Carnivore Community Structure In A Changing World

Download or read book Carnivore Community Structure in a Changing World written by Mauriel Rodriguez Curras and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carnivores are ecologically important members of communities and ecosystems because a relatively low number of individuals can cause both strong direct (consumptive) and indirect (non-consumptive) effects that structure the habitat use, distribution, and abundance of subordinate guild members, and ultimately shape the interactions of entire food webs. Understanding how species interactions cascade throughout carnivore guilds is important for predicting community-wide responses to the ongoing repatriation of the largest carnivores- either naturally or through human assistance - especially in the face of global change. Accordingly, a wholistic framework that integrates the negative effects from suppression (i.e., intraguild aggression) and the positive effects from facilitation (i.e., resource subsidies) will improve our understanding of community dynamics. The overarching goal of my dissertation is (i) to provide greater insights how suppression and facilitation structure carnivore communities across resource gradients, (ii) disentangle the mechanisms underlying meso- and small carnivore resource use, and (iii) develop novel testable and predictive models of carnivore community interactions following the repatriation of large carnivores to human landscapes.Each chapter of this dissertation is written and formatted for publication as a manuscript in a peer-reviewed journal. Chapter 1 (Rodriguez Curras et al. 2021, Behavioral Ecology) explicitly tests the behavioral mechanisms that drive carnivore community interactions. We used a combination of giving up density experiments and a novel modeling approach to test the impacts of habitat structure, behavior, and space use. We found that there was a dominance hierarchy from the apex carnivore through the meso-carnivore to the subordinate small carnivore, which was reflected in space. Although both meso- and small carnivores exhibited similar predator avoidance behavioral responses to apex carnivores, the habitat associations of apex carnivores only altered meso-carnivore space use. Our results broadly suggest that the bias in risk management we observed for meso-carnivores likely translates into a stable co-existence of this community of competing carnivores. In Chapter 2 (Rodriguez Curras et al. 2024, Frontiers in Ecology and the Environment), we took advantage of the wolf (Canis lupus) reintroduction to Isle Royale in 2018 to test the drivers of community structure. In a before-after study, we quantified the spatial, behavioral, trophic, and demographic effects that a large carnivore (wolves) reintroduction to Isle Royale National Park had on meso- (foxes; Vulpes vulpes) and small carnivores (martens; Martes americana). The reintroduction of wolves produced a phase-dependent pulse perturbation; wolves constrained the distribution of foxes benefiting martens, yet foxes altered their behavior, notably using human campsites and food more frequently, which buffered demographic consequences. Once wolf packs coalesced, all observed changes subsided, and competitive interactions returned to their pre-wolf values. Our results show that some predicted - and often desired - consequences of large carnivore reintroductions may not be permanent due to the transitory dynamics of social carnivores and the presence of humans, even within a "pristine wilderness". Chapter 3 (Rodriguez Curras et al. 2024, in Review at Oikos) explores the drivers of Eltonian niche conservatism in carnivore communities. Specifically, we found that trophic facilitation by wolves and resource subsidies from humans altered the foraging strategies of individual subordinate carnivores, resulting in disparate foraging strategies for foxes. Our results highlight that Eltonian niche conservatism in carnivore communities is driven by resource subsidies, both from the provisioning of carrion by large carnivores to meso-carnivores and from human foods subsidizing small carnivores. More broadly, our work suggests that large carnivore repatriation can restore some species interactions, while human resource subsidies can strongly decouple competitive interactions. Finally, Chapter 4 (Rodriguez Curras and Pauli, prepared for Conservation Letters or Biology Letters) explores a similar theme to Chapter 3 though in a seasonal context. Not surprisingly, seasonality strongly influenced meso-carnivore diet and we found strong support for yearly periodicity in their diet. Broadly, our results suggest that trophic facilitation from wolves and resource subsidies from humans are complementary and operate asynchronously throughout the year. The results from this chapter suggest that asynchronous dual subsidies from restored large carnivores during winter and human recreation during summer can lead to an increase to the overall nutritional landscape for plastic meso-carnivores, which can ultimately destabilize meso-carnivore populations and provides alternative means for 'the rise of the meso-predator'. My dissertation provides important insights into ecological and conservation issues of local and global importance - the impacts of humans to carnivore community interactions. Broadly, my research supports the expected consequences of restoring community interactions through the repatriation of large carnivores though highlights an underappreciated force in these community interactions: humans and human resource subsidies strongly mediating carnivore community interactions.