ABSTRACT
Wildlife must increasingly balance trade-offs between the need to access important foods and the mortality risks associated with human-dominated landscapes. Human disturbance can profoundly influence wildlife behavior, but managers know little about the relationship between disturbance-behavior dynamics and associated consequences for foraging. We address this gap by empirically investigating the consequences of human activity on a keystone predator-prey interaction in a region with limited but varied industrial disturbance. Using stable isotope data from 226 hair samples of grizzly bears (Ursus arctos horribilis) collected from 1995 to 2014 across 22 salmon-bearing watersheds (88,000 km2) in British Columbia, Canada, we examined how human activity influenced their consumption of spawning salmon (Oncorhynchus spp.), a fitness-related food. Accounting for the abundance of salmon and other foods, salmon consumption strongly decreased (up to 59% for females) with increasing human disturbance (as measured by the human footprint index) in riparian zones of salmon-bearing rivers. Declines in salmon consumption occurred with disturbance even in watersheds with low footprints. In a region currently among the least influenced by industrial activity, intensification of disturbance in river valleys is predicted to increasingly decouple bears from salmon, possibly driving associated reductions in population productivity and provisioning of salmon nutrients to terrestrial ecosystems. Accordingly, we draw on our results to make landscape-scale and access-related management recommendations beyond current streamside protection buffers. This work illustrates the interaction between habitat modification and food security for wildlife, highlighting the potential for unacknowledged interactions and cumulative effects in increasingly modified landscapes.
ABSTRACT
Although humans have long been predators with enduring nutritive and cultural relationships with their prey, seldom have conservation ecologists considered the divergent predatory behavior of contemporary, industrialized humans. Recognizing that the number, strength and diversity of predator-prey relationships can profoundly influence biodiversity, here we analyze humanity's modern day predatory interactions with vertebrates and estimate their ecological consequences. Analysing IUCN 'use and trade' data for ~47,000 species, we show that fishers, hunters and other animal collectors prey on more than a third (~15,000 species) of Earth's vertebrates. Assessed over equivalent ranges, humans exploit up to 300 times more species than comparable non-human predators. Exploitation for the pet trade, medicine, and other uses now affects almost as many species as those targeted for food consumption, and almost 40% of exploited species are threatened by human use. Trait space analyses show that birds and mammals threatened by exploitation occupy a disproportionally large and unique region of ecological trait space, now at risk of loss. These patterns suggest far more species are subject to human-imposed ecological (e.g., landscapes of fear) and evolutionary (e.g., harvest selection) processes than previously considered. Moreover, continued overexploitation will likely bear profound consequences for biodiversity and ecosystem function.
Subject(s)
Ecosystem , Ursidae , Animals , Predatory Behavior , Biodiversity , Biological Evolution , EcologyABSTRACT
The concept of ecotypes is complex, partly because of its interdisciplinary nature, but the idea is intrinsically valuable for evolutionary biology and applied conservation. The complex nature of ecotypes has spurred some confusion and inconsistencies in the literature, thereby limiting broader theoretical development and practical application. We provide suggestions for how incorporating genetic analyses can ease confusion and help define ecotypes. We approach this by systematically reviewing 112 publications across taxa that simultaneously mention the terms ecotype, conservation and management, to examine the current use of the term in the context of conservation and management. We found that most ecotype studies involve fish, mammals and plants with a focus on habitat use, which at 60% was the most common criterion used for categorization of ecotypes. Only 53% of the studies incorporated genetic analyses, and major discrepancies in available genomic resources among taxa could have contributed to confusion about the role of genetic structure in delineating ecotypes. Our results show that the rapid advances in genetic methods, also for nonmodel organisms, can help clarify the spatiotemporal distribution of adaptive and neutral genetic variation and their relevance to ecotype designations. Genetic analyses can offer empirical support for the ecotype concept and provide a timely measure of evolutionary potential, especially in changing environmental conditions. Genetic variation that is often difficult to detect, including polygenic traits influenced by small contributions from several genes, can be vital for adaptation to rapidly changing environments. Emerging ecotypes may signal speciation in progress, and findings from genome-enabled organisms can help clarify important selective factors driving ecotype development and persistence, and thereby improve preservation of interspecific genetic diversity. Incorporation of genetic analyses in ecotype studies will help connect evolutionary biology and applied conservation, including that of problematic groups such as natural hybrid organisms and urban or anthropogenic ecotypes.
