical significance in wildlife it is not fully understood yet. Lupron is a drug used to treat prostate cancer in men. Like other GnRH agonists it lowers male hormones, and slows the growth of prostate cancer or shrinks tumours. Treated individuals were shown to have significant higher risk of cardiac failure.

However, if you want to extinguish certain behaviours, as you might wish to do with pet animals, certain tools like GnRH vaccines and analogues will be better than PZP. Q: I understand that there is a varying degree of reversibility of infertility in different species. Are some species more likely to become permanently infertile?

JK: It depends on the species, as well as the duration of contraception. With horses, we have a larger body of information and we know that you can treat a horse 5 consecutive years and that it will reverse over the years. A horse treated for 3 consecutive years will sometimes reverse in 4 or more years. The mean is 4 years, the range is 1 to 10. In horses treated for 7 consecutive there is no possibility of reversibility.

Each species has a different pattern as far as reversibility goes.

16 Elephants can be treated for several years and will reverse in 18 months.

There are positive effects, too: health gets better, mortality goes down and longevity increases.

Q: What are the short and long term financial costs of immunocontraception application versus traditional culling methods, such as shooting?

JK: If you are a proponent of contraception, you can make the cost look low. You need to consider the cost of training. People need to be trained to deliver vaccines with dart guns, and deal with the animals. We offer three day intensive workshop, and the cost is travel expenses plus 200 dollars.

Then, there’s the cost of delivery equipment. Dart guns range from 900 to several thousand; there are many different delivery systems. It depends on which one you choose.

The real cost is the labour. The cost of vaccines is very low, 24 dollars each. There is no money to be made in wildlife contraception! The cost of labour can be as much as 50.000 dollars a year.

The solution here is to train volunteers, or park employee. The advantage in getting the public involved and in the management of wildlife is that it reduces the conflict. The adversarial relationship between whomever manages the animals and public opinion diminishes.

Q: Is remote delivery of vaccines safe? Are some species more prone to developing granulomas on the site of injection? How is each individual later identified?

JK: First of all, you need to differentiate between an abscess and a granuloma. The first is a swelling which will eventually break open and drain. It is rare and is not life threatening. Granulomas are very common, but they are no more than a hard lump under the skin, and pose no health problem.

In some wildlife reserves there’s someone in charge who checks on the animals every day and recognizes each individual. However, in order to identify animals, you can use a key, just like a plant key. To identify wild horses you can use the differences in colour, facial markings, leg marking (stockings, socks, coronets, 4 different legs, there are over a thousand permutations). There are other ways too. Sometimes you don’t need to identify each individual, but only the social group. With fallow deer you’ve got spots, which are like fingerprints, they are different on each animal. Finally, if you have no other option, you use what we call “saturation bombing”. This means you dart every single fallow deer you see. Of course, some you won’t get the first year, but you do the same next thing next year and over 3 to 5 years you will have achieved your goal.

Q: What percentage of the population needs to be targeted in order to obtain a substantial decrease in fertility?

JK: The answer is site specific. It depends on the fertility rate, mortality rate, sex ratio… If we want to generalize, you want to treat 60 to 75% of the adult females. It depends on the goal you’ve set for yourself, whether you want to decrease the herd, or simply reach zero growth.

Q: Although your field is that of large herbivores, do you see the use of immunocontraception expanding to include smaller animals and carnivores?

JK: Yes, of course. There are teams in Australia working on kangaroos, teams in England working on grey squirrels. Research is being carried out on feral dogs, on different bird species, on all kinds of different animals. Immunocontraception is the answer where traditional lethal controls are not longer legal, wise, safe or publicly acceptable.

6. ITALY

We need another and a wiser and perhaps a more mystical concept of animals. Remote from universal nature and living by complicated artifice, man in civilization surveys the creature through the glass of his knowledge and sees thereby a feather magnified and the whole image in distortion. We patronize them for their incompleteness, for their tragic fate for having taken form so far below ourselves. And therein do we err. For the animal shall not be measured by man. In a world older and more complete than ours, they move finished and complete, gifted with the extension of the senses we have lost or never attained, living by voices we shall never hear. They are not brethren, they are not underlings: they are other nations, caught with ourselves in the net of life and time, fellow prisoners of the splendour and travail of the earth.

Henry Beston, The Outermost House, 1928

In Italy, alien species are estimated at 1,516 (Project DAISIE). Of these, 253 are found in Sicily and 302 in Sardinia. There are 119 of them are in Mediterranean Sea waters, and they are having serious ecological and economical impacts. (HISTOGRAMS) Of the forty amphibian species present in Italy, 40% (eighteen species) are endemic and 7% are established aliens. They all belong to the order Anura: the American bullfrog, Lithobates catesbeinaus, which was first introduced from 1932-1937 and is now widely distributed in the centre and in the north of the peninsula; the Balkan frog, Pelophylax kurtmuelleri, introduced in 1941 and now spreading quickly throughout the north of the country; the marsh frog, Pelophylax ridibundus, and the African clawed frog, Xenopus laevis, the most recently introduced species, present only in Sicily (Lanza et al., 2007). The American bullfrog was intentionally introduced in many countries to be harvested as food and it is now considered a noxious species everywhere. It competes and preys on native amphibian species, has a negative impact on water taxa, and is probably a vector for Batrachochytrium dendrobatidis, a chytrid fungus causing an infection which is decimating amphibian populations worldwide.

