1,721,023 research outputs found
Large Carnivore Behavior and Intraguild Interactions Under Anthropogenic Influence
No full textThesis (Ph.D.)--University of Washington, 2023Among the many human activities that affect wildlife, urbanization is one of the most prominent sources of species extinction and biodiversity loss. Responses to urbanization vary across taxa, with large carnivores being particularly sensitive to this process owing to their space needs and energy requirements. Not surprisingly, therefore, large carnivore declines in the face of urbanization are well documented but changes to the behavior and ecology of species that are able to persist in built environments have received less attention. In the state of Washington, sympatric cougar (Puma concolor) and American black bear (Ursus americanus) populations overlap with wildland and residential landscapes, providing a rare opportunity to evaluate the behavioral responses of multiple large carnivores to urbanization. Accordingly, this dissertation examines how various forms of anthropogenic disturbance linked with urbanization impact large carnivore behavior and interspecific interactions, with the broader goal of improving our understanding of the mechanisms driving changes to the ecology of large predators as they must increasingly navigate a human-dominated world. In Chapter 1, I provide justification for large carnivore research in urban environments. In Chapter 2, I explore changes to individual and population niche breadth in black bears as a function of residential development. I demonstrate using resource utilization functions (RUFs) that bear population-level use increased significantly as distance to residential mature forest, lakes, and rivers decreased. Black bears exhibited high individual variation in both residential and wildland landscapes. Nevertheless, black bear use near mature forest differed significantly between residential and wildland landscapes as bears began to enter hyperphagia and use near residential mature forest and residential rivers differed between females and males in summer. In Chapter 3, I once again employ RUFs to evaluate resource use by black bears navigating managed forests in western Washington with (Snoqualmie Forest) and without (Department of Natural Resources lands) diversionary feeding during fed and non-fed portions of the year to shed light on large carnivore responses to human subsidies in areas just beyond the urban fringe. Black bear use of young forest stands (15-30 years), as well as other landscape attributes, was similar between managed forests with and without feeding stations irrespective of whether supplemental food was supplied. Notably, individual variation was significant for nearly every covariate in both forests, with bears often demonstrating contrasting patterns of use, effectively washing out any population-level effects of diversionary feeding and harvest intensity on resource use. In Chapter 4, I explore whether residential development in the form of housing density (residences/ha), along with demographic and environmental covariates, impact the propensity for black bears to scavenge cougar-killed prey along western Washington’s wildland-urban gradient. The summer season and housing density were significant negative predictors of black bear scavenging, and cougar handling time was a significant positive predictor of bear carcass visitation. Overall, my results reveal that residential development can modify population-wide black bear behavior in ways that may shape patterns of human-wildlife interaction even though individual bear responses to anthropogenic disturbance often vary. My results also suggest that the impact of urbanization on interspecific relationships among large carnivores can be dramatic, as even modest levels of residential development all but eliminated black bear scavenging on cougar kills. This dissertation provides novel insights into predator-predator interactions in residential landscapes and advances our understanding of the myriad ways residential development may disrupt interactions within carnivore guilds, creating avenues of further study into the mechanisms structuring urban wildlife communities
Impacts of Re-colonizing Gray Wolves on Mule Deer and White-tailed Deer in North-Central Washington
No full textThesis (Ph.D.)--University of Washington, 2018Previous research on gray wolves (Canis lupus) in protected landscapes demonstrates these large carnivores can have consumptive and non-consumptive effects on prey species which lead to top-down trophic cascades. However, much remains to be known about impacts of gray wolves on prey in managed landscapes as well as how these predators influence interactions between prey species. Recent natural re-colonization of gray wolves to managed landscapes of Washington state facilitated a natural experiment wherein we explored impacts of gray wolves on multiple sympatric prey species – mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus). We compared survival, habitat use, and resource partitioning of adult mule deer and adult white-tailed deer in wolf present and wolf absent areas. Mule deer and white-tailed deer survival rates were not negatively impacted by presence of gray wolves. Season was the primary factor in explaining all predator and human-caused mortality. Our data suggests gray wolves may not have consumptive effects on native prey populations in Washington state. Next, mule deer and white-tailed deer experiencing gray wolf predation risk did exhibit shifts in habitat use relative to conspecifics in areas without gray wolves. Shifts in habitat use by mule deer and white-tailed occurred at coarse and fine-spatial scales, respectively, and were explained by divergent escape tactics of each prey species and the landscape features that promote escape of each deer species when facing gray wolf predation risk. It appears gray wolves can influence habitat use of multiple prey species and potentially at differing spatial scales depending on escape behavior of prey species and the landscape features that promote escape of prey from predation. Our results suggest gray wolves could initiate multiple top-down trophic cascades via prey species specific shifts in habitat use in response to gray wolf predation risk. Lastly, there was increased resource partitioning between mule deer and white-tailed deer in areas with gray wolves compared to resource partitioning between mule deer and white-tailed deer in areas without gray wolves. Increased resource partitioning between mule deer and white-tailed deer was again explained by divergent escape tactics of each prey species and the landscape features promoting escape of each deer species subject to wolf predation risk. However, direction and magnitude of resource partitioning between mule deer and white-tailed in areas with gray wolves compared to areas without gray wolves varied with season and scale. Our findings demonstrate that gray wolf predation risk can mediate interactions between co-occurring prey species but is context-dependent. We suggest further research on consumptive and non-consumptive effects of gray wolves on multiple prey species to better understand the potential for top-down trophic cascades in managed landscapes