ABSTRACT
Parasites are integral to ecosystem functioning yet often overlooked. Improved understanding of host-parasite associations is important, particularly for wide-ranging species for which host range shifts and climate change could alter host-parasite interactions and their effects on ecosystem function.Among the most widely distributed mammals with diverse diets, gray wolves (Canis lupus) host parasites that are transmitted among canids and via prey species. Wolf-parasite associations may therefore influence the population dynamics and ecological functions of both wolves and their prey. Our goal was to identify large-scale processes that shape host-parasite interactions across populations, with the wolf as a model organism.By compiling data from various studies, we examined the fecal prevalence of gastrointestinal parasites in six wolf populations from two continents in relation to wolf density, diet diversity, and other ecological conditions.As expected, we found that the fecal prevalence of parasites transmitted directly to wolves via contact with other canids or their excreta was positively associated with wolf density. Contrary to our expectations, the fecal prevalence of parasites transmitted via prey was negatively associated with prey diversity. We also found that parasite communities reflected landscape characteristics and specific prey items available to wolves.Several parasite taxa identified in this study, including hookworms and coccidian protozoans, can cause morbidity and mortality in canids, especially in pups, or in combination with other stressors. The density-prevalence relationship for parasites with simple life cycles may reflect a regulatory role of gastrointestinal parasites on wolf populations. Our result that fecal prevalence of parasites was lower in wolves with more diverse diets could provide insight into the mechanisms by which biodiversity may regulate disease. A diverse suite of predator-prey interactions could regulate the effects of parasitism on prey populations and mitigate the transmission of infectious agents, including zoonoses, spread via trophic interactions.
ABSTRACT
The social license to operate framework considers how society grants or withholds informal permission for resource extractors to exploit publicly owned resources. We developed a modified model, which we refer to as the social license to hunt (SLH). In it we similarly consider hunters as operators, given that wildlife are legally considered public resources in North America and Europe. We applied the SLH model to examine the controversial hunting of large carnivores, which are frequently killed for trophies. Killing for trophies is widespread, but undertaken by a minority of hunters, and can pose threats to the SLH for trophy-seeking carnivore hunters and potentially beyond. Societal opposition to large carnivore hunting relates not only to conservation concerns but also to misalignment between killing for trophies and dominant public values and attitudes concerning the treatment of animals. We summarized cases related to the killing of grizzly bears (Ursus arctos), wolves (Canis lupus), and other large carnivores in Canada, the United States, and Europe to illustrate how opposition to large carnivore hunting, now expressed primarily on social media, can exert rapid and significant pressure on policy makers and politicians. Evidence of the potential for transformative change to wildlife management and conservation includes proposed and realized changes to legislation, business practice, and wildlife policy, including the banning of some large carnivore hunts. Given that policy is ultimately shaped by societal values and attitudes, research gaps include developing increased insight into public support of various hunting policies beyond that derived from monitoring of social media and public polling. Informed by increased evidence, the SLH model can provide a conceptual foundation for predicting the likelihood of transient versus enduring changes to wildlife conservation policy and practice for a wide variety of taxa and contexts.
Cacería de Grandes Carnívoros y la Licencia Social para Cazar Resumen El marco de trabajo de la licencia social para operar considera cómo la sociedad otorga o restringe permisos informales para que los extractores de recursos puedan explotar los recursos públicos. Desarrollamos un modelo modificado, al cual nos referimos como la licencia social para cazar (LSC). En este modelo consideramos a los cazadores como símiles de los operadores puesto que en América del Norte y en Europa a la fauna se le considera legalmente como recurso público. Aplicamos el modelo de la LSC en un análisis de la cacería controversial de grandes carnívoros, a los cuales con frecuencia se les caza para convertirlos en trofeos. La cacería para trofeos es común pero sólo la realiza una minoría de los cazadores y puede presentar una amenaza para la LSC para los cazadores que cazan carnívoros para trofeos e incluso para otros tipos de cazadores. La oposición social a la cacería de grandes carnívoros se relaciona no sólo con el interés de conservación sino también con la discordancia entre la caza para trofeos y las actitudes y valores públicos dominantes con respecto al trato hacia los animales. Resumimos algunos casos relacionados con la muerte de osos pardos (Ursus arctos), lobos (Canis lupus) y otros grandes carnívoros en Canadá, los Estados Unidos y Europa para mostrar cómo la oposición a la cacería de grandes carnívoros, hoy en día expresada principalmente en las redes sociales, puede ejercer una presión rápida y significativa sobre los políticos y los formuladores de políticas. La evidencia de un potencial de cambio transformador en el manejo y conservación de fauna incluye los cambios propuestos y realizados a la legislación, la práctica comercial y las políticas para la fauna, incluyendo la prohibición de la caza de algunos grandes carnívoros. Ya que las políticas están finalmente moldeadas por las actitudes y los valores sociales, las lagunas en la investigación incluyen el desarrollo de un conocimiento mejorado del respaldo público para varias políticas de cacería más allá del conocimiento derivado del monitoreo de las redes sociales y las encuestas públicas. Si se informa con mucha más evidencia, el modelo de la LSC puede proporcionar una base conceptual para predecir la probabilidad de los cambios transitorios versus los duraderos en las políticas y las prácticas de conservación de fauna para una gama amplia de taxones y contextos.
