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- All Subjects: Urban Ecology
- Creators: Deviche, Pierre
Description
Understanding the drivers of diet selection by carnivores is key for wildlife conservation and management, particularly in the Anthropocene. Yet, most assessments of predation do not consider how spatio-temporal prey availability or nutrition influence carnivore diet selection. Using a novel data integration approach for camera trap and scat data, I assessed how spatial and temporal components of prey availability influenced diet selection by bobcats (Lynx rufus) in Colorado, USA (Chapter 1) and coyotes (Canis latrans) in Arizona, USA (Chapter 2) in areas of low and moderate levels of urbanization. I also assessed coyote diets using the nutritional geometric framework to determine coyote macronutrient consumption seasonally and relative to urbanization (Chapter 3). My results suggest that cottontail rabbit availability largely drove bobcat predation, and that bobcats consumed prey relative to its availability overall and in wildland areas, but that this relationship weakened in anthropogenic regions. I also found that, overall, models of prey availability that incorporated the temporal overlap between predator and prey taxa predicted bobcat diet selection better than models assessing the spatial availability of prey. Similarly, I found coyotes consumed prey relative to its availability overall and in sites with lower levels of human influence across seasons, but not in moderately urbanized sites. I also found that models of prey availability that incorporated time better predicted coyote diets compared to models assessing the spatial availability of prey. Finally, I observed that the macronutrient composition of coyote diets was similar between moderately and less urbanized sites, particularly in the spring-summer season. However, coyote macronutrient consumption differed seasonally, with coyotes eating more non-protein energy relative to protein energy when carbohydrate-rich mesquite (Prosopis spp.) was more available in the fall-winter. In addition, the consistently high consumption of lipid-rich domestic cats in moderately urbanized sites further supports the hypothesis that coyotes increased their consumption of non-protein energy when available and when assuming protein needs were already met. This dissertation provides new insights into how urbanized landscapes impact carnivore ecology. Since diet selection drives many human-carnivore conflicts, this research can also be used to help inform wildlife management and decision-making in anthropogenic areas.
ContributorsWeiss, Katherine (Author) / Sterner, Beckett (Thesis advisor) / Schipper, Jan (Thesis advisor) / Deviche, Pierre (Committee member) / Lewis, Jesse S (Committee member) / Strauss, Eric G (Committee member) / Arizona State University (Publisher)
Created2024
Description
Human-inhabited or -disturbed areas pose many unique challenges for wildlife, including increased human exposure, novel challenges, such as finding food or nesting sites in novel structures, anthropogenic noises, and novel predators. Animals inhabiting these environments must adapt to such changes by learning to exploit new resources and avoid danger. To my knowledge no study has comprehensively assessed behavioral reactions of urban and rural populations to numerous novel environmental stimuli. I tested behavioral responses of urban, suburban, and rural house finches (Haemorhous mexicanus) to novel stimuli (e.g. objects, noises, food), to presentation of a native predator model (Accipiter striatus) and a human, and to two problem-solving challenges (escaping confinement and food-finding). Although I found few population-level differences in behavioral responses to novel objects, environment, and food, I found compelling differences in how finches from different sites responded to novel noise. When played a novel sound (whale call or ship horn), urban and suburban house finches approached their food source more quickly and spent more time on it than rural birds, and urban and suburban birds were more active during the whale-noise presentation. In addition, while there were no differences in response to the native predator, rural birds showed higher levels of stress behaviors when presented with a human. When I replicated this study in juveniles, I found that exposure to humans during development more accurately predicted behavioral differences than capture site. Finally, I found that urban birds were better at solving an escape problem, whereas rural birds were better at solving a food-finding challenge. These results indicate that not all anthropogenic changes affect animal populations equally and that determining the aversive natural-history conditions and challenges of taxa may help urban ecologists better understand the direction and degree to which animals respond to human-induced rapid environmental alterations.
ContributorsWeaver, Melinda (Author) / McGraw, Kevin J. (Thesis advisor) / Rutowski, Ronald (Committee member) / Pratt, Stephen (Committee member) / Bateman, Heather (Committee member) / Deviche, Pierre (Committee member) / Arizona State University (Publisher)
Created2018
Description
For animals that experience annual cycles of gonad development, the seasonal timing (phenology) of gonad growth is a major adaptation to local environmental conditions. To optimally time seasonal gonad growth, animals use environmental cues that forecast future conditions. The availability of food is one such environmental cue. Although the importance of food availability has been appreciated for decades, the physiological mechanisms underlying the modulation of seasonal gonad growth by this environmental factor remain poorly understood.
Urbanization is characterized by profound environmental changes, and urban animals must adjust to an environment vastly different from that of their non-urban conspecifics. Evidence suggests that birds adjust to urban areas by advancing the timing of seasonal breeding and gonad development, compared to their non-urban conspecifics. A leading hypothesis to account for this phenomenon is that food availability is elevated in urban areas, which improves the energetic status of urban birds and enables them to initiate gonad development earlier than their non-urban conspecifics. However, this hypothesis remains largely untested.
My dissertation dovetailed comparative studies and experimental approaches conducted in field and captive settings to examine the physiological mechanisms by which food availability modulates gonad growth and to investigate whether elevated food availability in urban areas advances the phenology of gonad growth in urban birds. My captive study demonstrated that energetic status modulates reproductive hormone secretion, but not gonad growth. By contrast, free-ranging urban and non-urban birds did not differ in energetic status or plasma levels of reproductive hormones either in years in which urban birds had advanced phenology of gonad growth or in a year that had no habitat-related disparity in seasonal gonad growth. Therefore, my dissertation provides no support for the hypothesis that urban birds begin seasonal gonad growth because they are in better energetic status and increase the secretion of reproductive hormones earlier than non-urban birds. My studies do suggest, however, that the phenology of key food items and the endocrine responsiveness of the reproductive system may contribute to habitat-related disparities in the phenology of gonad growth.
Urbanization is characterized by profound environmental changes, and urban animals must adjust to an environment vastly different from that of their non-urban conspecifics. Evidence suggests that birds adjust to urban areas by advancing the timing of seasonal breeding and gonad development, compared to their non-urban conspecifics. A leading hypothesis to account for this phenomenon is that food availability is elevated in urban areas, which improves the energetic status of urban birds and enables them to initiate gonad development earlier than their non-urban conspecifics. However, this hypothesis remains largely untested.
My dissertation dovetailed comparative studies and experimental approaches conducted in field and captive settings to examine the physiological mechanisms by which food availability modulates gonad growth and to investigate whether elevated food availability in urban areas advances the phenology of gonad growth in urban birds. My captive study demonstrated that energetic status modulates reproductive hormone secretion, but not gonad growth. By contrast, free-ranging urban and non-urban birds did not differ in energetic status or plasma levels of reproductive hormones either in years in which urban birds had advanced phenology of gonad growth or in a year that had no habitat-related disparity in seasonal gonad growth. Therefore, my dissertation provides no support for the hypothesis that urban birds begin seasonal gonad growth because they are in better energetic status and increase the secretion of reproductive hormones earlier than non-urban birds. My studies do suggest, however, that the phenology of key food items and the endocrine responsiveness of the reproductive system may contribute to habitat-related disparities in the phenology of gonad growth.
ContributorsDavies, Scott (Author) / Deviche, Pierre (Thesis advisor) / Sweazea, Karen (Committee member) / McGraw, Kevin (Committee member) / Orchinik, Miles (Committee member) / Warren, Paige (Committee member) / Arizona State University (Publisher)
Created2014