Saving large carnivores, but losing the apex predator?

AbstractLarge terrestrial carnivores, e.g. wolves or bears, often play a key ecological role from their position at the apex of trophic systems. Changes to their populations reverberate through ecological communities; consequently their widespread decline in numbers and shrinking distribution due to human persecution has brought about a loss and reconfiguration of biological diversity in many systems. Although many large carnivore populations are now under conservation-minded management, political and economic constraints make compromises necessary. A common compromise is to permit limited harvests, with the premise of sustainability and the objective to increase tolerance and funding for carnivore recovery and conservation. Here we question whether a large carnivore that has to “look over its shoulder” for human hunters can still fully perform its ecological role at the apex of a trophic system. We use information about carnivore behavior, ecology, trophic interactions, and the effects of human exploitation to argue that exploitation of large carnivores, even if sustainable numerically, undermines the commonly expressed rationale for their conservation, namely the restoration and preservation of ecosystem functionality. Our argument centers around (i) the necessity of behavioral adjustments in large carnivores to anthropomorphic risk, which may limit their contribution to the “landscape of fear”, and (ii) the observation that many of the same features that put large carnivores at the apex of trophic systems also make them vulnerable to human exploitation and persecution, with implicit consequences for their ecological functionality and evolution. Although hunting large carnivores can improve public acceptance, managers must be aware of the trade-offs

Los animales como reservorios de enfermedades

Los animales salvajes pueden actuar como reservorios de patógenos (virus, bacterias, protozoos y hongos) potencialmente peligrosos para el ser humano. De hecho, la gran mayoría de las enfermedades emergentes son zoonosis (es decir, son transmitidas por animales) y todo apunta a que el nuevo SARS-CoV-2, el virus responsable de la actual pandemia de coronavirus, se haya transmitido a los seres humanos de un reservorio animal (concretamente de los murciélagos). Conocer los reservorios animales y su distribución, a la vez que los factores que facilitan el contacto con los seres humanos y la transmisión de patógenos, es fundamental para la prevención de brotes de enfermedades. En este artículo analizamos la literatura disponible para identificar los grupos animales que representan los principales reservorios de zoonosis y los factores, tales como riqueza de especies, características fisiológicas, ecológicas o proximidad genética al ser humano, que aumentan la probabilidad de brotes zoonóticos. En particular, analizaremos el papel de roedores y murciélagos, que representan en la actualidad los dos principales reservorios de zoonosis

Recolonization following past persecution questions the importance of persistent snow cover as a range limiting factor for wolverines

Globally, climate is changing rapidly, which causes shifts in many species' distributions, stressing the need to understand their response to changing environmental conditions to inform conservation and management. Northern latitudes are expected to experience strongest changes in climate, with milder winters and decreasing snow cover. The wolverine (Gulo gulo) is a circumpolar, threatened carnivore distributed in northern tundra, boreal, and subboreal habitats. Previous studies have suggested that wolverine distribution and reproduction are constrained by a strong association with persistent spring snow cover. We assess this hypothesis by relating spatial distribution of 1589 reproductive events, a fitness-related proxy for female reproduction and survival, to snow cover over two decades. Wolverine distribution has increased and number of reproductive events increased 20 times in areas lacking spring snow cover during our study period, despite low monitoring effort where snow is sparse. Thus, the relationship between reproductive events and persistent spring snow cover weakened during this period. These findings show that wolverine reproductive success and hence distribution are less dependent on spring snow cover than expected. This has important implications for projections of future habitat availability, and thus distribution, of this threatened species. Our study also illustrates how past persecution, or other factors, that have restricted species distribution to remote areas can mask actual effects of environmental parameters, whose importance reveals when populations expand beyond previously restricted ranges. Overwhelming evidence shows that climate change is affecting many species and ecological processes, but forecasting potential consequences on a given species requires longitudinal data to revisit hypotheses and reassess the direction and magnitude of climate effects with new data. This is especially important for conservation-oriented management of species inhabiting dynamic systems where environmental factors and human activities interact, a common scenario for many species in different ecosystems around the globe

