REINTRODUCING THE OSPREY TO PORTUGAL Luís Palma, Pedro Beja, Andreia Dias, João Ferreira and Marco Mirinha CIBIO, Research Center in Biodiversity and Genetic Resources Porto University, Vairão, Portugal , http://cibio.up.pt/
Conference on Eagles of Palearctic: Study and Conservation Yelabuga, Tatarstan Republic, Russian Federation 20-22 September 2013
The Osprey Pandion Haliaetus was a common breeder along the Portuguese coast at the beginning of the 20th Century with a reasonable estimate of at least 22-30 pairs. Decline was due to persecution and human occupation of the coastline, and to large scale changes in forest management (affecting the tree-nesting subpopulation).
1900
1950
The desertion of nest sites began around growing urban areas and first summer holiday settlements, coupled with state rewarded persecution which lasted from 1934 to 1967.
1970
1980
After 1960, decline was due to the onset of mass tourism in the South coast, agricultural and tourism development in the SW coast, and forest management changes in the northernmost former breeding area.
Despite a c.1km wide permanent game reserve created in 1983 all along the rocky coast and a Protected Landscape Area (110 km long , 744 km2) declared in 1988 in the SW coast, and upgraded in 1995 to Natural Park, the species went extinct as a breeder in 2001. In the meanwhile, no specific conservation plan could be set up due to indifference of authorities.
After an first unsuccessful attempt in 1999, after the accidental death of the female of the last breeding pair, a 5-years reintroduction project could finally be set up in 2011. The project is based in hacking techniques and closely follows the experience of similar successful projects previously carried out in England, Spain and Italy.
To re-establish a self-sustaining Osprey breeding population back to its historical breeding range in the Portuguese rocky coast, most of it now declared as Natural Park.
A preliminary suitability assessment of potential release areas considered extent, food availability, breeding conditions, contamination, human pressure, mortality risks, use by migrating and wintering ospreys, and logistic and bureaucratic limitations. A set of 11 potential areas were investigated, including 2 large estuaries, 2 large coastal marshlands, 2 medium marshes, 1 large artificial reservoir and the Southwest rocky coast. The 3 best areas were visited by expert scientists of donor countries and the administration.
The Alqueva dam is the largest artificial reservoir in Europe, with a surface of 250 km 2 and a shoreline of c.1160 km. The dam was chosen as the osprey release site for its large area of foraging and breeding habitat, high prey availability and accessibility, light and easily manageable human pressure and favourable logistic and technical conditions.
Lisbon
Alqueva dam
Hacking site
20 km
The Alqueva reservoir is located in the Guadiana river in SE Portugal near the Spanish border. All project facilities are located on a 4 km long narrow peninsula that projects into the main body of the reservoir within a large closed private estate.
The project facilities include e.g. the field base with basic accommodation, solar panels, fish processing area, 4-wheel drive car, boat, floating fish cage, hacking tower, feeders and artificial perches.
Shadow from tree Shading cover
Facing North
Palm fronds
Folding front panels
Lateral shading panel
Inside pen CCTV image Feeding sleeve
Feeder
Electrical panel
Watching holes
Washable false floor
Water sprinkler system
The tower is an elevated wooden structure near the shore of the reservoir. It is divided in 4 pens and is equipped with a water sprinkling system and closed-circuit television (CCTV) cameras. The tower is connected to the field base by electrical and optical cables. The inside of the pens can be viewed at the field base and video images are recorded for later viewing.
Nestlings are taken from large healthy populations of Sweden and Finland under coordination of Bjรถrn Helander from Sweden (right on the left photo) and Pertti Saurola from Finland (right photo). Number of nestlings is up to 6 each country per year.
Nestlings travel on direct flights, scheduled to arrive at late afternoon at Lisbon’s airport in order to be taken by car to the Alqueva dam during the night. This way heat stress is prevented. Car travel takes about 3 hours and the birds are put into the hacking tower between 24:00 and 01:00 a.m.
