Date of Completion
Black Bear, Density, Development, Exurban, Genetics, Landscape, Movement, Spatial
Dr. Tracy A.G. Rittenhouse
Dr. Lori S. Eggert
Dr. Jason C. Vokoun
Dr. Chadwick D. Rittenhouse
Dr. Issac M. Ortega
Field of Study
Natural Resources: Land, Water, and Air
Doctor of Philosophy
Global patterns of human land use have shifted towards increasingly sprawled development intermixed with natural land cover, creating coupled human and natural systems. To understand how these patterns may affect the persistence of wildlife populations, I studied changes in American black bear (Ursus americanus) population density, dispersal, movement behavior, and conflicts with humans across a gradient of development in Connecticut. Forest fragmentation, and intermixture with housing promoted conflicts between bears and people. Median census tract household income was associated with spatial autocorrelation in reported conflict locations, illustrating the importance of accounting for social carrying capacity in managing human-wildlife conflict in intermixed ecosystems. Variation in bear densities were more associated with housing density than forest cover, or a measure of intermixture. Bear densities were elevated in exurban, relative to rural areas, and decreased above 18 houses/km2 suggesting urban tolerance, rather than adaptation, among the Connecticut population.
Cohabitation with development can negatively impact wildlife populations, if population dynamics and evolutionary trajectories are detrimentally altered. Therefore, identifying changes in population dynamics and behavior in response to human development are important to wildlife conservation and management in intermixed ecosystems. To identify potentially maladaptive dynamics, I quantified changes in black bear dispersal, spatial genetic structure, and migration between differing levels of development. Increased housing density was associated with longer dispersal movements, and female philopatry was thus disrupted within more developed areas. Subpopulations occupying developed landscapes were not only sustained by local recruitment, but may serve as a source of female immigrants to surrounding areas.
I estimated selection for anthropogenic landscape features by black bears to discern movement patterns indicative of perceived risk, or habituation. Bears increasingly avoided housing and highways with increased intensity of development, and females with cubs were more avoidant of housing, providing evidence of perceived risk. However, bears decreased avoidance of development during hyperphagia, and exhibited increases in selection for roads and highways from day to night, indicating behavioral plasticity in response to perceived risk. Individual behavior in response to anthropogenic landscape features was highly variable within the population, indicating the potential for changes in the population mean.
Evans, Michael J., "Ecological Effects of Development on American Black Bear" (2016). Doctoral Dissertations. 1115.