Wildlife management
Assessing the drivers of white-tailed deer (Odocoileus virginianus) migration: Exploring changing predation risk and food availability in an Ontario population
Animal migration is defined as the seasonal movement from one independent and non-overlapping range to another. Understanding how and why animals migrate is important not only to understand their life history processes but also for informing other important ecological processes such as the spread of wildlife disease and habitat alteration. Animal migrations have been impacted by human activity with instances of complete loss of migrations in human-altered areas. Understanding the drivers of migration can help predict responses to future environmental changes and potentially help conserve these phenomena. Seasonal movements of white-tailed deer (deer; Odocoileus virginianus; Zimmerman, 1780) have been linked to seasonal changes in environmental conditions that impact their ability to find food resources and risk of predation. The human shield hypothesis posits that prey species will select habitat close to people to use predator fear of humans to protect themselves from predation. Using global positioning system (GPS) collars, we examined the onset of deer migrations and assessed how environmental variables including snow, temperature, and plant biomass influenced migration departure dates using time-to-event models. We compared deer locations to data from GPS collared coyotes (Canis latrans; Say, 1823) within the same study area to explore daily space-use differences and examine if deer migrations were food or predation-risk driven using generalized linear mixed effects regression models. We found substantial annual and individual variation in deer migration dates. Snow depth was the strongest and most consistent predictor of deer migration, with individuals departing earlier with greater snow depth. Our regression analyses showed that deer selected for habitats closer to and with greater density of anthropogenic structures than coyotes at all times. After removing the animal locations close to areas with active supplemental feeding, these effects were diminished showing no differences in proximity or density of structures. Overall, we found more support for a food driven migration rather than a predator driven human shield. With the reduction in natural food caused by snow cover, we suggest that supplemental feeding is likely influencing the use of wintering areas by deer. The high proportion of deer migrating to human developed areas with supplemental feeders highlights the need for continued research into the impacts of human activity on animal behaviour.
Author Keywords: coyote, human shield, migration, supplemental feeding, white-tailed deer
Impacts of invasive hybrid cattail Typha x glauca and reduced marsh interspersion on muskrats (Ondatra zibethicus) in North America
Muskrat populations are declining across North America. In recent decades, hybrid cattail Typha x glauca has been invading wetlands in North America. This invasion is degrading wetland habitat, leading to reduced interspersion of water and vegetation. Muskrats are wetland-obligates and their populations are positively linked to marsh interspersion. Therefore, muskrat populations may be declining due to the invasion of T. x glauca and subsequent reduction in interspersion. To test this hypothesis, I first sampled marshes across south-central Ontario, comparing muskrat densities with the relative frequency of T. x glauca and the degree of interspersion. Second, I measured intensity of use by muskrats in a large wetland along a gradient of interspersion. My findings suggest that reduced interspersion may be contributing to muskrat population declines, but it is unclear to what degree T. x glauca is responsible. Further research is needed to understand the effects of wetland invasions on muskrat populations.
