The future role of large carnivores in terrestrial trophic interactions: the northern temperate view (original) (raw)
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Status and Ecological Effects of the World’s Largest Carnivores
Science, 2014
Large carnivores face serious threats and are experiencing massive declines in their populations and geographic ranges around the world. We highlight how these threats have affected the conservation status and ecological functioning of the 31 largest mammalian carnivores on Earth. Consistent with theory, empirical studies increasingly show that large carnivores have substantial effects on the structure and function of diverse ecosystems. Significant cascading trophic interactions, mediated by their prey or sympatric mesopredators, arise when some of these carnivores are extirpated from or repatriated to ecosystems. Unexpected effects of trophic cascades on various taxa and processes include changes to bird, mammal, invertebrate, and herpetofauna abundance or richness; subsidies to scavengers; altered disease dynamics; carbon sequestration; modified stream morphology; and crop damage. Promoting tolerance and coexistence with large carnivores is a crucial societal challenge that will ultimately determine the fate of Earth’s largest carnivores and all that depends upon them, including humans.
Lack of Cascading Effects of Eurasian Lynx Predation on Roe Deer to Soil and Plant Nutrients
Diversity, 2020
This study examines the extent to which above-ground trophic processes such as large carnivore predation on wild ungulates can cause cascading effects through the provision of carrion resources to below-ground ecosystem processes in the boreal forest of southeastern Norway. We measured the levels of 10 parameters in soil samples and 7 parameters in vegetation (wavy hair-grass, Avenella flexuosa, and bilberry, Vaccinium myrtillus) at 0, 0.5 and 2 m distance from 18 roe deer (Capreolus caprelous) carcasses killed by Eurasian lynx (Lynx lynx). We then compared these values to two control sites 20 m away from each carcass. Sampling was conducted 20–29 months after death. Neither soil nor vegetation samples showed a clear gradient in parameters (CN, NH4+, NO3−, P, PO4−, Ca, K, Mg and Na) from the center of a carcass towards the periphery. Similarly, there was no difference in the effect on soil and vegetation between winter- and summer-killed carcasses. Our results contrast with that of ...
Only the largest terrestrial carnivores increase their dietary breadth with increasing prey richness
Mammal Review, 2020
1. Animals should adapt their foraging habits, changing their dietary breadth in response to variation in the richness and availability of food resources. Understanding how species modify their dietary breadth according to variation in resource richness would support predictions of their responses to environmental changes that alter prey communities. 2. We evaluated relationships between the dietary breadth of large terrestrial carnivores and the local richness of large prey (defined as the number of species). We tested alternative predictions suggested by ecological and evolutionary theories: with increasing prey richness, species would (1) show a more diverse diet, thus broadening their dietary breadth, or (2) narrow their dietary breadth, indicating specialisation on a smaller number of prey. 3. We collated data from 505 studies of the diets of 12 species of large terrestrial mammalian carnivores to model relationships between two indices of dietary breadth and local prey richness. 4. For the majority of species, we found no evidence for narrowing dietary breadth (i.e. increased specialisation) with increasing prey richness. Although the snow leopard and the dhole appeared to use a lower number of large prey species with increasing prey richness, larger sample sizes are needed to support this result. 5. With increasing prey richness, the five largest carnivores (puma Puma concolor, spotted hyaena Crocuta crocuta, jaguar Panthera onca, lion Panthera leo, and tiger Panthera tigris), plus the Eurasian lynx Lynx lynx and the grey wolf Canis lupus (which are usually top predators in the areas from which data were obtained), showed greater dietary breadth and/or used a greater number of large prey species (i.e. increased generalism). 6. We suggest that dominant large carnivores encounter little competition in expanding their dietary breadth with increasing prey richness; conversely, the dietary niche of subordinate large carnivores is limited by competition with larger, dominant predators. We suggest that, over evolutionary time, resource Mammal Review
Large impact of eurasian lynx predation on roe deer population dynamics
PloS one, 2015
The effects of predation on ungulate populations depend on several factors. One of the most important factors is the proportion of predation that is additive or compensatory respectively to other mortality in the prey, i.e., the relative effect of top-down and bottom-up processes. We estimated Eurasian lynx (Lynx lynx) kill rate on roe deer (Capreolus capreolus) using radio-collared lynx. Kill rate was strongly affected by lynx social status. For males it was 4.85 ± 1.30 S.E. roe deer per 30 days, for females with kittens 6.23 ± 0.83 S.E. and for solitary females 2.71 ± 0.47 S.E. We found very weak support for effects of prey density (both for Type I (linear) and Type II (non-linear) functional responses) and of season (winter, summer) on lynx kill rate. Additionally, we analysed the growth rate in a roe deer population from 1985 to 2005 in an area, which lynx naturally re-colonized in 1996. The annual roe deer growth rate was lower after lynx re-colonized the study area, but it was...