In Italy, there are fifty-seven reptile species (Sindaco et al. , 2006); of these, only four are endemic, which constitutes 7% of the total, while 10% are introduced species. The red-eared slider, Trachemys scripta elegans, an established species, is found throughout the territory and resulted from the release of captive individuals. Other alien species present in the country are turtles belonging to the genus Mauremys (M. leprosa, M. caspica, both not established); the Greek tortoise, Testudo graeca; the marginated tortoise, Testudo marginata; the common chameleon, Chamaeleo chamaeleon; Kotschy’s gecko, established; and Agama agama, a species of lizard not established. T. graeca and marginata were introduced by man in historic times and are established alien species, while the common chameleon has reached Sicily and Puglia—where it is occasionally observed—traveling aboard ships. The main threat comes from the red-eared slider, which competes over resources with the endemic European pond turtle, Emys orbicularis, itself an endangered species.

The checklist for birds found in Italy comprises 529 species (Howard & Moore, 3rd edition, corrigenda 8). Of these, sixteen are globally threatened and six have been introduced.

There are fifteen nonindigenous terrestrial mammal species in Italy, four of which were introduced in historic times, and the other eleven having been introduced somewhat more recently.

These species represent a high portion on the seventy-three authocthonous terrestrial species (Spagnesi & Toso, 1999), or 117

17

Aliens by Country (Terrestrial Vertebrates) Species count

18 including species belonging to the Chiroptera, Pinnipeda and Cetacea (Amori et al., 1996).

ITALIAN VERTEBRATE SPECIES Amphibia: Reptilia: Aves: Mammals: Insectivora:

40 species, with 18 endemic and 4 introduced.

57 species, of which 4 are endemic.

529 species.

117 species 16 species with 3 endemic species and 21 subspecies.

29 species, of which only Myotis blythii oxygnaChiroptera: thus is considered endemic.

Lagomorpha: 6 species, with 4 endemic species.

Rodentia: 27 species, comprising 24 endemic subspecies.

Carnivora: 17 species, many of which are endangered because they have been hunted as pests until recently.

Cetacea: 13 species have been observed in Italian waters.

Artiodactyla: 9 species, of which 5 are subendemic.

Nonindigenous mammal species in detail Two subspecies of rabbit, O. cuniculus and O. c. huxleyi, established. Native to the Iberian Peninsula, these rabbits were introduced into Italy in Roman times. Impact: overgrazing activity, especially on islands; it can act as a natural host for the Myxomatosis virus.

Cape hare, Lepus capensis, established. Introduced in Paleolithic times, it is thought it could compete over resources with the Italian hare, Lepus corsicanus.

Eastern cottontail, Sylvilagus floridanus, established. Introduced into Piedmont in the sixties for hunting purposes. Impact: it damages crops, but also orchards because of bark stripping; it is a carrier for Myxomatosis , rabbit haemorrhagic disease virus (RHDV), and dermatophyte fungi, these last transmissible to humans.

American grey squirrel, Sciurus carolinensis, established. Introduced in 1948 to Turin, Piedmont, it is now considered a threat to the native red squirrel, Sciurus vulgaris.

Finlaysonâ&#x20AC;&#x2122;s squirrel, Callosciurus finlaysoni, established. Native of central Thailand. Impact: it damages trees through bark stripping and it competes with passerine species over nesting sites.

Pallas squirrel, Callosciurus erythraeus , not established. Also known as the red-bellied tree squirrel, it comes from Eastern Asia. Widely sold throughout the world, it has been released and become established in different areas, namely Argentina, Japan, and Hong Kong. It is thought it might compete over resources with the endemic red squirrel and damages trees by gnawing bark.

Siberian chipmunk, Tamias sibiricus, established. Native to northern Russia, China, and Japan. Widely sold as a pet, it has escaped repeatedly from captivity and has established populations in many European countries. In Italy, it is found mostly in the north. Impact: it destroys cereal crops and predates on eggs and chicks of Dusky warbler, Phylloscopus fuscatus.

Muskrat, Ondatra zibethicus, of unknown status. Native to North America, it was introduced to Europe in the early twentieth century for fur farming; it escaped into the wild and it is now present in Europe, Asia, and South America. In Italy, it is found only in Friuli-Venezia-Giulia.

House mouse, Mus domesticus, established. It occurs in commensal and noncommensal habitats worldwide. Impact: it predates

on different species of invertebrates, damages crops, and preys on chicks and eggs of seabirds on islands.

Black rat, Rattus rattus, established. It was introduced to Italy in Paleolithic times; archeological findings show that five thousand years ago it was already present in Sardinia (Spagnesi & Toso, 1999). Impact: it preys on seabirds and terrestrial bird species, whether they nest on the ground or on trees on islands; it damages crops and orchards. It acts as a reservoir host of diseases transmissible to humans and domestic animals.

