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1. Gifts of an enemy: scavenging dynamics in the presence of wolves ( Canis lupus )

   https://doi.org/10.1093/jmammal/gyab020  

   Klauder, Kaija J; Borg, Bridget L; Sivy, Kelly J; Prugh, Laura R (March 2021, Journal of Mammalogy)

   Hopkins, Jack (Ed.)

   Abstract Carrion represents an important resource for carnivores. Examining competition for carrion in a risk–reward framework allows for a better understanding of how predator guilds compete for and benefit from carrion. We used trail camera data to compare wintertime carrion use and vigilance behavior of four carnivores in Denali National Park and Preserve. We found that carrion use was dominated by wolves (Canis lupus) and wolverines (Gulo gulo), followed by red foxes (Vulpes vulpes) and coyotes (Canis latrans). Wolves and wolverines were twice as likely to visit a carcass as foxes and coyotes, and their visits were longer and more numerous. Our results suggest scavenging animals reduced their risk exposure primarily by reducing their use of carrion, with some evidence of increased vigilance at busy sites. We found that carrion use and behavior at carcass sites were influenced by the mortality type of the carcass, the age of the carcass, and the long-term intensity of wolf use in the area. Our results also suggest that wolves are the “top scavenger,” and indicate that intraguild competition for carrion strongly affects which species benefit from carrion, with larger and more aggressive species dominating. 

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2. Droughts reshape apex predator space use and intraguild overlap

   https://doi.org/10.1111/1365-2656.14192  

   West, Leigh; Rafiq, Kasim; Converse, Sarah J; Wilson, Alan M; Jordan, Neil R; Golabek, Krystyna A; McNutt, J Weldon; Abrahms, Briana (November 2024, Journal of Animal Ecology)

   Abstract Droughts are increasing in frequency and severity globally due to climate change, leading to changes in resource availability that may have cascading effects on animal ecology. Resource availability is a key driver of animal space use, which in turn influences interspecific interactions like intraguild competition. Understanding how climate‐induced changes in resource availability influence animal space use, and how species‐specific responses scale up to affect intraguild dynamics, is necessary for predicting broader community‐level responses to climatic changes.Although several studies have demonstrated the ecological impacts of drought, the behavioural responses of individuals that scale up to these broader‐scale effects are not well known, particularly among animals in top trophic levels like large carnivores. Furthermore, we currently lack understanding of how the impacts of climate variability on individual carnivore behaviour are linked to intraguild dynamics, in part because multi‐species datasets collected at timescales relevant to climatic changes are rare.Using 11 years of GPS data from four sympatric large carnivore species in southern Africa—lions (Panthera leo), leopards (Panthera pardus), African wild dogs (Lycaon pictus) and cheetahs (Acinonyx jubatus)—spanning 4 severe drought events, we test whether drought conditions impact (1) large carnivore space use, (2) broad‐scale intraguild spatial overlap and (3) fine‐scale intraguild interactions.Drought conditions expanded space use across species, with carnivores increasing their monthly home range sizes by 35% (wild dogs) to 66% (leopards). Drought conditions increased the amount of spatial overlap between lions and subordinate felids (cheetahs and leopards) by up to 119%, but only lion‐cheetah encounter rates were affected by these changes, declining in response to drought.Our findings reveal that drought has a clear signature on the space use of multiple sympatric large carnivore species, which can alter spatiotemporal partitioning between competing species. Our study thereby illuminates the links between environmental change, animal behaviour and intraguild dynamics. While fine‐scale avoidance strategies may facilitate intraguild coexistence during periodic droughts, large carnivore conservation may require considerable expansion of protected areas or revised human‐carnivore coexistence strategies to accommodate the likely long‐term increased space demands of large carnivores under projected increases in drought intensity. 

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3. Parasitoid avoidance of intraguild predation drives enemy complementarity in a multi‐trophic ecological network

   https://doi.org/10.1002/ecy.4483  

   Hennessy, Andrew B; Anderson, Riley M; Mitchell, Nora; Mooney, Kailen A; Singer, Michael S (January 2025, Ecology)

