Date of Award:
Doctor of Philosophy (PhD)
Lise M. Aubry
The New Jersey Division of Fish and Wildlife (NJDFW), in collaboration with Bear Trust International, presented us an opportunity to examine a long-term (33 years) American black bear (Ursus americanus) data set from northwestern New Jersey (NJ), USA. State agencies continue to grapple with uncertainty about the efficacy of socially divisive management actions such as recreational harvest and lethal control as tools to reduce escalating human-bear conflicts. We applied multistate capture-reencounter models to a large sample of black bear captures (>5,000) and dead recoveries (>1,300) between 1981 – 2014 to estimate cause-specific mortality and spatial dynamics between wildland and anthropogenic habitats. Additionally, we assessed temporal correlations between more than 26,500 reported human–black bear interactions and mortality rates. Adult females were twice as likely (0.163 ± 0.014) as males (0.087 ± 0.012) to be harvested, and cubs (0.444 ± 0.025) and yearlings (0.372 ± 0.022) had a high probability of dying, primarily from vehicle strikes. Nuisance behaviors reported declined with increasing harvest and lethal management (P = 0.028, R2 = 0.338). Adult bears previously designated as a nuisance and/or threat (hereafter, “problem”) were more likely to be harvested (0.176 ± 0.025) than those with no conflict history (0.109 ± 0.010).
Combined legal kills and vehicle strikes, the two greatest mortality causes for marked bears, occurred significantly less than expected per unit area in urban and agricultural areas, and more than expected in the wildland-urban interface and wildland habitats. Across all age-classes, problem bears were significantly more likely to transition to anthropogenic habitats, yet they died at lower rates than conspecifics with no history of conflict in wildlands. Cubs and yearlings died at significantly higher rates than adults in the risky interface habitat, corroborating independent estimates of their increased susceptibility to harvest and vehicle strikes. Ultimately, wildland habitats represented a population source (λ = 1.133) and anthropogenic habitats a sink (λ = 0.945). Harvest represents an important management tool to help meet population targets and decrease human-bear conflicts by disproportionately removing problem bears.
Raithel, Jarod D., "Integrating Black Bear Behavior, Spatial Ecology, and Population Dynamics in a Human-Dominated Landscape: Implications for Management" (2017). All Graduate Theses and Dissertations. 6633.
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