Brown rat, Rattus norvegicus, established. In Italy, it has been observed since the mid-eighteenth century and is now widely spread throughout the territory. Impact: same as the black rat.

Coypu, Myocastor coypus, established. Native to South America, it has been farmed for its fur in different areas of the world. It was imported into Italy in 1928, and since the 1960s it has been intentionally and unintentionally released into the wild. Impact: it can damage crops, aquatic vegetation through feeding, and irrigation structures and bank rivers because of its burrowing habits.

Raccoon dog, Nyctereutes procyonoides, not established. Indigenous to east Asia, it was introduced into the Soviet Union from 1928 to 1958 for fur farming and it has since migrated to most of Europe. Impact: it preys on birds, especially waterfowl.

Raccoon, Procyon lotor, not established. It comes from North America. Impact: it preys on birds and amphibians.

American mink, Mustela vison, established. It was deliberately introduced into Europe to be harvested for fur. It rapidly expanded and in Italy is present in the northeast, but has also been observed in the centre (Spagnesi & Toso, 1999). Impact: it could hybridise with the native European mink, Mustela lutreola , and compete over resources with both the mink and the European otter, Lutra lutra.

Common genet, Genetta genetta, not established. It is found in many European countries. Impact: it acts as a vector for zoonosis and damages crops.

Fallow deer, Dama dama. According to Massetti (1996) it is not possible to determine whether the Italian populations of fallow deer are to be considered an allochthonous species. It was widely introduced for game hunting in historic times throughout Europe. Certainly, the fallow deer was present in Castelporziano in the eleventh century and in San Rossore in the fourteenth century. Impact: it competes with the European roe deer, Capreolus capreolus, and with the red deer, Cervus elaphus, and acts as a reservoir host for infectious diseases of farm animals.

Mouflon, Ovis aries musimon, established. Indigenous to west Asia, it was probably introduced in Sardinia and Corsica in Neolithic times. It is thought that it represents a threat for the alpine chamois, Rupicapra rupicapra, and the Apennine chamois, R. pyrenaica ornata.

Barbary sheep, Ammotragus lervia. Not established. Indigenous to Saharan and arid Africa (Algeria, Chad, Libya, Mali, Niger, Sudan), it is listed as vulnerable. It has been introduced into Spain, the United States, Mexico, and Italy. The population present in Varese, Italy, resulted from an accidental escape from captivity (Gagliardi et al., 2008).

Eurasian wild boar, Sus s. scrofa, established. It is one of the most widely distributed mammals in the world. It occurs from Western Europe and the Mediterranean basin to eastern Asia as far as Japan. It has been introduced into Australia, New Zealand, North and South America, and reintroduced in England. It is bigger and stronger than the indigenous subspecies Sus scrofa majori, indi-

19 genous to the peninsula, and Sus scrofa meridionalis, which has a different origin and is descended from ancient feral and recent domesticated pigs (Oliver W.L.R, 1995). The introduction of the Eurasian wild boar into Italy in the 1950s resulted in the almost complete disappearance of the local subspecies.

Nonindigenous bird species in detail Pink-backed pelican, Pelecanus rufescens, not established. Native to tropical Africa and southern Arabia, it moves by natural dispersion. It has been sporadically observed in various regions in Italy.

Western-reef heron, Egretta gularis, not established. It occurs naturally along the coasts of western Africa, the Red Sea, and as far as India. It has reached Italy by natural dispersion, where it has been observed since the 1970s. It is now included in the Italian bird checklist. It could hybridise with the local egret, Egretta garzetta, resulting in a loss of genetic diversity.

African sacred ibis, Threskiornis aethiopicus, established. It occurs in sub-Sahara Africa and Egypt. In Italy it is present because of accidental releases from zoological gardens. In recent years it has started breeding within heron nesting sites.

Chilean flamingo, Phoenicopterus chilensis, not established. Its natural range goes from Peru as far as southern Brazil. It has sporadically been observed in Italy.

Mute swan, Cygnus olor, established. Native to the northern Palearctic region, it was intentionally released in Switzerland before 1950 and has expanded to Italy, where it reproduces.

Wintering subjects are migratory birds coming from Eastern and central Europe. Impact: damages aquatic vegetation, especially the Potamogeton species.

Black swan, Cygnus atratus, established. Native to Australia and Tasmania. It has been observed in various Italian regions.

Bar-headed goose, Anser indicus, not established. A migratory species often kept in captivity, it has been observed in North America and in Europe.

Canada goose, Branta canadensis, not established. The Canada goose is a migratory species, native to arctic and temperate regions of North America; it comprises about ten to twelve subspecies, of which it is the nominal to have been introduced into Europe. In Italy, it has been observed mostly in the centre and in the north. Impact: it damages crops and has been implicated in deadly aviation strikes.

Egyptian goose, Alopochen aegyptiacus, not established. Native to sub-Saharan Africa and the Nile Valley, the Egyptian goose was introduced into various European countries and has been observed in Italy.