Subject(s)
Carnivora , Ursidae , Wolves , Animals , Animals, Wild , Conservation of Natural ResourcesABSTRACT
[This corrects the article DOI: 10.1371/journal.pbio.3000193.].
ABSTRACT
AIM: The influence of humans on large carnivores, including wolves, is a worldwide conservation concern. In addition, human-caused changes in carnivore density and distribution might have impacts on prey and, indirectly, on vegetation. We therefore tested wolf responses to infrastructure related to natural resource development (i.e., human footprint). LOCATION: Our study provides one of the most extensive assessments of how predators like wolves select habitat in response to various degrees of footprint across boreal ecosystems encompassing over a million square kilometers of Canada. METHODS: We deployed GPS-collars on 172 wolves, monitored movements and used a generalized functional response (GFR) model of resource selection. A functional response in habitat selection occurs when selection varies as a function of the availability of that habitat. GFRs can clarify how human-induced habitat changes are influencing wildlife across large, diverse landscapes. RESULTS: Wolves displayed a functional response to footprint. Wolves were more likely to select forest harvest cutblocks in regions with higher cutblock density (i.e., a positive functional response to high-quality habitats for ungulate prey) and to select for higher road density in regions where road density was high (i.e., a positive functional response to human-created travel routes). Wolves were more likely to use cutblocks in habitats with low road densities, and more likely to use roads in habitats with low cutblock densities, except in winter when wolves were more likely to use roads regardless of cutblock density. MAIN CONCLUSIONS: These interactions suggest that wolves trade-off among human-impacted habitats, and adaptively switch from using roads to facilitate movement (while also risking encounters with humans), to using cutblocks that may have higher ungulate densities. We recommend that conservation managers consider the contextual and interacting effects of footprints when assessing impacts on carnivores. These effects likely have indirect impacts on ecosystems too, including on prey species.
ABSTRACT
Despite abundant focus on responsible care of laboratory animals, we argue that inattention to the maltreatment of wildlife constitutes an ethical blind spot in contemporary animal research. We begin by reviewing significant shortcomings in legal and institutional oversight, arguing for the relatively rapid and transformational potential of editorial oversight at journals in preventing harm to vertebrates studied in the field and outside the direct supervision of institutions. Straightforward changes to animal care policies in journals, which our analysis of 206 journals suggests are either absent (34%), weak, incoherent, or neglected by researchers, could provide a practical, effective, and rapidly imposed safeguard against unnecessary suffering. The Animals in Research: Reporting On Wildlife (ARROW) guidelines we propose here, coupled with strong enforcement, could result in significant changes to how animals involved in wildlife research are treated. The research process would also benefit. Sound science requires animal subjects to be physically, physiologically, and behaviorally unharmed. Accordingly, publication of methods that contravenes animal welfare principles risks perpetuating inhumane approaches and bad science.
