| Summary: | Although numerous examples exist of intra-guild dietary separation among co-existing species, studies of spatio-temporal niche partitioning among species sharing a single food resource are rare. I investigated spatio-temporal patterns of multi-species predation on moose (Alces alces) calves in an Alaskan boreal forest community where moose are the only large herbivore, and constitute the primary prey of co-existing black bears (Ursus americanus), brown bears (Ursus arctos), and gray wolves (Canis lupus). The two most closely related predators, black bears, and brown bears, overlapped temporally but segregated spatially in their consumption of moose calves. Moreover, both bear species segregated spatially and temporally from wolves when killing moose calves. In addition, I recorded the movement patterns of 20 GPS-collared black bears from den emergence to onset of moose parturition in 2003. Over approximately 3 weeks prior to parturition, results from average distance calculations suggest that black bears moved closer to probable moose calving-site habitat. Likewise, the average proportion of seasonal habitat use by black bears surrounding dens reflected the same trend for areas where cow moose gave birth in spring 2003, with a propensity to use needleleaf forest more than any other habitat. The objective of my final study was to document habitat use of GPS-collared black bears during peak and non-peak seasons of black bear-induced and brown bear-induced moose calf mortality within southwestern interior Alaska, in spring 2002. Results from this study suggest that GPS-collared black bears use the same habitat as conspecifics more often than expected during the peak period of predation on moose calves by black bears, whereas GPS-collared black bears use habitat as it is available during the peak period of predation on moose calves by brown bears. GPS-collared black bears have a tendency to use mixed-deciduous forest and needleleaf forest less than expected as compared to that of black bears and brown bears during non-peak portions of the season of predation. The outcome of my graduate research offers possible explanations (e.g., sex, age) for spatial overlap or segregation in one member of a complex predator guild in relation to a seasonal pulse of preferred prey.
|
|---|