Mandarin duck, Aix galericulata, not established. It comes from East Asia but has been introduced into North America and Europe. Although it is not naturalised, it has been included on the Italian bird checklist.

Ruddy duck, Oxyura jamaicensis, not established. It comes from North America and the Andes Mountains. It has been involuntarily introduced into Europe as a result of accidental escapes from individuals kept in captivity. In Italy, it has been observed since the 1980s. Impact: it hybridises with the local white-headed duck, O. leucocephala, a threatened species.

Bobwhite quail, or Northern bobwhite, Calliplepla virginianus, established. Native to North America, Mexico, and the Caribbean, it was introduced into India, New Zealand, Great Britain, France, and Germany. In Italy it is naturalised in Piedmont and in Lombardy, but it is present in other areas (Mozia Island, Sicily).

Chukar partridge, Alectoris chukar, established. A Eurasian species, it was introduced into many countries for hunting. In Italy it was released into the wild in the nineteenth century but did not survive, and new releases took place in the 1950s. Impact: it can hybridise with the red-legged partridge, Alectoris rufa; and the rock partridge, Alectoris graeca; creating a loss of diversity.

Barbary partridge, Alectoris barbara, established. Native to North Africa, it was introduced without success into many European countries, New Zealand, Australia, and the US. In Italy, it is present in Sardinia, but it is not known whether the Sardinian and the African partridges are separate species.

Erkelâ&#x20AC;&#x2122;s francolin, Francolinus erckelii (Pternis erckelii), established. An alpine species native to East Africa (Eritrea, Ethiopia, Sudan), it was released into various Italian regions around 1950.

Japanese quail, Coturnix japonica, established. Native to East Asia, it was introduced into Hawaii, North America, and various European countries. After 1950 in Italy, it became the species most frequently released into the wild. Impact: it hybridises with the common quail, Coturnix coturnix.

Common pheasant, Phasianus colchicus, established. An Asian species widely introduced worldwide for hunting purposes. In Italy, it has been repeatedly introduced, and was released in the highest numbers in the 1920s and 1940s.

Green pheasant, Phasianus versicolor, not established. Native to the Japanese archipelago, it was introduced into North America, Europe, and the Hawaiian Islands.

African collared dove, Streptopelia roseogrisea, established. It occurs worldwide; in Italy, it is often raised in semi-freedom.

Rose-ringed parakeet, Psittacula krameri, established. It comes from tropical Africa but is found throughout Western Palearctic, the result of intentional and accidental releases. It is present in Italy and reproduces mostly in the centre and in the north. Impact: it competes over nesting sites with local bird species and can damage crops.

Monk parakeet, Myiopsitta monachus, established. It comes from South America and has been introduced into the western Palearctic, United States, the Caribbean, and Brazil. In Europe, it has been released intentionally and unintentionally and has formed groups in different cities. Impact: it competes over food resources with local bird species and may damage crops.

Blue-fronted Amazon, Amazona aestiva, established. Native to South America. In Italy, it has been repeatedly observed; it is ascertained that in Genoa a pair of blue-fronted Amazons has reproduced.

Red-billed Leiothrix, Leiothrix lutea , established. A Sino-Himalayan species, it has been widely traded. Regularly observed in Italy. Impact: it can damage crops and orchards.

Ashy-throated parrotbill, Paradoxornis alphonsianus, established.

Native to southwest China and northern Vietnam, its presence in Italy is attributed to accidental escapes from captivity. Impact: it can compete over food resources with local bird species.

Vinous-throated parrotbill, Paradoxornis webbianus, established.

Same as the vinous-throated parrotbill.

Black-rumped waxbill, Estrilda troglodytes, not established. Native to South Africa, its presence in Italy is due to accidental escapes from captivity.

Common waxbill, Estrilda astrild, not established. Native to subSaharan Africa, the species has become naturalised in many European areas.

20 Red munia, Amandava amandava, established. An Asian species that has been traded for a long time, the red munia is naturalised in many areas in the world. In Italy, it reproduces in various regions.

Common myna, Acridotheres tristis, not established. Native to Asia, the common myna has been introduced to control insects damaging crops in many areas of the world. Highly adaptable, it reproduced beyond expectation and has become naturalised. Its presence in Italy is due to individuals that escaped from captivity. Impact: it can compete with local bird species and damage crops.

Yellow-crowned bishop, Euplectes afer, not established. Native to the area south of the Sahara, it is widely traded and its presence in Italy is due to accidental releases.

Zanzibar red bishop, Euplectes nigroventris, not established. It comes from East Africa, it is widely traded and subject to accidental releases.

Southern red bishop, Euplectes orix, not established. Native to Africa in regions south of the equator, it is widely traded and subject to accidental releases.

Red-billed fire-finch, Lagonosticta senegala, not established. Native to sub-Saharan Africa, it is widely traded and subject to accidental releases.

Red-crested cardinal, Paroaria coronata, not established. It comes from eastern South America, is widely traded, and was accidentally released.

Village weaver, Ploceus cucullatus, established. Found in sub-Saharan Africa, it is widely traded and subject to accidental releases.