Author Keywords: invasive species, Ondatra zibethicus, Southern Ontario, Typha x glauca, wetlands, wildlife conservation
Remote Camera-traps as a Management Tool: Estimating Abundance and Landscape Effects on the Density of White-tailed Deer
Quantifying the impacts of environmental conditions on the abundance of wildlife populations is important for making informed management decisions in the face of increasing environmental threats. Managers require robust tools to estimate abundance and density of wildlife rapidly and with precision. Within the context of studying white-tailed deer, I evaluated the use of camera-traps and a recently developed spatial-mark resight model to estimate deer density and evaluate habitat and land use factors influencing deer density. The study was conducted in central Ontario, Canada on approximately 16 km2 of public land including the protected Peterborough Crown Game Preserve. Telemetry locations from 39 radio-collared deer were used and one hundred camera-traps were deployed for a total of 140 days from January 2022 to May 2022. Using telemetry locations and camera-trap photos I built a two-step spatial-mark resight model to estimate deer density. Deer density varied during the study as a portion of the population migrated to wintering areas outside of the study area. Despite fluctuations in precision, estimates improved towards the end of the study as more data became available and deer space use stabilized. The average deer density during the entire study was 3.0 deer/km2 (95% CI= 0.1, 5.8; SD= 1.7; CV= 55%; N= 238 deer). The lowest mean density was 0.2 deer/km2 (95% CI= 0.1, 0.4; SD= 0.1; CV= 50%; N= 15 deer) from February 26th to March 11th and the highest mean density was 4.8 deer/km2 (95% CI= 3.1, 6.2; SD= 0.8; CV= 17%; N= 378 deer) from May 7th to May 20th. When I incorporated spatial covariates into the model to estimate effects on deer density, higher proportions of mixed forest, deciduous forest, and road and trail density all had negative effects on deer density. While models contained some uncertainty, deer density appeared higher in the portion of the study area protected from licensed hunting. This thesis provides a framework for managers to use camera-traps and the spatial-mark resight model to monitor deer populations and link environmental covariates to spatial variation in density. As environmental threats such as habitat loss and infectious diseases increase in severity, monitoring wildlife population numbers will be vital for informed responses to these threats. The two-step spatial-mark resight model with environmental covariates provides managers with a long-term monitoring tool to evaluate management efforts and population health in forested areas.
Author Keywords: camera-trap, chronic wasting disease, landscape ecology, spatial-capture recapture, white-tailed deer, wildlife management
Linking large scale monitoring and spatially explicit capture–recapture models to identify factors shaping large carnivore densities: case study of the American black bear in Ontario, Canada
Understanding the spatial ecology of large carnivores in increasingly complex, multi-use landscapes is critical for effective conservation and management. Complementary to this need are robust monitoring and statistical techniques to understand the effect of bottom-up and top-down processes on wildlife population densities. However, for wide-ranging species, such knowledge is often hindered by difficulties in conducting studies over large spatial extents to fully capture the range of processes influencing populations. This thesis addresses research gaps in the above themes in the context of the American black bear (Ursus americanus) in the multi-use landscape of Ontario, Canada. First, I assess the performance of a widely adopted statistical modelling technique – spatially explicit capture-recapture (SECR) – for estimating densities of large carnivores (Chapter 2). Using simulations, I demonstrate that while SECR models are generally robust to unmodeled spatial and sex-based variation in populations, ignoring high levels of this variation can lead to bias with consequences for management and conservation. In Chapter 3, I investigate fine-scale drivers of black bear population density within study areas and forest regions by applying SECR models to a large-scale, multi-year black bear spatial capture-recapture dataset. To identify more generalizable patterns, in Chapter 4 I then assess patterns of black bear density across the province and within forest regions as a function of coarse landscape-level factors using the same datasets and assess the trade-offs between three different modeling techniques. Environmental variables were important drivers of black bear density across the province, while anthropogenic variables were more important in structuring finer-scale space use within study areas. Within forest regions these variables acted as both bottom-up and top-down processes that were consistent with ecological influences on black bear foods and intensity of human influences on the species' avoidance of developed habitats. Collectively, this thesis highlights the opportunities and challenges of working across multiple scales and over expansive landscapes within a SECR framework. Specifically, the multi-scale approach of this thesis allows for robust inference of the mechanisms structuring fine and broad scale patterns in black bear densities and offers insight to the relative influence of top-down and bottom-up forces in driving these patterns. Taken together, this thesis provides an approach for monitoring large carnivore population dynamics that can be leveraged for the species conservation and management in increasingly human-modified landscapes.
Author Keywords: animal abundance, black bear, capture-recapture, density estimation, statistical ecology, wildlife management
Managing Through Change: Indigenous knowledge, climate change and the case of moose in Nunatsiavut
Arctic ecosystems are increasingly altered by climate change, and some wildlife species, like moose, are adapting to these new conditions. Indigenous knowledge and values, such as those held by Inuit, can provide insight into adaptive wildlife management and may improve ecosystem resiliency. This thesis seeks to address the following question: What is the potential role of Indigenous knowledge in managing wildlife under climate change? This thesis follows a qualitative exploratory design involving 1) a systematic literature review of the peer-reviewed literature and 2) a case study on moose in Nunatsiavut in which 35 interviews and participatory mapping were conducted with Inuit beneficiaries. The results demonstrate a range of potential roles for Indigenous knowledge and values in managing species impacted by climate change. The case study of moose in Nunatsiavut has applicability across the Canadian Arctic where the sustainability of harvested species is at risk.