European Journal of Wildlife Research, 2014
Human harvest is the most important mortality factor for wild ungulates in Europe and can affect several aspects of ungulate biology. There is a growing concern about possible negative sideeffects of human harvest. To better understand differences between human and natural mortality we compared the extent, age and sex structure, nutritional condition, spatial and temporal distribution of human harvest and natural predation by the Eurasian lynx Lynx lynx on the European roe deer Capreolus capreolus, the most abundant wild ungulate in Europe. Compared to the human harvest, lynx were less likely to kill fawns and yearlings than adults, and among adult deer lynx were more likely to kill females. Proportion of roe deer with fat-depleted bone marrow was higher among lynx prey than among harvested animals. Average lynx kill rate was estimated to 47.8 roe deer / year and lynx predation was considerably lower than the human harvest in the same area. While human harvest increased with higher roe deer density, lynx predation was similar across the gradient of roe deer densities. Comparison with other countries indicated that differences between human harvest and natural mortality of ungulates vary considerably in different parts of Europe. Variation in hunting practices and, even more importantly, carnivore predation may have an important role in buffering unwanted side-effects of harvest of wild ungulates.
Habitat differentiation within the large‐carnivore community of Norway's multiple‐use landscapes
Journal of Applied …, 2008
The re-establishment of large carnivores in Norway has led to increased conflicts and the adoption of regional zoning for these predators. When planning the future distribution of large carnivores, it is important to consider details of their potential habitat tolerances and strength of inter-specific differentiation. We studied differentiation in habitat and kill sites within the large-carnivore community of south-eastern Norway.We compared habitat selection of the brown bear Ursus arctos L., Eurasian lynx Lynx lynx L., wolf Canis lupus L. and wolverine Gulo gulo L., based on radio-tracking data. Differences in kill site locations were explored using locations of documented predator-killed sheep Ovis aries L. We modelled each species’ selection for, and differentiation in, habitat and kill sites on a landscape scale using resource selection functions and multinomial logistic regression. Based on projected probability of occurrence maps, we estimated continuous patches of habitat within the study area.Although bears, lynx, wolves and wolverines had overlapping distributions, we found a clear differentiation for all four species in both habitat and kill sites. The presence of bears, wolves and lynx was generally associated with rugged, forested areas at lower elevations, whereas wolverines selected rugged terrain at higher elevations. Some degree of sympatry was possible in over 40% of the study area, although only 1·5% could hold all four large carnivores together.Synthesis and applications. A geographically differentiated management policy has been adopted in Norway, aimed at conserving viable populations of large carnivores while minimizing the potential for conflicts. Sympatry of all four carnivores will be most successful if regional zones are established of adequate size spanning an elevational gradient. High prey densities, low carnivore densities, low dietary overlap and scavenging opportunities have most probably led to reduced competitive exclusion. Although regional sympatry enhances the conservation of an intact guild of large carnivores, it may well increase conflict levels and resistance to carnivore conservation locally.