Effects of Human Disturbance on Terrestrial Apex Predators

The effects of human disturbance spread over virtually all ecosystems and ecological communities on Earth. In this review, we focus on the effects of human disturbance on terrestrial apex predators. We summarize their ecological role in nature and how they respond to different sources of human disturbance. Apex predators control their prey and smaller predators numerically and via behavioral changes to avoid predation risk, which in turn can affect lower trophic levels. Crucially, reducing population numbers and triggering behavioral responses are also the effects that human disturbance causes to apex predators, which may in turn influence their ecological role. Some populations continue to be at the brink of extinction, but others are partially recovering former ranges, via natural recolonization and through reintroductions. Carnivore recovery is both good news for conservation and a challenge for management, particularly when recovery occurs in human-dominated landscapes. Therefore, we conclude by discussing several management considerations that, adapted to local contexts, may favor the recovery of apex predator populations and their ecological functions in nature

Individual variation in predatory behavior, scavenging and seasonal prey availability as potential drivers of coexistence between wolves and bears

Several large carnivore populations are recovering former ranges, and it is important to understand interspecific interactions between overlapping species. In Scandinavia, recent research has reported that brown bear presence influences gray wolf habitat selection and kill rates. Here, we characterized the temporal use of a common prey resource by sympatric wolves and bears and described individual and seasonal variation in their direct and/or indirect interactions. Most bear–wolf interactions were indirect, via bear scavenging of wolf kills. Bears used >50% of wolf kills, whereas we did not record any wolf visit at bear kills. Adult and subadult bears visited wolf kills, but female bears with cubs of the year, the most vulnerable age class to conspecifics and other predators, did not. Wolf and bear kill rates peaked in early summer, when both targeted neonate moose calves, which coincided with a reduction in bear scavenging rate. Some bears were highly predatory and some did not kill any calf. Individual and age-class variation (in bear predation and scavenging patterns) and seasonality (in bear scavenging patterns and main prey availability of both wolves and bears) could mediate coexistence of these apex predators. Similar processes likely occur in other ecosystems with varying carnivore assemblages

Large carnivore conservation and traditional pastoralism: A case study on bear–reindeer predation mitigation measures

While wildlife and cultural preservation goals can be either complimentary or counteractive, the goals of large carnivore conservation and traditional pastoralist lifestyles are often at odds. Livestock depredation can negatively impact the economies of livestock herders, while subsequent lethal removals contribute to local carnivore population declines. Here, we collaborated with two Sámi reindeer herding communities (2010–2016) situated in Sweden's boreal forest to evaluate the efficacy and economic feasibility of three brown bear predation mitigation measures: corralling pregnant reindeer during parturition, lethal bear management removals, and public bear-license hunting. Calving corrals increased survival for reindeer calves born to average-sized females by 7%–15%, and by 14%–30% for calves born to small females. However, the realized cost of implementing calving corrals outweighed the financial gain for both our study areas (net losses ranged between €1111 and €6210 per calf saved from bear predation per year when using the updated 2021 calf value; 1€ [Euro] = US$1.1), as well as for almost every theoretical scenario we explored (net losses €234 and €13,995 per calf saved from bear predation). The exception was the theoretical scenario where small herding communities overlapped large bear populations, which crossed the breakeven efficacy bear/reindeer ratio of 13.5 bears/100 reindeer and had a potential net gain of €36 per saved calf. Similarly, the cost of lethal management removals of bears outweighed the potential financial gain from saved calves, with net losses between €75 and €239 per calf. License hunting, where the hunters voluntarily incur the monetary costs of removing bears, is in most cases the only economically viable mitigation measure where the cost of mitigation did not outweigh the financial gain from increased reindeer survival. While the annual public license hunt was the most cost-effective mitigation measure, it may be less biologically effective, that is, bear hunting occurs in the fall and reindeer parturition the following spring which leaves time for the empty niche of harvested bears to be filled by survivors. Economically and biologically effective predation mitigation measures are key for promoting coexistence, and we suggest that potential mitigation measures should be studied in collaboration with local people

Large carnivore conservation and traditional pastoralism: A case study on bear–reindeer predation mitigation measures