The hacking tower is divided into four compartments of 2,20 x 2 x 1,8m. Each has a wooden frame in the middle upon which a nest is built, made of branches and soft natural lining material. Thick logs are provided for perching at older age. The nestlings are divided in groups of 3-4 per compartment according to age and weight.
While nestlings are caged, meals are delivered 3 times/day at a rate of 100-150g/meal/bird of eviscerated and sliced fished. The size of the slices increases with time. After release, whole fish cut in large portions is provided on the feeders twice a day at a rate of 220-230g/meal/bird.
All birds are radiotagged before being released to allow following them throughout the dam. Transmitters are equipped with posting sensors to allow detecting mortality. Three models were tested, the best performing being the Backpack Biotrack TW-3 10-28, 16g, c.10 km range. Tailmounts are to be rejected because they can cause tail feathers to fall down.
At the age of about 9 weeks and after c.3 weeks inside the hacking tower, the front panels are slowly opened just before dawn to release the birds. They are routinely observed from the distance and radiotracked at every feeding time until dispersal, 3 to 7 weeks after release. The birds are weighed on a automatic perch-scale while photographed by a nearby camera trap.
33 nestlings were translocated so far, of which 29 were released. 4 birds died before (accident/disease) and 3 after release (predation). 26 fledglings (79%) dispersed (15 males, 11 females) but 3 males dispersed prematurely (survived?).
Besides a first clinical evaluation in the countries of origin, a second is done at Lisbon’s airport, and blood samples and cloacal swabs taken for screening against avian influenza and Newcastle disease. A third clinical assessment is done during the bird’s stay at the tower and whenever any bird shows signs of illness. Haematology, parasitology, bacteriology and virology analyses are routinely carried out.
Two birds suffered from accidental tendon problems (one slipped and one complete rupture). Two birds showed osteodystrophy with fragile bone tissue, skeletal malformations, and coracoid luxation or multiple fractures. The 4 birds were investigated at a veterinarian hospital and then treated at rehabilitation centres but didn’t survive. Suspected calcium deficit was investigated in 2012 showing high Ca-P imbalance. Calcium and VitD3 supplement was provided and fish nutritional composition will be analysed.
The Alqueva dam lacks suitable tall trees for natural nest building by ospreys. To tackle this, six 1 m-wide metallic nest platforms atop telescopic 10 m poles were erected in islands. Platforms are filled with vegetable material. More nest platforms will be built in the next years. The Alqueva dam has about 200 islands under public management.
Main requirements: 1. official agreements of the donor countries’ authorities on the export of nestlings; 2. CITES certificates (only Finland); 3. veterinarian certificates (reports on the occurrence of diseases in the origin countries and clinical evaluation before travel and upon arrival; and 4. testing against Avian Influenza and Newcastle Disease before release
Awareness meetings with hunting and fishing associations and local authorities, which surround the dam are currently in preparation. A brochure about the species and its history in the country, the project justification, rationale and reintroduction techniques, and conservation issues was produced and will be distributed throughout the release area
Implementation Research Centre on Biodiversity and Genetic Resources / Porto University Partners Finnish Museum of Natural History Finnish Osprey Foundation Swedish Museum of Natural History Swedish Society for Nature Conservation Highland Foundation for Wildlife, Scotland Migres Foundation, Spain SAIP, Sociedade Alentejana de Investimentos e Participações ICNF, Portuguese Nature Conservation and Forests Institute EDIA, Alqueva Development and Infrastructures Company Veterinarian Hospital of Évora University RIAS Rehabilitation Centre
Sponsor EDP, Portuguese Electric Company Supports Häme and Pirkanmaa Centres for Economic Development, Transport and the Environment, Finland Swedish Environment Protection Agency Spanish Ministry of the Environment GREFA Rehabilitation Centre, Spain TAP Air Portugal Lisbon Oceanarium Reguengos de Monsaraz Municipality Sparos, Lda.