Using non-invasive techniques to examine black bear (Ursus americanus) abundance in the North Cascades Ecosystem, Washington State
No full textThesis (Master's)--University of Washington, 2013Recent advances in non-invasive research methods have facilitated less costly evaluations of bear populations across wide geographic ranges. Non-invasive hair-snagging and genetic tagging allow identification of species, sex, and individual bears without necessitating direct capture or observation. From 2008 to 2011 a large, multi-agency project deployed barbed wire hair-snag corrals to collect DNA samples from black bears (Ursus americanus) in the North Cascades Ecosystem (NCE) of Washington State. Using the genetic and detection data, I examined the influence of human activities and habitat characteristics on bear abundance across heterogenous landscapes of the NCE. Bear abundance was positively associated with the proportion of the landscape in shrubfields, open mesic forests, and dry forests with moderate overstory tree canopy closure. A positive northward trend in abundance existed, but was strongest for female bears. Male abundance was higher on national park lands and did not differ between roaded, frontcountry areas and designated wilderness after accounting for habitat variation. This finding suggests that roadless wilderness areas are not acting as source areas or refugia for bears from human activities. No other research to date in Washington State has examined the influence of habitat and anthropogenic variables on black bears across such a large geographic expanse, and the results of my study should help guide management of black bear populations in the NCE. Effective and science-based management of black bears is especially important given the challenge of maintaining viable populations of long-lived species with relatively low fecundity
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Predator species identification from saliva at kill sites with limited remains
Get PDFThesis (Master's)--University of Washington, 2016-06Kill site investigations can provide valuable data about elusive predator species and predator-prey interactions for wildlife scientists and managers alike. However, the predator species must be definitively identified as the one responsible for the predation event. The traditional method of visually analyzing prey remains to identify predator species is prone to observer bias and may be particularly challenging in systems with congeneric predators. Often, so few remains are left behind that visual analysis is rendered impossible. Other potential evidence left by predators, such as scat or tracks, may be difficult to reliably link to the responsible predator or require adequate substrate conditions. Continuing advancements in molecular techniques provide a more objective option that is also feasible on limited remains: swabbing for predator DNA from saliva. This underutilized method has primarily been applied to larger carcasses that provide ample surface area to collect epithelial saliva cells. This study demonstrates the usefulness of a saliva-swabbing method for smaller prey with minimal surface area, including kill sites with almost no prey remains or even just a radio-collar left behind. This is also the first study to compare saliva-swabbing success by sample type (carcass remains versus the radio-collar). From 2010-2013, I employed forensic techniques to increase certainty about predator species identification at snowshoe hare (Lepus americanus) kill sites for the ultimate purpose of elucidating predator-prey interactions. Predator saliva at kill sites was sampled with foam buccal swabs, stored in lysis buffer for shelf-stable preservation, and tested for predator mitochondrial DNA using the polymerase chain reaction (PCR) and species-specific primers. This saliva-swabbing method yielded definitive and objective predator species identification for the majority (58.5%) of sampled kill sites (N = 31/53). Not only were small amounts of remains (carcass and/or fur) often able to yield DNA from predator saliva, but saliva swabs from radio-collars proved to be significantly more successful for predator species identification (4.04 odds ratio). Saliva-swabbing also provided identifications at 65.5% of kill sites lacking unambiguous predator sign and contributed significantly more predator identifications throughout the year when compared to tracking methods. The expansion of saliva-swabbing methods to smaller prey, radio-collars, and limited remains allows for more definitive predator identifications at kill sites than have been possible with commonly employed methods, thus augmenting the potential to understand and manage for predators and pre
Carnivore responses to urbanization and human presence along an urban-wildland gradient in western Washington
