Ford2017 by European Wilderness Society

Opportunities and challenges for the study and conservation of large carnivores Adam T. Ford PII: DOI: Reference:

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Please cite this article as: Ford, Adam T., Opportunities and challenges for the study and conservation of large carnivores, (2017), doi:10.1016/j.fooweb.2017.06.001

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ACCEPTED MANUSCRIPT Opportunities and challenges for the study and conservation of large carnivores

Adam T. Ford

Canada Research Chair in Wildlife Restoration Ecology

Assistant Professor Department of Biology

The University of British Columbia - Okanagan Campus

SCI 109, 1177 Research Road, Kelowna, BC, Canada, V1V 1V7

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p: 250 807 9773

ACCEPTED MANUSCRIPT Introduction Few taxa have captured the imaginations of ecologists, or the ire and admiration of the

public, like that of large predators - sharks, tigers (Panthera tigris), bears (Ursus spp.),

and lions (Panthera leo) among others. Images of these species are used to market

products, are featured prominently in childrenâ&#x20AC;&#x2122;s literature, featured as logos for sports teams and other organizations, and serve as a rallying point for conservation action. This

elevated profile brings with it a nearly mythical status that can obfuscate understanding

of the role these organisms play in the ecosystem (Ford et al., 2017; Mech, 2012) Moreover, in mainland Europe (Chapron et al., 2014), North America (Larue et al.,

2012) and Africa (Woodroffe, 2011), many large carnivore populations are recovering.

These recoveries are occurring in human-occupied areas, forcing society to quickly

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identify the knowledge gaps and social perceptions of large carnivores in the face of impending coexistence and conflict (LĂłpez-Bao et al., 2017). This special issue covers a diversity of issues related to the methods, assumptions, and measured impact of large carnivores in terrestrial landscapes. Here, I synthesize these contributions and highlight the key challenges and opportunities in the science of large carnivore ecology and management.

Challenges and opportunities in large carnivore research Large carnivore ecology appears in the foundational texts of conservation (1940s), where Aldo Leopold and others referred to the impact of predator decline on the rise of herbivores and the decline of plants, describing a process that later became known as a

ACCEPTED MANUSCRIPT trophic cascade (Hairston et al., 1960; Layman et al., 2015; Ripple and Beschta, 2005). In spite of this legacy, contemporary large carnivore science faces a number of ongoing

challenges that the authors in this special issue have identified. These challenges are

linked to: (1) the generality of carnivore effects across different ecosystems; (2) the

methods and hypotheses used to test for carnivore effects; (3) obfuscation of conservation and ecology; and (4) a cultural clash of ideologies within and among researchers, the

public, and conservationists.

Generality of carnivore effects

In spite of the long history of large carnivore research in ecology, there remains little

consensus among the research community about where and when the effect of these

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predators exert primacy over other drivers of ecosystem function. Some authors have argued that these effects are general (Terborgh and Estes, 2010), while others have found placed greater emphasis on the ecological contexts that dictate the strength of carnivore effects (Schmitz, 2010). For example, the stochastic nature of rainfall in much of Australia generates highly irregular and irruptive temporal patterns in productivity that can swamp the top-down effects of predators (Cooke and Soriguer, In press; Morgan et al., In press-a; Morgan et al., In press-b).This pattern differs radically from the more regular seasonality observed in temperate systems, like the Greater Yellowstone Ecosystem and Isle Royale. Environmental variation, along with local drivers of food web complexity, can strengthen or weaken the top-down effects of predators (Ford and Goheen, 2015; Haswell et al., In press; Morgan et al., In press-b; Shurin et al., 2002;

ACCEPTED MANUSCRIPT Winnie Jr and Creel, In press). In some respects, the lack of generality of carnivore effects is surprising, given a fairly common architecture of many food webs across

widely-varying taxa (Fleming et al., 2012; Meadows et al., In press; Ritchie et al., 2012).