Author Keywords: Arctic, climate change, Indigenous knowledge, moose, Nunatsiavut, wildlife management
(Re)encountering black bears: Exploring the conceptualizations of human-bear interactions within Ontario
This thesis explores the perceptions of human-bear interactions in Ontario, suggesting that they have been shaped by narratives that have roots in colonial perceptions of nonhuman animals. Further, I seek to consider how these interactions could unfold differently if we rethought our relationships and responsibilities to these beings, in particular through an embrace of Indigenous-led conservation informed by ideas of animal welfare. The methods used for this research were first empirical, through qualitative data collection via interviews. Second, it was interpretive, through the observation of bear experiences and through the analysis of circulated and conceptual themes of bear information found in media articles. What emerged was an understanding that the mitigation efforts which are used when human-bear interactions occur are deeply influenced by political, social, and cultural factors that cannot be removed from these matters, asserting that a reconceptualization of current conservation frameworks needs to be considered.
Author Keywords: Compassionate conservation, Human-bear interactions, Human-wildlife relations, Indigenous conservation, Narrative inquiry, Wildlife conservation
The evolutionary ecology of Alaska's mountain goats with management implications
The integration of genetic and environmental information can help wildlife managers better understand the factors affecting a species' population structure and their response to disturbance. This thesis uses genetic techniques to assess the broad and fine scale population structure of mountain goats in Alaska. The first chapter aims to determine the number of genetically distinct subpopulations and model the demographic history of mountain goats in Alaska. The second chapter investigates the population structure and demographic history of mountain goats in Glacier Bay National Park and examines the impact that climate change will have on these mountain goats. My results indicate that Alaska has eight subpopulations which diverged during the Wisconsin glaciation. In Glacier Bay, population structure is reflective of the landscape during colonization, and mountain goat population density and movement corridors are likely to decline due to future climate change.
Author Keywords: Alaska, biogeography, gene flow, landscape genetics, mountain goat, population genetic structure
Robust assessment of changes in wild mammal occupancy and activity relative to livestock and human disturbance
Anthropogenic activities such as human activity and livestock grazing are responsible for the global rise in disturbance impacts on wildlife and may underlie regional changes in biodiversity and ecosystem dynamics. Few studies have tried to disentangle the effects of different anthropogenic activities on wildlife behaviour, leaving a major gap in our understanding of conservation and management needs in disturbed areas. Human activity and livestock grazing are increasing in spread and intensity worldwide, thereby imposing pressure on both wildlife and natural areas. In this thesis, I used a camera trapping and occupancy modeling framework to assess whether human presence and livestock grazing had different impacts on site occupancy and activity of 10 wild mammal species, and how responses differed across taxa. Specifically, I predicted that all species would be sensitive to disturbance, but the type and intensity of the response would depend on disturbance type. I detected different responses to each disturbance type across species, but response type (displacement, activity change, crepuscularity) was not associated with species characteristics such as body. Importantly, disturbance intensity had a strong effect on wildlife activity levels, with many species exhibiting marked reductions in activity at high human or livestock disturbance intensity. It remains unclear whether all species' responses are a direct consequence of disturbance versus indirect outcomes of shifts in behaviour of other species in the wildlife community (i.e., disturbance-related changes in prey activity may affect predator activity). Although on the whole disturbance intensity and effect sizes tended to be relatively low in this study, responses were exhibited across all species, implying that disturbance responses may be universal in wild mammals and largely underestimated. Ultimately, my work offers a template for the robust assessment of disturbance impacts on wildlife and provides new avenues for future research to deepen our understanding of wildlife sensitivity to anthropogenic activities.
