Facultative predation and scavenging by mammalian carnivores: seasonal, regional and intra-guild comparisons (original) (raw)
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Inter-specific interactions linking predation and scavenging in terrestrial vertebrate assemblages
Biological reviews of the Cambridge Philosophical Society, 2014
Predation and scavenging have been classically understood as independent processes, with predator-prey interactions and scavenger-carrion relationships occurring separately. However, the mere recognition that most predators also scavenge at variable rates, which has been traditionally ignored in food-web and community ecology, leads to a number of emergent interaction routes linking predation and scavenging. The general goal of this review is to draw attention to the main inter-specific interactions connecting predators (particularly, large mammalian carnivores), their live prey (mainly ungulates), vultures and carrion production in terrestrial assemblages of vertebrates. Overall, we report an intricate network of both direct (competition, facilitation) and indirect (hyperpredation, hypopredation) processes, and provide a conceptual framework for the future development of this promising topic in ecological, evolutionary and biodiversity conservation research. The classic view that scavenging does not affect the population dynamics of consumed organisms is questioned, as multiple indirect top-down effects emerge when considering carrion and its facultative consumption by predators as fundamental and dynamic components of food webs. Stimulating although challenging research opportunities arise from the study of the interactions among living and detrital or non-living resource pools in food webs.
The Role of Top Carnivores in Regulating Terrestrial Ecosystems
1999
Land managers often are responsible for the maintenance of species diversity and resilience. This requires knowledge of ecosystem dynamics over decades and centuries. Resource-driven (bottom-up) models have guided early thought on managing species and ecosystems. Under this paradigm, carnivores have little ecological value, and throughout the 20 th Century carnivore management strategies (often extirpation) have reflected that concept. An alternative hypothesis, however, states that herbivores reduce the biomass of plants, but in turn, the biomass of herbivores is checked by the presence of carnivores. As such, carnivores have great ecological value. Their predation activities create impacts that ripple downward through the trophic levels of an ecosystem. Here we discuss some potential pathways through which carnivores contribute to ecosystem processes and species diversity. The subtleties of these interactions have strong implications for management strategies of carnivores. Without considering these indirect impacts, short-sighted management strategies to reduce carnivores might cause extensive and long-term changes in ecosystem structure and function.
Carnivore carcasses are avoided by carnivores
The Journal of animal ecology, 2017
Ecologists have traditionally focused on herbivore carcasses as study models in scavenging research. However, some observations of scavengers avoiding feeding on carnivore carrion suggest that different types of carrion may lead to differential pressures. Untested assumptions about carrion produced at different trophic levels could therefore lead ecologists to overlook important evolutionary processes and their ecological consequences. Our general goal was to investigate the use of mammalian carnivore carrion by vertebrate scavengers. In particular, we aimed to test the hypothesis that carnivore carcasses are avoided by other carnivores, especially at the intraspecific level, most likely to reduce exposure to parasitism. We take a three-pronged approach to study this principle by: (i) providing data from field experiments, (ii) carrying out evolutionary simulations of carnivore scavenging strategies under risks of parasitic infection, and (iii) conducting a literature-review to test...
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.
Ecology, 2018
After centuries of declining abundance and distribution, apex carnivores are repatriating parts of their historical range across Europe, North America, South America, and Asia. These recoveries are not occurring only in remote wildlands, but are increasingly found in landscapes featuring a strong human presence. With their return to these landscapes, there is hope that many of the services carnivores provide will return too. Indeed, even at low densities, carnivores can regulate prey populations, induce trophic cascades that release plants from herbivory, control mesopredators, reduce and confine disease outbreaks, improve human health, control exotic species, enhance carbon storage and support a more diverse community of organisms. These are lofty expectations for this guild, some of which will be realized. Given that in many instances carnivore recolonization will be to strongly modified and even entirely novel landscapes, it is likely that the functional role of carnivores will be importantly altered, only partially realized, or in some cases, completely different. Nowhere will this altered role of carnivores be more evident than in their relationship with obligate scavengers.
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 carnivore impacts are context-dependent
Food Webs, 2017
Interactions between large carnivores and other species may be responsible for impacts that are disproportionately large relative to their density. Context-dependent interactions between species are common but often poorly described. Caution must be expressed in seeing apex predators as ecological saviours because ecosystem services may not universally apply, particularly if inhibited by anthropogenic activity. This review examines how the impacts of large carnivores are affected by four major contexts (species assemblage, environmental productivity, landscape, predation risk) and the potential for human interference to affect these contexts. Humans are the most dominant landscape and resource user on the planet and our management intervention affects species composition, resource availability, demography, behaviour and interspecific trophic dynamics. Humans can impact large carnivores in much the same way these apex predators impact mesopredators and prey species-through densitymediated (consumptive) and trait/behaviourally-mediated (non-consumptive) pathways. Mesopredator and large herbivore suppression or release, intraguild competition and predation pressure may all be affected by human context. The aim of restoring 'natural' systems is somewhat problematic and not always pragmatic. Interspecific interactions are