Subject(s)
Animal Experimentation/ethics , Animal Welfare/ethics , Animals, Wild/psychology , Animals , Animals, Laboratory , Conservation of Natural Resources/methods , Humans , Publications , Publishing , Research PersonnelABSTRACT
Resource waves-spatial variation in resource phenology that extends feeding opportunities for mobile consumers-can affect the behaviour and productivity of recipient populations. Interspecific diversity among Pacific salmon species (Oncorhynchus spp.) creates staggered spawning events across space and time, thereby prolonging availability to terrestrial wildlife. We sought to understand how such variation might influence consumption by terrestrial predators compared with resource abundance and intra- and interspecific competition. Using stable isotope analysis, we investigated how the proportion of salmon in the annual diet of male black bears (Ursus americanus; n = 405) varies with species diversity and density of spawning salmon biomass, while also accounting for competition with sympatric black and grizzly bears (U. arctos horribilis), in coastal British Columbia, Canada. We found that the proportion of salmon in the annual diet of black bears was ≈40% higher in the absence of grizzly bears, but detected little effect of relative black bear density and salmon biomass density. Rather, salmon diversity had the largest positive effect on consumption. On average, increasing diversity from one salmon species to ~four (with equal biomass contributions) approximately triples the proportion of salmon in diet. Given the importance of salmon to bear life histories, this work provides early empirical support for how resource waves may increase the productivity of consumers at population and landscape scales. Accordingly, terrestrial wildlife management might consider maintaining not only salmon abundance but also diversity.
Subject(s)
Salmonidae , Ursidae , Animals , Animals, Wild , British Columbia , Male , SalmonABSTRACT
Admixture resulting from natural dispersal processes can potentially generate novel phenotypic variation that may facilitate persistence in changing environments or result in the loss of population-specific adaptations. Yet, under the US Endangered Species Act, policy is limited for management of individuals whose ancestry includes a protected taxon; therefore, they are generally not protected under the Act. This issue is exemplified by the recently re-established grey wolves of the Pacific Northwest states of Washington and Oregon, USA. This population was likely founded by two phenotypically and genetically distinct wolf ecotypes: Northern Rocky Mountain (NRM) forest and coastal rainforest. The latter is considered potentially threatened in southeast Alaska and thus the source of migrants may affect plans for their protection. To assess the genetic source of the re-established population, we sequenced a ~ 300 bp portion of the mitochondrial control region and ~ 5 Mbp of the nuclear genome. Genetic analysis revealed that the Washington wolves share ancestry with both wolf ecotypes, whereas the Oregon population shares ancestry with NRM forest wolves only. Using ecological niche modelling, we found that the Pacific Northwest states contain environments suitable for each ecotype, with wolf packs established in both environmental types. Continued migration from coastal rainforest and NRM forest source populations may increase the genetic diversity of the Pacific Northwest population. However, this admixed population challenges traditional management regimes given that admixture occurs between an adaptively distinct ecotype and a more abundant reintroduced interior form. Our results emphasize the need for a more precise US policy to address the general problem of admixture in the management of endangered species, subspecies, and distinct population segments.
Subject(s)
Endangered Species , Wolves/growth & development , Animal Distribution , Animals , Breeding , Conservation of Natural Resources , Ecosystem , Endangered Species/statistics & numerical data , Female , Genotype , Male , Northwestern United States , Population Dynamics , Wolves/classification , Wolves/genetics , Wolves/physiologyABSTRACT
Mawdsley et al. (2018) respond disapprovingly to our 2018 review of 667 wildlife management systems across Canada and the United States, which found that many of these systems lacked the scientific hallmarks of clear objectives, evidence, transparency, and independent review. Although we strongly agree with several of Mawdsley et al.'s points about the role of science in management, their response suggests confusion about three elements of our approach that we clarify herein: (i) the selection of hallmarks, (ii) the role of science in wildlife management, and (iii) our engagement with wildlife agencies. We contend that both critics and defenders of the current approach to wildlife management in Canada and the United States similarly desire rigorous management that achieves social and ecological benefits. Our original study-which used a clear approach to define hallmarks of science-based management, employed a reasonable set of indicator criteria to test for them, and was based on data available to the general public on whose behalf management is conducted-found evidence that the current approach falls short. However, it also provided a framework for addressing shortcomings moving forward. We suggest that advancing discussion on the operational role of science in management, including clarifying what "science-based management" actually means, could curtail practitioners and critics of the status quo talking over each other's heads and encourage all parties to work constructively to improve the governance of wildlife at a continental scale.
Subject(s)
Animals, Wild/physiology , Conservation of Natural Resources , Animals , Communication , Humans , North America , Public Opinion , Science , United StatesABSTRACT
Resource management agencies commonly defend controversial policy by claiming adherence to science-based approaches. For example, proponents and practitioners of the "North American Model of Wildlife Conservation," which guides hunting policy across much of the United States and Canada, assert that science plays a central role in shaping policy. However, what that means is rarely defined. We propose a framework that identifies four fundamental hallmarks of science relevant to natural resource management (measurable objectives, evidence, transparency, and independent review) and test for their presence in hunt management plans created by 62 U.S. state and Canadian provincial and territorial agencies across 667 management systems (species-jurisdictions). We found that most (60%) systems contained fewer than half of the indicator criteria assessed, with more criteria detected in systems that were peer-reviewed, that pertained to "big game," and in jurisdictions at increasing latitudes. These results raise doubt about the purported scientific basis of hunt management across the United States and Canada. Our framework provides guidance for adopting a science-based approach to safeguard not only wildlife but also agencies from potential social, legal, and political conflict.