Indeed, Fleming et al. (In press) describe highly varying effects of Canids, which occur

on every continent and share many life history characteristics.

Further challenges arise when addressing the relative contributions of consumptive

and non-consumptive effects. Winnie Jr and Creel (In press) and Haswell et al. (In press)

describe the ongoing debates about non-consumptive effects of large carnivores on their prey. Saggiomo et al. (In press) reminds us that consumptive and non-consumptive

effects of carnivores on their prey are but two of many interactions found in nature.

Carnivores are also associated with mutualism, commensalism, parasitism, amensalism–

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alongside a diversity of dietary specialization. Together, this diversity of trophic interactions paints a challenging picture of complexity that ecologists have generally failed to consider when assessing ‘the total effect’ of large carnivores (Fleming et al., In press; Saggiomo et al., In press). Moving forward, the extent to which science will meet the challenge of understanding the generality, contexts, and interaction types that give rise to a carnivore’s role in the ecosystem will depend on scientific advancement in the methods and hypotheses used in future studies.

Methods and hypotheses Large carnivores are not easy to study in the wild. They are often rare or cryptic, highly mobile, and physically dangerous to researchers. Relative to smaller fauna, animal care

ACCEPTED MANUSCRIPT protocols or logistics can limit the types of experimentation that can be performed on large carnivores in natural settings (Meadows et al., In press). Removal or addition

experiments (i.e., of large carnivores) are both highly controversial and often driven by

management objectives rather than pure hypothesis testing (Lewis et al., 2016). Because

of these challenges, researchers are often searching for ecological relationships with data that was never designed to test the hypothesis at hand (Allen et al., 2017; Allen et al.,

2014). For example, Cooke and Soriguer (In press) describes the many confounds and

data limitations associated with one of the world’s greatest carnivore exclusion efforts – the ‘dingo fence’ across Australia (see also (Yelland and Fraser, 2012). The fence was

established by 1885 and was designed to increase agricultural (i.e., domestic sheep

operations) productivity by reducing immigration by dingoes (Canis lupus dingo) – and

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therefore, livestock depredation. Several researchers have taken advantage of this management effort to assess the effects of dingoes on the ecosystem. Had ecologists designed this fence for the purpose of conducting research on dingo ecology, it is likely that there would have been much greater care to avoid systematic bias in the treatments (dingo removal vs. control) from land use and climate. Such biases continue to undermine conclusions about causality in Australian food webs (Cooke and Soriguer, In press). Similarly, Winnie Jr and Creel (In press) point out that declining elk populations occurred with wolf reintroduction to the Greater Yellowstone Ecosystem, but both wolf (Canis lupus) and elk (Cervus elaphus) abundance co-vary with climate and the behaviour of sympatric carnivores. Like the dingo-system, this covariation makes it difficult to assign causation in the dynamics of the Greater Yellowstone Ecosystem.

ACCEPTED MANUSCRIPT To counter these challenges posed in Australia, Yellowstone, and other large carnivore systems, Engeman et al. (In Press) advises that more rigorous study designs, as

well as more precise language to describe the outcome of correlative studies, is needed.

Failure to adopt this advice means that, relative to many other subdisciplines in ecology,

research on large carnivores will continue to be hampered by low rigour and obfuscation. The development of new technology and study designs linking field, lab, and

correlative/landscape scale experiments offers some promising avenues to meet this

challenge (Ford and Goheen, 2015).When such techniques are not used, greater effort is needed by authors to improve the accuracy and precision of language that describes the

confidence of results. For instance, Allen et al. (2017) describe issues that undermine

confidence in the literature on large carnivore ecology, lament the degradation of

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communication practices associated with this body of literature, and report that ‘science denial’ is now present in the field of large carnivore research. Addressing these issues will be particularly important if scientists hope to distinguish the conservation and ecological outcomes of large carnivore research.