Author Keywords: activity, anthropogenic disturbance, human activity, livestock, occupancy, wildlife
ECTOPARASITIC INFLUENCES OF DIPTERA ON THE ACTIVITY AND BEHAVIOUR OF WOODLAND CARIBOU (RANGIFER TARANDUS) IN A MANAGED BOREAL FOREST LANDSCAPE IN NORTHERN ONTARIO
Caribou experience direct and indirect negative effects of harassment from biting flies, influencing behavior and activity on several spatial and temporal scales. I used systematic insect collection surveys during the summers of 2011 and 2012 to examine the spatial and temporal distributions of black flies (Simuliidae), mosquitoes (Culicidae), and deer flies and horse flies (Tabanidae) in a managed boreal forest in northern Ontario. Mosquitoes had a positive association with densely treed habitats, whereas black flies more often occurred in open areas, and tabanids had a strong presence in all habitat types. Habitats in proximity to large bodies of water had fewer biting flies than inland areas. Young stands supported higher abundances of tabanids despite vegetation community type. Next, I tested for seasonal effects of biting fly abundance on caribou activity by modelling the seasonal trend in abundance for each fly family for each year and compared this to an index of daily activity for 20 radio-collared female caribou in 2011 and 10 females in 2012. I modeled this index of caribou activity for each animal in each year and extracted the set of partial correlation coefficients from multiple regressions to test for effects of biting fly abundances on caribou activity. Caribou reduced their daily activity when tabanids were more numerous, and increased activity when mosquitoes were numerous. This divergent response may reflect a difference in the efficacy of moving to reduce harassment, owing to the stronger flight capabilities of tabanids.
Author Keywords: Activity, Anthropogenic Disturbance, Behaviour, Insect harassment, Temporal distribution, Woodland Caribou
Evaluating the Effects of Habitat Loss and Fragmentation on Canada Lynx
Current major issues in conservation biology include habitat loss, fragmentation and population over-exploitation. Animals can respond to landscape change through behavioural flexibility, allowing individuals to persist in disturbed landscapes. Individual behaviour has only recently been explicitly included in population models. Carnivores may be sensitive to changing landscapes due to their wide-ranging behaviour, low densities and reproductive rates. Canada lynx (Lynx canadensis) is a primary predator of snowshoe hares (Lepus americanus). Both species range throughout the boreal forests of North America, however lynx are declining in the southern range periphery. In this dissertation, I developed new insights into the effects of habitat loss and fragmentation on lynx. In Chapter 2, I created a habitat suitability model for lynx in Ontario and examined occurrence patterns across 2 regions to determine if habitat selection is flexible when different amounts of habitat are available. Although lynx avoided areas with <30% suitable habitat where suitable land cover is abundant, I found that they have flexible habitat selection patterns where suitable land cover is rare and occurred in low habitat areas. In Chapter 3, I investigated the effects of dispersal plasticity on occupancy patterns using a spatially explicit individual-based model. I showed that flexible dispersers, capable of crossing inhospitable matrix, had higher densities and a lower risk of patch extinction. In contrast, inflexible dispersers (unable to cross inhospitable matrix), were most limited by landscape connectivity, resulting in a high extinction risk in isolated patches. I developed three predictions to be explored with empirical data; (1) dispersal plasticity affects estimates of functional connectivity; (2) variation in dispersal behaviour increases the resilience of patchy populations; and (3) dispersal behaviour promotes non-random distribution of phenotypes. Finally, in Chapter 4, I examined the consequences of anthropogenic harvest on naturally cycling populations. I found that harvest mortality can exacerbate the effects of habitat fragmentation, especially when lynx densities are low. Dynamic harvest regimes maintained lynx densities and cycle dynamics while reducing the risk of population extinction. These results suggest that lynx display some flexibility to changing landscapes and that the metapopulation structure is more resilient to increasing habitat loss and fragmentation than previously understood. Future studies should focus on determining a threshold of connectivity necessary for population persistence and examining the effects of habitat loss on the fecundity of lynx.
Author Keywords: Fluctuating Populations, Habitat Fragmentation, Landscape Ecology, Occupancy Dynamics, Population Ecology, Spatially Explicit Population Models