Subject(s)
Animals, Wild/physiology , Conservation of Natural Resources , Science , Animals , Canada , Communication , United StatesABSTRACT
The original Article mistakenly coded the constitutional rights of Australia as containing a governmental duty to protect the environment (blue in the figures); this has been corrected to containing no explicit mention of environmental protection (orange in the figures). The original Article also neglected to code the constitutional rights of the Cayman Islands (no data; yellow in the figures); this has been corrected to containing a governmental duty to protect the environment (blue in the figures).Although no inferences changed as a result of these errors, many values changed slightly and have been corrected. The proportion of the world's nations having constitutional rights to a healthy environment changed from 75% to 74%. The proportions of nations in different categories given in the Fig. 1 caption all changed except purple countries (3.1%): green countries changed from 47.2% to 46.9%; blue countries changed from 24.4% to 24.2%; and orange countries changed from 25.3% to 25.8%. The proportion of the global atmospheric CO2 emitted by the 144 nations changed from 72.6% to 74.4%; the proportion of the world's population represented by the 144 nations changed from 84.9% to 85%. The values of annual average CO2 emissions for blue countries changed from 363,000 Gg to 353,000 Gg and for orange countries from 195,000 Gg to 201,000 Gg. The proportion of threatened mammals endemic to a single country represented by the 144 countries changed from 91% to 84%. Figures 1-3 have been updated to show the correct values and map colours and the Supplementary Information has been updated to give the correct country codes.
ABSTRACT
Understanding cumulative effects of multiple threats is key to guiding effective management to conserve endangered species. The critically endangered, Southern Resident killer whale population of the northeastern Pacific Ocean provides a data-rich case to explore anthropogenic threats on population viability. Primary threats include: limitation of preferred prey, Chinook salmon; anthropogenic noise and disturbance, which reduce foraging efficiency; and high levels of stored contaminants, including PCBs. We constructed a population viability analysis to explore possible demographic trajectories and the relative importance of anthropogenic stressors. The population is fragile, with no growth projected under current conditions, and decline expected if new or increased threats are imposed. Improvements in fecundity and calf survival are needed to reach a conservation objective of 2.3% annual population growth. Prey limitation is the most important factor affecting population growth. However, to meet recovery targets through prey management alone, Chinook abundance would have to be sustained near the highest levels since the 1970s. The most optimistic mitigation of noise and contaminants would make the difference between a declining and increasing population, but would be insufficient to reach recovery targets. Reducing acoustic disturbance by 50% combined with increasing Chinook by 15% would allow the population to reach 2.3% growth.
Subject(s)
Conservation of Natural Resources/methods , Endangered Species , Human Activities , Whale, Killer , AnimalsABSTRACT
Human-wildlife conflicts impose considerable costs to people and wildlife worldwide. Most research focuses on proximate causes, offering limited generalizable understanding of ultimate drivers. We tested three competing hypotheses (problem individuals, regional population saturation, limited food supply) that relate to underlying processes of human-grizzly bear (Ursus arctos horribilis) conflict, using data from British Columbia, Canada, between 1960-2014. We found most support for the limited food supply hypothesis: in bear populations that feed on spawning salmon (Oncorhynchus spp.), the annual number of bears/km(2) killed due to conflicts with humans increased by an average of 20% (6-32% [95% CI]) for each 50% decrease in annual salmon biomass. Furthermore, we found that across all bear populations (with or without access to salmon), 81% of attacks on humans and 82% of conflict kills occurred after the approximate onset of hyperphagia (July 1(st)), a period of intense caloric demand. Contrary to practices by many management agencies, conflict frequency was not reduced by hunting or removal of problem individuals. Our finding that a marine resource affects terrestrial conflict suggests that evidence-based policy for reducing harm to wildlife and humans requires not only insight into ultimate drivers of conflict, but also management that spans ecosystem and jurisdictional boundaries.