Obfuscation of conservation and ecology Almost every contribution to this special issue refers to the return of wolves to the Greater Yellowstone Ecosystem as a conservation success story, with many also confirming that such a reintroduction triggered a trophic cascade via suppression of elk and the release of woody plants (Populus spp., Salix spp.). The frequent mention of these two ideas together – conservation of large carnivores and the top-down effects of large

ACCEPTED MANUSCRIPT carnivores – highlights a central challenge in large carnivore research: conservation and ecology can be strange bedfellows. Allen et al. (2017) posits that there are unappreciated

pathways to conserve large carnivores that do not depend on their putative role in trophic

cascades. Indeed, greater efforts are required by conservationists to demonstrate the value

of large carnivores to communities, the general public, land and wildlife managers, and policy makers irrespective of any top-down effects on the ecosystem. Decoupling

carnivore conservation from carnivore ecology will not be easy, but it is important if

science is to aid in management and address basic research problems. The challenge of advancing carnivore conservation without the crutch of trophic cascades will, like most

successful conservation efforts, rely more on social science than the validation of a

particular ecological hypothesis (Lewis et al., 2016; McLeod et al., 2015). The social

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science of carnivore conservation should take the forefront in this regard, focusing both on ‘who’ does carnivore ecology and ‘how’ these results can shape conservation outcomes.

A cultural clash of ideologies Like other aspects of science, large carnivore ecology does not occur in a vacuum devoid of human experience. Researchers and their networks of stakeholders and colleagues, the landscapes in which research is conducted, and the species of focus – all shape the types of ecological questions and methods used by researchers. Conservation research is not conducted in areas or on species proportionate to species richness, need, and endangerment and conservation researchers are not publishing in proportion to the areas

ACCEPTED MANUSCRIPT where conservation work is being conducted (Allen et al., 2017; Clark and May, 2002; Clucas et al., 2008; Fazey et al., 2005; Ford et al., 2017). Moreover, there is a danger in

when researchers become ‘encamped’, sharing ideas with like-minded colleagues, and

not challenging themselves or the data using principles of strong inference and multiple

hypothesis testing (Chamberlin, 1931; Platt, 1964), to the detriment of science. Indeed, (Allen et al., 2017) documents how systematic bias in citations or ‘citation inbreeding’

contributes to an inflated perception of how impactful wolves and dingoes can be in

ecosystems.

The field of large carnivore research, science and conservation included, would be

well served if researchers could better separate the values they have toward wildlife, their

beliefs about how nature functions, and what the data actually show. This is not easy, and

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to overcome this challenge we suggest that reframing study designs with questions like ‘what is the effect of carnivore X on trophic level Y’ to questions like ‘what is driving the abundance and distributions of species X and Y’ (Eisenberg et al., 2013; Peterson et al., 2014). Simply put, all scientists have the opportunity to create a culture in which researchers need not fear that publishing a result showing an absence of a top down effect will diminish the validity of their science, will alienate them from their colleagues, or will hinder the conservation status of their focal species.

Conclusion Ironically, it is perhaps because large carnivores are so deeply engrained in the modern conservation lexicon that it has become so difficult to understand the ecological role of

ACCEPTED MANUSCRIPT these iconic species (Eisenberg et al., 2013; Mech, 2012). These species attract funding for conservation and a profile that few other organisms do, but they can also become the

targets of costly persecution programs (Brook et al., 2015; Hervieux et al., 2014; Proulx

et al., 2015). Calls for enhanced rigour in carnivore ecology, or provision of evidence that

the effects of carnivores are weak or similar to that of other organisms (e.g., plants and herbivores), can be taken as a threat to conservation of these species (Allen et al., 2011;

Ford et al., 2017; Letnic et al., 2011; Ripple et al., 2017). Practitioners of conservation

research are struggling to resolve this dialogue. Further efforts are needed to diversify the species studied, the methods used, the hypotheses tested, the locations of study, and the

identity of scientists conducting this work will further improve our ability to understand

and conserve large carnivores in the future. This special issue marks a critical point of

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departure to re-evaluate how we think of large carnivore research.

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