Eastern golden weaver, Ploceus subaureus , not established.

Found in southern Africa, it is widely traded and subject to accidental releases.

Red-whiskered bulbul, Pycnonotus jocosus, not established. Native to South Asia, it is widely traded and subject to accidental releases.

Rats Rats, Rattus norvegicus, R. rattus, and R. exulans, have expanded by natural dispersion or have accompanied humans in the colonisation of islands worldwide. The black rat, R. rattus, for examples, spread out of Asia by swimming. These rodents are now present on more than 80% of the world’s major islands, where they can have negative impacts on the flora and the fauna, especially on seabirds. Seabirds, having always reproduced on islands where predators were not present, have not evolved a defence mechanism and are a vulnerable prey.

Rats are found on most Mediterranean islands and are routinely controlled by poison baits containing the anticoagulant brodifacoum. The project of eradication of the black rat, on the island of Montecristo, Italy, used dispersal of poisoned pellets scattered almost exclusively by helicopter. Rats represent a threat to the yelkouan or Mediterranean shearwater, Puffinus yelkouan, by preying on their eggs and chicks.

The risks to predators and other animals from the use of brodifacoum are well known, and they appear to be greatest with aerial baiting techniques (Eason & Spurr, 1995). The capacity of these anticoagulants to persist for months in tissues and organs such as the kidney or the liver heightens the risk of their causing primary and secondary poisoning in many nontarget species. The number of worldwide reports of wildlife poisoned by anticoagulants is growing; mammalian carnivores and predatory and sca-

venging birds are certainly at risk, but herbivores have been shown to have died after secondary exposure to brodifacoum (Stone et al., 1999).

In the United States alone between 1981 and 2004, 244 poisoning incidents of birds and nontarget mammals associated with brodifacoum exposure were reported (US EPA, 2004). In fact, bioaccumulation of brodifacoum—insoluble in water and broken down slowly by microbial activity in baits (Dowding et al., 1999; Eason et al., 1999)—its persistence in carcasses and sub-lethally poisoned animals, as well as the way in which it causes the death of the animal are raising concerns everywhere in the world (Mason and Littin, 2003; Paparella, 2006; Meerburg et al., 2008). It is predicted that on Montecristo the population of the barn owl, Tyto alba, will be wiped out by the use of the poison. Because snails, slugs, and carrion insects (cockroaches, ants) feed on brodifacoum baits or the carcasses of poisoned rodents, they can in turn poison insectivore species, mostly birds, which prey upon them (Webster, 2009). Many different species of migratory birds stop on the island during migration, and some species, such as the Dartford warbler, Sylvia undata, and the spotted flycatcher, Muscicapa striata, reproduce on it. Other animals at risk will be goats, Capra aegragus, rodents other than rats, rabbits, ravens, Corvus corax, bats (Rhinolophus euryale, P.ipistrellus nathusii), and possibly reptile and amphibian species. The rat eradication programme carried out using aerial baiting on Rat Island, in the Aleutians, successfully rid the island of rats but also killed fortythree bald eagles, Haliaeetus leucocephalus, 213 glaucous-winged gulls, Larus glaucescens, and birds of different species (Woods et al., 2009). Given that islands tend to be reinvaded by rats, the long-term use of poison appears to be more detrimental than beneficial. The cost in terms of nontarget animals, bioaccumulation of the substance, as well as the financial costs of repeated operations would be better channeled into new research on fertility control methods to provide a long-lasting solution, with a lesser impact on the environment.

Squirrel wars On May 25, 2012, the Italian newspaper La Stampa published an article, one of many, on the same recurrent theme: “Squirrel wars: Italy vows to eliminate its American invaders.” Italy is “waging a war” against “these strong American invaders” that steal food, space, and resources from the smaller endemic red squirrels, threatening their survival.

The American grey squirrel, Sciurus carolinensis, has been introduced repeatedly in Italy: in Stupinigi, Piedmont, in 1948; inside a park in Genoa Nervi in 1966; in Trecate, Novara, in 1994. Milana & Rocchi (2010) indicate that the squirrels have formed four different nuclei: in Turin and Cuneo, Piedmont; at Genoa Nervi, where they can be found in the urban parks of Nervi and Bogliasco; in Novara; and in Perugia, Umbria. The squirrels have been sighted in Tuscany, too. They have an economic impact because they strip barks, damaging timber crops, and they tend to displace the endemic red squirrel, S. vulgaris. The American grey squirrel, which in autumn exhibits higher body weight compared to the red squirrel, is stronger; moreover, it retrieves seeds stored by red squirrels, depriving them of their stored reserves of food for the winter. Another possible threat comes from the hypothesis that the grey squirrel acts as a reservoir host of parapoxvirus, lethal for the endemic squirrel. Furthermore, the grey squirrel could expand and spread to other countries in Europe. The native red squirrel, considered threatened in Europe, occurs throughout the Italian peninsula with its three subspecies. Its decline is attributed first to the fragmentation of woodland habitats (Celada et al., 1994; Wauters, 1997), and second to the presence of the American grey squirrel. Therefore, designating more green areas to this species should be the first protective measure to be implemented.