No full textThesis (Master's)--University of Washington, 2022Urbanization and human activity are primary drivers of wildlife habitat loss and degradation, but few studies to date have explored their impacts simultaneously. I investigated how anthropogenic infrastructure and the presence of humans affected habitat use of six carnivore species along an urban-wildland gradient of human development in western Washington, USA. Specifically, I deployed camera traps at 175 locations to quantify habitat use by American black bears (Ursus americanus), bobcats (Lynx rufus), cougars (Puma concolor), coyotes (Canis latrans), Virginia opossums (Didelphis virginiana), and raccoons (Procyon lotor). I then used single-species, single-season occupancy models to characterize their respective patterns of habitat use. No covariate was significant for all six species, and I only detected significant relationships with any of the covariates for four of the species. Two species had significant relationships with distance to road but different responses; cougar occupancy increased while coyote occupancy probability decreased as the distance to road increased. Black bear occupancy was positively associated with increasing canopy cover and the probability of occupancy for opossums decreased withincreasing elevation. Cougars were not detected at any sites ≤ 250 m from any buildings, suggesting that cougars may avoid using habitat in close proximity to these structures. I detected no significant response to the presence of humans by any of the species. My results reveal that carnivore spatial responses to human infrastructure and presence are species-specific and can be limited, highlighting the need for efforts to identify key drivers of species differences as well as tailored conservation and management approaches
The Water Monitor Lizard Varanus salvator: Behavior, Ecology, and Human Dimensions in Banten, Indonesia
Get PDFThesis (Ph.D.)--University of Washington, 2015The water monitor lizard, Varanus salvator, is a large, ecologically flexible species commonly found in areas of human disturbance throughout its Southeast Asian range. The presence of anthropogenic resource subsidies may influence V. salvator behavior in such areas, potentially altering the social structure, ranging activity, and space use of this species. Overlapping human and V. salvator activity areas also create the potential for increased human-V. salvator conflict. We used behavioral observations and radio-telemetry to study V. salvator in an area of regular anthropogenic subsidy in Banten, Indonesia. We also conducted interviews with area residents to document local knowledge and to identify concerns regarding local herpetofauna. On Tinjil Island, Indonesia, we observed a higher incidence of intraspecific encounters among V. salvator in a human-subsidized area than in areas where animals foraged naturally. A greater number of agonistic interactions was also observed in the presence of food when compared to those in the absence of food. Our data suggest that on Tinjil Island a dominance hierarchy exists among V. salvator frequenting the area of anthropogenic subsidy. In addition, V. salvator activity areas appeared smaller in the dry season than in the wet season, when the island’s natural water and prey resources were more abundant. Similarly, V. salvator on the island showed increased use away from areas of anthropogenic subsidy in the wet season only. Through the interview process we learned that a local taboo prohibits the collection of V. salvator and Python reticulatus on Tinjil Island, but that the taboo is not observed in the nearby mainland villages, Muara Dua and Cisiih. In the villages, V. salvator is mainly considered a pest, but the meat of this species is also consumed for medicinal purposes. In our study V. salvator behavior in human-subsidized areas differed from that observed in wildland areas but varied temporally, indicating that anthropogenic subsidies may be more important for this population in the dry season when natural resources are less available. A location-specific taboo, official regulations, and anthropogenic subsidy serve to protect and maintain Tinjil Island’s V. salvator population. However, in nearby Muara Dua and Cisiih, local use for medicinal purposes and concerns over livestock depredation could lead to increased harvest and persecution of this species
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Predator-Prey Spatiotemporal Interactions in a Multi-Use Landscape
No full textThesis (Ph.D.)--University of Washington, 2020Apex predators can influence ecosystems by changing the density and behavior of herbivores and other predators. As an ecosystem superpredator, humans may also shape top-down effects in ecological communities by altering apex predator abundance and behavior. In many parts of the world, apex predators live in, or are returning to, landscapes that are human dominated. Thus, it is important to understand the ecological role of apex predators in anthropogenic, multi-use landscapes. I used motion-activated camera traps set in a multi-use landscape in northeastern Washington to compare the effects of: 1) wolves (Canis lupus) on spatiotemporal activity patterns of mesopredators and sympatric apex predators; and 2) the effects of hunting and apex predators on the spatiotemporal activity of herbivorous prey. In areas with wolves, other predators used temporal niche partitioning to avoid wolves. Cougars (Puma concolor) and coyotes (Canis latrans) became more active during the daytime, when wolves were least active, which significantly increased their activity overlap with humans. By contrast, bobcats (Lynx rufus) exposed to wolves changed their activity in patterns opposite to coyotes at nighttime and dusk. Although both mule deer (Odocoileus hemionus) and white-tailed deer (Odocoileus virginianus) increased nocturnality significantly during hunting seasons, the deer species showed species-specific spatiotemporal responses to hunting that, in the case of mule deer, deviated from their typical anti-predator behavior. This pushed mule deer, but not white-tailed deer, into greater spatiotemporal overlap with wolves during hunting seasons, and thus may lead to additive mortality on mule deer from increased wolf predation. In conclusion, the top-down effects of wolves on the behavior of their intraguild competitors appear to be resilient to human disturbance in this system. However, effects on their herbivore prey may be overwhelmed by humans during hunting seasons, leading to greater spatiotemporal overlap with predators. More broadly, my findings highlight that temporal behavioral plasticity is an underappreciated aspect of animal behavior that helps animals manage risk and reduce the negative effects of competition. In addition, the top-down effects of apex predators appear to persist in human-dominated landscapes, particularly within the carnivore guild
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