Frontiers in Ecology and Evolution
Carnivores act as top-down regulators in terrestrial ecosystems, and their occurrence and relative abundance is a result of complex interactions between food and habitat availability, human pressure (e.g., trapping, hunting, roadkill), and intraguild interactions (competition, predation). Eastern United States has a long history of human impact, which resulted in an altered carnivore community. Specifically, Ohio presents an interesting case for evaluating the relative roles of interspecific relations and habitat characteristics for shaping the carnivore community, as its carnivore community has a unique dynamics and composition: invasive coyote and red fox (Vulpes vulpes), and native bobcat (Lynx rufus), currently recovering and expanding its range, gray fox (Urocyon cinereoargenteus) declining at a fast pace, and the generalist raccoon (Procyon lotor) and Virginian opossum (Didelphis virginiana). We used 50 camera traps to collect presence/absence data in southeastern Ohio, USA. We hypothesized potential interactions between the six carnivores, and used land cover variables, as well as occupancy probabilities of interacting species, to parameterize to single-species occupancy models. We found that landscape composition at three different scales (500 and 1000 m buffer around camera locations, and 3 × 3 km grid cell) had little effect on species occurrence. We identified strong negative interspecific relations between carnivores, with bobcat occurrence being influenced by presence of coyotes, red fox occurrence by gray foxes, and raccoon occurrence by Virginia possums. While these findings cannot discriminate between habitat partitioning (spatial or temporal) and competition (direct or interference), they lend support to complex dynamics between invasive coyotes and red foxes and recovering (bobcat) and declining (gray fox) native carnivore species. In particular, the negative relation between the apex predator in our system, C. latrans, and L. rufus, raise further questions on whether direct competition from coyotes has the potential to slow bobcat population recovery. In the context of regulated trapping (ongoing for gray fox and potential season for bobcat), a better understanding of the carnivore intraguild relations can inform management and conservation actions targeted at minimizing the impact of competition on at-risk native species from non-native species.
Factors associated with co-occurrence of large carnivores in a human-dominated landscape
Biodiversity and Conservation
We investigated the factors facilitating co-occurrence of two large carnivores, tigers (Panthera tigris) and common leopards (Panthera pardus), within a human-dominated landscape. We estimated their density and population size using camera-trap photographs and examined spatial segregation of habitats, temporal activity pattern, and diets in Chitwan National Park, Nepal. A Bayesian spatially-explicit capture-recapture model estimated densities of 3.2-4.6 (3.94 ± 0.37) tigers and 2.6-4.1 (3.31 ± 0.4) leopards per 100 km 2 with abundance of 70-102 tigers and 66-105 leopards. Tigers occupied the prime habitats (grasslands and riverine forests) in alluvial floodplains of the Park whereas leopards appeared in Sal forests and marginal areas where livestock are present. Both tigers and leopards showed crepuscular activity patterns with a high overlap but tigers were less active during the day compared to leopards. Leopards' activity in the day increased in the presence of tigers. Tiger and leopard diet overlapped considerably (90%). Compared to leopards, tigers consumed a higher proportion of the large prey and a smaller proportion of livestock. Our study demonstrates that sympatric large carnivores can coexist in high densities in prey rich areas that contain a mosaics of habitats. To increase the resilience and size of the Chitwan carnivore population, strategies are needed to increase prey biomass and prevent livestock depredation in adjacent forests. Long-term monitoring is also required to obtain a detailed understanding of the interaction between the large carnivores and their effects on local communities living in forest fringes within the landscape.
Large predators limit herbivore densities in northern forest ecosystems
European Journal of Wildlife Research, 2012
There is a lack of scientific consensus about how top-down and bottom-up forces 10 interact to structure terrestrial ecosystems. This is especially true for systems with large 11 carnivore and herbivore species where the effects of predation versus food limitation on 12 herbivores are controversial. Uncertainty exists whether top-down forces driven by large 13 carnivores are common, and if so, how their influences vary with predator guild composition 14 and primary productivity. Based on data and information in 42 published studies from over a 15 50-year time span, we analyzed the composition of large predator guilds and prey densities 16 across a productivity gradient in boreal and temperate forests of North America and Eurasia. 17