21

Various eradication techniques have been used to eliminate the grey squirrel: anticoagulants such as Warfarin, nest destruction, trapping, euthanasia induced by prolonged use of anaesthetics, and surgical sterilisation. Chemical sterilisation is currently being researched. If it is not possible to completely eradicate the grey squirrel by killing more and more individuals, which might simply result in better breeding performance, why not finance research on new, more humane ways of controlling its population? Why not spend and support projects to expand and restore the fragmented habitat of the red squirrel? Finally, only a complete ban on trade could avoid the intentional and unintentional release of exotic species in the environment. In January 2013, the Italian government approves a ban on trade and possession of three different squirrel species, introduced in 2012 in the Annex B of the Council Regulation No. 338/97, regulating the introduction of species dangerous to native flora or fauna. The ban, which is valid in the whole European Union, forbids the import of live specimens of grey squirrels, fox squirrels, Sciurus niger, and Pallas squirrels, Callosciurus erythraeus. Although the ban covers grey squirrels-without clear indications as to what is the fate of the individuals kept as pets or on the market-, the other two species are not the next most problematic ones and the market has already responded by finding new, commerciable species.

Other species of alien squirrels, the Siberian chipmunk, Tamias sibiricus, Finlayson’s squirrel, Callosciurus finlaysoni, and Pallas squirrel, Callosciurus erythraeus, are present within the Italian territory. Free-ranging populations of Siberian chipmunks are found in the north of Italy: in the towns of Verona and Belluno, in the north, where they were introduced in the 1970s, and in the Roman park of Villa Ada, where they were released in the 1980s. Finlayson’s squirrel was first introduced into Acqui Terme, Piedmont in 1981, and into Maratea, Basilicata, a few years later.

Both species cause extensive damage to the vegetation. Chipmunks destroy cereal crops and predate on eggs and chicks of Phylloscopus fuscatus, while Finlayson’s squirrels damage fruit crops, piping systems, and electric cables. Pallas squirrels are present near Varese and it is thought they might compete over resources with the endemic red squirrel.

Coypu The coypu is a semiaquatic rodent that feeds on crops and aquatic vegetation, damaging both. Coypus can alter aquatic ecosystems and weaken irrigation structures, or river banks, through their burrowing habits. Due to dispersal habits and the high reproductive rate of the species, complete eradication is impossible.

INSERT Interview with Samuele Venturini Biologist Samuele Venturini has worked for years with coypus and is now responsible for a neutering project.

Coypus are a non-problem, Venturini tells us. Of course, within a certain context, any animal can become problematic, depending on various factors, such as population density. While a small number of coypus doesn’t seem to cause any damage, high density populations could be a problem for agriculture.

We are working on a neutering project in Buccinasco, near Milan, using an ecological method to contain the population. Our aim is to solve the problem a given species may represent. In the United States, studies carried out on coyotes proved that fertility control works and that treated populations of coyotes exhibit a lower rate of predation on sheep.

22 Culling can have a counterproductive effect on the population trend. In Italy, coypus have been culled for twenty years, yet their numbers increase constantly. Studies showed that culling programmes can increase reproduction capacity. Females get pregnant more often and have more offspring, because they tend to hide and move about less than males. The more active adult males are killed in greater numbers, favouring younger males which, like females, don’t move about very much. When an animal gets killed, a niche is made available and it gets filled right away, in this case by younger animals with higher reproduction rates. Hunting pressure also selects for the early onset of sexual maturity. In the wild, coypus start reproducing at 6 to 8 months of age. Fur farming selected animals which could reproduce earlier, at 3-4 months of age, favouring individuals reaching sexual maturity earlier.

We neuter coypus by surgical intervention. Males and females are live-trapped and taken to a veterinary clinic, where they undergo a minor surgical procedure and some blood tests. Neutered animals are then marked in order to be later recognized. After this procedure, the animals are returned to the same place where they were caught. Coypus are highly territorial and when an individual occupies a niche, it means other coypus will stay away and won’t have access to trophic resources and nesting sites, and therefore won’t be able to reproduce. Over time, the population tends to reach a balance. New arrivals are chased away, and when resources are lacking females can abort or terminate pregnancies through resorption, so that the number of individuals diminishes. In the wild, coypus live 4 to 7 years; in captivity – in parks or natural reserves – they can reach 20 years of age.

As I said, the final objective of the project is to reduce population density. Farmers want that the number of animals be kept under control.

At the moment, we’re still in an experimental phase of the project and we need more time to assess the various aspects and results of this technique. Once the animals are neutered and returned to their sites, a long period of observation starts. This is the hardest part, requiring manpower and long hours of work.

Coypu sterilization can be used only in circumscribed and easily monitored areas, such as parks and karst springs. In the open countryside, it is impossible to contain the expansion of the animals through this method alone. However, sterilizing a small, circumscribed population limits the expansion of the species, allowing for better control.