While wildlife and cultural preservation goals can be either complimentary orcounteractive, the goals of large carnivore conservation and traditional pastoralist lifestyles are often at odds. Livestock depredation can negatively impact the economies of livestock herders, while subsequent lethal removals contribute to local carnivore population declines. Here, we collaborated with two Sami reindeer herding communities (2010–2016) situated in Sweden’s boreal forest to evaluate the efficacy and economic feasibility of three brown bear predation mitigation measures: corralling pregnant reindeer during parturition, lethal bear management removals, and public bear-license hunting. Calving corrals increased survival for reindeer calves born to average-sized females by 7%–15%, and by 14%–30% for calves born to small females. However, the realized cost of implementing calving corrals outweighed the financial gain for both our study areas (net losses ranged between €1111 and €6210 per calf saved from bear predation per year when using the updated 2021 calf value; 1€ [Euro] = US$1.1), as well as for almost every theoretical scenario we explored (net losses €234 and €13,995 per calf saved from bear predation). The exception was the theoretical scenario where small herding communities overlapped large bear populations, which crossed the breakeven efficacy bear/reindeer ratio of 13.5 bears/100 reindeer and had a potential net gain of €36 per saved calf. Similarly, the cost of lethal management removals of bears outweighed the potential financial gain from saved calves, with net losses between €75 and €239 per calf. License hunting, where the hunters voluntarily incur the monetary costs of removing bears, is in most cases the only economically viable mitigation measure where the cost of mitigation did not outweigh the financial gain from increased reindeer survival. While the annual public license hunt was the most cost-effective mitigation measure, it may be less biologically effective, that is, bear hunting occurs in the fall and reindeer parturition the following spring which leaves time for the empty niche of harvested bears to be filled by survivors. Economically and biologically effective predation mitigation measures are key for promoting coexistence, and we suggest that potential mitigation measures should be studied in collaboration with local people. brown bear, calving corrals, economic feasibility, management removal, predation, reindeer herdingpublishedVersio

Brown bear behaviour in human-modified landscapes: The case of the endangered Cantabrian population, NW Spain

Large carnivores are recolonizing parts of their historical range in Europe, a heavily modified human landscape. This calls for an improvement of our knowledge on how large carnivores manage to coexist with humans, and on the effects that human activity has on large carnivore behaviour, especially in areas where carnivore populations are still endangered. Brown bears Ursus arctos have been shown to be sensitive to the presence of people and their activities. Thus, bear conservation and management should take into account potential behavioural alterations related to living in human-modified landscapes. We studied the behaviour of brown bears in the Cantabrian Mountains, NW Spain, where an endangered population thrives in a human-modified landscape. We analysed bear observations video-recorded over a 10-year period to try to identify human and landscape elements that could influence bear behaviour. Neither the occurrence nor the duration of vigilance behaviour in Cantabrian bears seemed to be influenced by the proximity of human infrastructures and activity. Our findings suggest that the general pattern of human avoidance by bears is adapted to the human-modified landscape they inhabit. Bears generally avoid people, but close presence of human infrastructures or activity did not seem to trigger an increased bear behavioural response. Coexistence between large carnivores and humans in human-modified landscapes is possible, even when human encroachment is high, provided that carnivores are not heavily persecuted and direct interactions are avoided. Further research should also document the potential existence of other responses to human presence and activity, e.g., hunting, traffic noise, and measuring stress levels with physiological indicators.This research was financially supported by the IBA (International Association for Bear Research and Management) grant project IBA-RG_16_2016 ‘Brown bear behaviour in human-dominated landscapes: the effect of human density and ecotourism’. During this research, G.B. was financially supported by a collaboration contract with the MUSE – Museo delle Scienze of Trento (Italy), J.M-P. was supported by the ARAID foundation and V.P., A.O. and R.G.G. were also financially supported by the Excellence Project CGL2017-82782-P financed by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO), the Agencia Estatal de Investigación (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER, EU)

Bears in Human-Modified Landscapes: The Case Studies of the Cantabrian, Apennine, and Pindos Mountains

Edited by Vincenzo Penteriani and Mario Melletti.-- Part III - Human–Bear Coexistence.-- This material has been published in "Bears of the World. Ecology, Conservation and Management" by / edited by Vincenzo Penteriani and Mario Melletti / Cambridge University Press. This version is free to view and download for personal use only. Not for re-distribution, re-sale or use in derivative works.Brown bears Ursus arctos were historically persecuted and almost eradicated from southern Europe in the twentieth century as a result of hunting and direct persecution. The effects of human-induced mortality were exacerbated by other threats, such as habitat loss and fragmentation, due to the expansion of human populations. As a result, nowadays there are only small fragmented populations of bears in southern Europe. Brown bears in the Cantabrian (north-western Spain), Apennine (central Italy), and Pindos (north-western Greece) mountains represent three examples of small and threatened bear populations in human-modified landscapes. Most of their range is characterized by high human densities, widespread agricultural activities, livestock raising and urban development, connected by dense networks of transport infrastructures. This has resulted in a reduction of continuous habitat suitable for the species. Here, we summarize the past and present histories and fates of these three populations as examples on how the coexistence of bears and people in human-modified landscapes can take different turns depending on human attitudes