Grizzly bear behavior in south-central Alaska: Use of a hidden Markov model to assess behavior

Attempts to understand wildlife population dynamics and implement management practices benefit from understanding animal behavior traits. In Alaska, USA, grizzly bear (Ursus arctos) behavior is important to understand because the species is an apex predator, exerts top-down population effects, and is a cornerstone species across complex landscapes. Our objectives were to examine how environmental and anthropogenic factors affect behavior patterns in grizzly bears in south-central Alaska. We hypothesized that, for a given sex, the time spent by bears resting, foraging, and traveling are similar and show consistent seasonal shifts as resource availability changes throughout their nondenning season. Additionally, we hypothesized that males spend more time traveling than do females because of differences in home range sizes, metabolic needs, and the rearing of cubs associated with females. We used a hidden Markov model (HMM) to test our hypotheses and examine how various dynamic, static, and temporal variables affected bear (n = 12) behavior during the summers of 2021–2022. Males spent the most time foraging and the least time resting while females spent the most time resting and the least time foraging. These patterns shifted as the summer progressed with increases in traveling and foraging and decreases in resting for both sexes. Bears were found to be most likely in a resting state at hotter temperatures and more likely to be traveling at colder temperatures. Additionally, bear behaviors deviated depending on elevation, whereby bears were foraging at higher elevations and resting or traveling at lower elevations. Our findings indicate that male–female differences in behavior are seasonally dependent, being similar in autumn and opposite during the postdenning period. In addition, we see evidence that changes in environmental conditions, such as warming, can have direct effects on behavior. Further studies should explore how future environmental and anthropogenic factors such as predicted changes in climate and increases in land-use changes can affect bear behavior and subsequent demographic effects.