A common problem in the countryside is the stability of river banks: it is feared that coypus make them fragile and friable by digging burrows. Coypus prefer to dig their dens where embankments have a certain slope and there is no vegetation. They don’t always excavate burrows; in the wild, they build a den inside small rafts made of dry vegetation. Where this is not possible but there are trees and bushes, coypus settle for a good hiding place.

They only dig burrows when there is no vegetation. Tunnels measure between 50 cm and 2.30 metres in length, and rarely reach 5 m. These tunnels don’t make embankments unstable, but lack of vegetation-the result of anthropomorphic disturbance-does.

Tunnels excavated by coypus can have a positive impact on the ecosystem, offering shelter to other animals, such as wintering amphibians or water rails. Often, coypus use abandoned burrows, excavated by otters, once more common throughout Italy, or by other coypus. When tunnels are artificially refilled, coypus will dig more burrows and thus make banks more unstable; once again, this problem is exacerbated by human intervention. Coypus are highly social animals and sometimes share their dens.

During hunting and culling campaigns, they sometimes react by digging deeper and larger tunnels, up to 5 m. in depth, to house more individuals.

To solve the problem of so called “pest” species you need to acquire an in-depth knowledge of the biology of the target species

and its habitat. Many people talk about England as the country where coypus have been eradicated completely, but it was not a simple process. First of all, in England they tackled the problem very early on, before the population could expand. Besides, in the English countryside there are no capillary systems for irrigation, but only small rivers and drainage basins. There weren’t many animals, and they were isolated. Limited but well aimed funding was sufficient to capture most of the animals. And, a few very cold consecutive winters decimated the population, making possible a complete eradication where it could not have been so.

It is possible to contain the damage done to banks using embankment barriers. In Mantua and in Rovigo, they used special nettings which prevent coypus from digging, strengthen embankments and favour the process of recolonization by marsh vegetation. Natural embankment vegetation gives extra stabilization, creates a favourable micro-environment, filters the water and attracts insects and birds. These, in turn, protect crops by feeding on certain noxious insects. Farming is made more secure, because embankments are less fragile and do not collapse when farmers drive over them with a tractor. In Argentina - the coypu’s original range – they use and simple and functional method to contain the population. Unlike us, who sow crops up to the water’s edge, they leave a strip of a few metres of unsown land between the field and the water, to allow for vegetation growth.

In Italy, the structure of the soil is alluvial, and therefore more friable. Five to 10 metres of unsown land would be sufficient for vegetation to colonize the embankments. Natural vegetation keeps coypus from damaging crops: in the wild, they prefer feeding on the aquatic vegetation they find on the river banks rather than corn or other crops. Besides, they don’t like straying from the water because by doing so they expose themselves to predators. Coypus damage crops only when they are deprived of their natural habitats.

Wild boars Located in coastal central Italy, the Maremma Regional Park covers an area of about 10,000 ha. Wild boars are some of the animals inhabiting the park. They are opportunistic feeders so while plants make up most of their diet, they also feed on vertebrates and invertebrates, carrion, eggs, fruits and fungi. When food is scarce, they can seriously damage agricultural crops of any kind.

Because they can reproduce at rates higher than most large mammals, resulting in high local densities, they have a strong negative impact on human economy. Although traditionally hunting has been used to control wild boars populations, the Maremma Regional Park is now looking into new technologies to manage wildlife, namely fertility control. Andrea Sforzi, biologist, will work with Giovanna Massei, an Italian wildlife ecologist working at the Food and Environment Research Agency in York, England. For over 25 years, Massei has been working on nonlethal approaches to mitigate human-wildlife conflict. The park will test a boar-operated-systems (BOS), a device used to deliver bait-delivered pharmaceuticals to wild boars and pigs. BOS is a metal pole onto which is fitted a cone, which boars can open and feed from. The study aims to test whether free living wild boars will feed from BOS devices. If so, in the second phase of the project, they will be fed baits treated with oral vaccines (Massei et al., 2008; Massei et al., 2011). At present, GnRH oral vaccines are still being perfected and have to be approved for use by the Italian Health Authorities.

Cervids The fallow deer, Dama dama, was introduced into Italy in the Neolithic. Since then, it became extinct and was reintroduced sev-

23 eral times. Although it can hardly be considered an alien species, it often behaves like an invasive one and can compete fiercely with local ones, such as the endemic red deer, Cervus elaphus, in the Mesola Park, or the roe deer, Capreolus capreolus , at the Maremma Regional Park.

The Mesola Forest, situated near Ferrara in the north of Italy, covers an area of 1,058 ha. The population of fallow deer became extinct in 1945 and was reintroduced in the Fifties and Sixties. It expanded rapidly and in recent years has seriously reduced pastures by overgrazing. The presence and rapid expansion of the fallow deer represents a threat for the small population of about 120 individuals of red deer. Attempts to control the fallow deer through by hunting started in 1982, but they only exacerbated the problem. 3,180 animals were shot dead, and numbers keep rising, with the population rising from 602 individuals in 2006 to 950-1,000 in 2011. Modena Local Veterinary Service (AUSL) proposes a project based on immunocontraception (Ferri et al., 2011). For a period of 7-15 years female deer are treated with GonaConTM vaccine and ear-tagged with the objective to reduce deer population to a small group considered of “historical importance”, comprising about 20 to 40 individuals. To the present time, the Italian Health Authorities have not yet approved the use of the vaccine, much to the detriment of the whole Mesola ecosystem. We badly need alternative solutions to culling through hunting, which is both undesirable and opposed by the general public.

