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Seasonal Variation in American Black Bear Ursus americanus Activity Patterns: Quantification Via Remote Photography

Bridges, Andrew S., Vaughan, Michael R., Klenzendorf, Sybille
Wildlife biology 2004 v.10 no.4 pp. 277-284
Ursus americanus, animals, autumn, cameras, evolutionary adaptation, habitats, nocturnal activity, photography, plasticity, radio telemetry, seasonal variation, summer, Allegheny Mountain region, Virginia
Activity pattern plasticity may serve as an evolutionary adaptation to optimize fitness in an inconstant environment, however, quantifying patterns and demonstrating variation can be problematic. For American black bears Ursus americanus, wariness and habitat inaccessibility further complicate quantification. Radio telemetry has been the primary technique used to examine activity, however, interpretation error and limitation on numbers of animals available to monitor prevent extrapolation to unmarked or untransmittered members of the population. We used remote cameras to quantify black bear activity patterns and examined differences by season, sex and reproductive class in the Alleghany Mountains of western Virginia, USA. We used 1,533 pictures of black bears taken during 1998–2002 for our analyses. Black bears generally were diurnal in summer and nocturnal in autumn with a vespertine activity peak during both seasons. Bear-hound training seasons occurred during September and may offer explanation for the observed shift towards nocturnal behaviour. We found no substantial differences in activity patterns between sex and reproductive classes. Use of remote cameras allowed us to efficiently sample larger numbers of individual animals and likely offered a better approximation of population-level activity patterns than individual-level, telemetry-based methodologies.