   Abstract How consumer diversity determines consumption efficiency is a central issue in ecology. In the context of predation and biological control, this relationship concerns predator diversity and predation efficiency. Reduced predation efficiency can result from different predator taxa eating each other in addition to their common prey (interference due to intraguild predation). By contrast, multiple predator taxa with overlapping but complementary feeding niches can generate increased predation efficiency on their common prey (enemy complementarity). When viewed strictly from an ecological perspective, intraguild predation and enemy complementarity are opposing forces. However, from an evolutionary ecology perspective, predators facing strong intraguild predation may evolve traits that reduce their predation risk, possibly leading to niche complementarity between enemies; thus, selection from intraguild predation may lead to enemy complementarity rather than opposing it. As specialized predators that live in or on their hosts, parasitoids are subjected to intraguild predation from generalist predators that consume the parasitoids' hosts. The degree to which parasitoid–predator interactions are ruled by interference versus enemy complementarity has been debated. Here, we address this issue with field experiments in a forest community consisting of multiple species of trees, herbivorous caterpillars, parasitoids, ants, and birds. Our experiments and analyses found no interference effects, but revealed clear evidence for complementarity between parasitoids and birds (not ants). Parasitism rates by hymenopterans and dipterans were negatively associated with bird predation risk, and the variation in the strength of this negative association suggests that this enemy complementarity was due to parasitoid avoidance of intraguild predation. We further argue that avoidance of intraguild predation by parasitoids and other arthropod predators may explain enigmatic patterns in vertebrate–arthropod–plant food webs in a variety of terrestrial ecosystems. 

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4. Complex interactions with nutrients and sediment alter the effects of predation on a reef‐building coral

   https://doi.org/10.1111/maec.12670  

   Rice, Mallory M.; Baldwin, Daniel G.; Fischer, Janine N.; Fuchs, Corinne; Burkepile, Deron E. (June 2021, Marine Ecology)

   Abstract Framework‐building corals create the three‐dimensional structure of coral reefs and are subject to predation from fishes, echinoderms, and gastropods. Anthropogenic stressors can magnify the effects of such top‐down pressure on foundation species. The gastropodCoralliophilaviolacea(Kiener, 1836) depletes coral energy reserves via predation, potentially increasing coral susceptibility to land‐based pollution (i.e., sediment accumulation and nutrient pollution). We hypothesized that sedimentation would worsen coral mortality, while nutrient enrichment would mitigate the harmful effects of sediment and predation on coral mortality by increasing the densities of algal symbionts. To test these hypotheses, we conducted in situ surveys of the fringing reefs in Mo'orea, French Polynesia to explore the relationships among massivePoritesspp. cover,C. violaceadensities, and sediment accumulation on coral colonies across low and high nutrient sites. We also conducted a factorial field experiment to test the interactions among these stressors on coral tissue mortality, symbiont densities, and chlorophyll. MassivePoritescolonies at higher nutrient sites hadC. violaceadensities 13 times higher than at low nutrient sites but there was no difference in the amount of live tissue on coral colonies with or without snails among these sites. In our experiment, there were interactions between predation and nutrients as well as nutrients and sediment that impacted coral mortality. Sedimentation and predation byC. violaceaincreased coral tissue mortality independently by ~20%. Nutrient enrichment reduced this effect in corals under sedimentation or predation pressure by lowering coral tissue mortality by 18% and increasing algal symbiont densities by ~28%. Our results indicate that sediment does not magnify top‐down pressure on this coral, and that moderate nutrient enrichment may interact with predation in complex, unexpected ways to alter the responses of corals to top‐down pressure. 

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5. Habitat traits and predation interact to drive abundance and body size patterns in associated fauna

   https://doi.org/10.1002/ece3.10771  

   Stelling‐Wood, Talia P.; Poore, Alistair G.; Hughes, A. Randall; Everett, Jason D.; Gribben, Paul E. (December 2023, Ecology and Evolution)

   Abstract Habitat‐forming organisms provide three‐dimensional structure that supports abundant and diverse communities. Variation in the morphological traits of habitat formers will therefore likely influence how they facilitate associated communities, either via food and habitat provisioning, or by altering predator–prey interactions. These mechanisms, however, are typically studied in isolation, and thus, we know little of how they interact to affect associated communities. In response to this, we used naturally occurring morphological variability in the algaSargassum vestitumto create habitat units of distinct morphotypes to test whether variation in the morphological traits (frond size and thallus size) ofS. vestitumor the interaction between these traits affects their value as habitat for associated communities in the presence and absence of predation. We found morphological traits did not interact, instead having independent effects on epifauna that were negligible in the absence of predation. However, when predators were present, habitat units with large fronds were found to host significantly lower epifaunal abundances than other morphotypes, suggesting that large frond alga provided low‐value refuge from predators. The presence of predators also influenced the size structure of epifaunal communities from habitat units of differing frond size, suggesting that the refuge value ofS. vestitumwas also related to epifauna body size. This suggests that habitat formers may chiefly structure associated communities by mediating size‐selective predation, and not through habitat provisioning. Furthermore, these results also highlight that habitat traits cannot be considered in isolation, for their interaction with biotic processes can have significant implications for associated communities. 

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