Birds Since 1997, the Modena Local Veterinary Service (AUSL) has been working on fertility control of feral pigeons using an oral veterinary licensed drug, Ovistop®, ACME (Ferri et al., 2009). The use of the vaccine has been integrated with architectural barriers to limit pigeon access to scaffold holes, used for nesting, while still allowing other species (birds, mammals, reptiles) to access them. The project resulted in the decrease of urban pigeons and the preservation of other species, such as common swifts, Apus apus, insectivore passerines, bats and geckos. While pigeons are not an alien species, they certainly are an invasive one, and the success of this effort could be applied to other situations.

The active component in Ovistop is Nicarbazin, a compound which decreases egg production and hatching rates by disrupting the yolk membrane. It is non toxic, has anticoccidial properties and is considered ethical; plus, it has already been used on Canada geese, Branta canadiensis, and other waterfowl to control fertility.

7. SOCIAL AND FINANCIAL IMPLICATIONS

“An ounce of prevention is worth a pound of cure.”

Henry de Bracton, 1240, jurist

Biological invasions are mostly the intentional or unintentional result of economic activity. We have seen how certain ecosystem, such as islands, lakes, rivers, and near-shore marine systems, or systems of low diversity with few predators, are more vulnerable to colonisation by alien species. But a country’s socioeconomic factors and land use increase the introduction and spread of allochthonous species due to the increase in trade, transport, and human movement. Transport systems support high trade volumes, both national and international. Economically developed countries possess good transport systems and their road networks cover large areas, especially in densely populated regions.

Roads act as introduction pathways, people act as vectors, and disturbed land – degraded habitats favour biological invasions (Marvier et al., 2004) - surrounding roads, maintenance works, and movement further promote the process of invasion. Finally, also the volume of disturbed and suburban areas, which also favours the spread of invasive species, is high in developed countries (Sharma et al., 2009).

The control of wildlife and unwanted exotic species is a growing industry. Biologists and other researchers tend to concentrate their studies on projects for which they are more likely to obtain funding. Invasive species which have a proven economic impact are of higher interest than casual, or naturalised species. A study carried out by Pyšek (2008) highlights that the most-researched invasive animals are the ones with a serious impact. Online research using science search engines shows the existence of a large number of studies on zebra mussels, Dreissena polymorpha, rats, the house mouse, possums, coypus, wild boars, and foxes. Eradication programmes of these pest species or papers on the same topics offer an attractive and quick solution to a costly and complex problem. The bias does not affect taxa alone, but also countries: most research on exotic invasive species takes place in Europe and the United States (GRAPH from Pyšek, Geographical and taxonomic biases in invasion ecology). Wealthy countries with a high gross domestic product and large trade volumes have more alien species, which partly justifies a higher concentration of research in this area. At the same time, fundamental aspects of the invasion process—habitat properties, the process of naturalisation, and each new case of biological invasion, amongst others—are understudied and need to be understood to address the problem and to effectively curb new invasions.

In Europe, out of the ten thousand invasive alien species present, an estimated 10%-15% of them are expected to have a negative impact. A study carried out in 2009 estimated that IAS cost Europe about €12 billion per year, but this is expected to keep rising along with the rise in the number of new alien species. On a larger scale, according to Pimentel (2005), alien species cost the global economy $1.4 trillion per year, 5% of global production.

However, the question of allochthonous species is open to economic solutions (Perrings at al., 2002). The regulatory framework of a country—e.g., quarantine, the list of exotic species which can be traded—could play an important role in limiting further introductions or the spread of existing alien species.

In a globally expanding economy where lobbies are likely to fight against stricter regulations aimed at limiting trade of exotic species, trading partners should be encouraged to include specific insurances covering the costs of the damage these species could cause. These insurances would prevent higher ecological and economical costs resulting from the damage inflicted by invasive species. Taxes on exotics could push stakeholders with a specific interest in trading wildlife (sellers and buyers of exotic species, organisations related to hunting and fishing, farmers raising new species) into learning more about the species they trade and their potential as invasives. All traders in exotic species should know that the longer a species has been marketed, the greater the probability that it could escape and get established (Enserink, 1999). Both traders, and buyers alike, should pay taxes.

Intentional release of exotic species should be discouraged by hefty fines. Money coming from these taxes could be spent on prevention, control, and research.

In Europe, the import of allochthonous species is covered by the Wildlife Trade Regulation. Although the WTR could suspend the import of potentially harmful species, its current rules only cover four species but does not regulate trade and holding within the European Community. The Habitats Directive and the Birds Directive also have a general provision asking Members States to avoid or regulate the introduction of alien species in protected areas.

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