Abstract 99 – Factors Influencing Duration of Behaviors in American Black Bear (Ursus americanus) Adult Females and Their Cubs Surrounding Hibernation

Brogan Holcombe, J. Bernardo Mesa-Cruz, Marcella J. Kelly

Hibernation behavior is understudied in American black bears (Ursus americanus), with most
knowledge stemming from post-hibernation emergence studies. Temperature and photoperiod
have been identified as potential drivers of the timing of hibernation but are also linked to food
availability. We explore drivers of bear activity surrounding hibernation using a unique video-
recorded data set of four temporarily captive female bears with cubs in a food-controlled
environment. We subset 22,000+ hours of video into two interval cycles to 1) analyze adult
behavior from September 2015 to May 2016 and 2) analyze mother-cub interactions post-birth,
including whether mothers showed bias towards biological vs. foster cubs. We consolidated 58
behaviors into three broad classifications (active, passive alert, passive) and found that the
hibernation stage, time of day, and interaction between photoperiod and temperature were
associated with changes in adults’ activity levels. During hyperphagia, post-birth, and
emergence stages, increased activity levels were driven by both higher temperature and
photoperiod, but the onset of hibernation was primarily driven by temperature only. We
further found that mother bears did not spend significantly more time with either cub group,
indicating no bias toward biological vs. foster cubs. Additionally, cubs did not show more
dominant (i.e., bullying) behaviors toward foster than biological siblings, providing evidence of
successful foster cub litter integration, which is promising for orphan cub fostering programs.
Finally, our results indicate that rising temperatures regionally could be responsible for
increased active behaviors, especially during hibernation onset, which could lead to increased
human-bear interactions on the landscape.