Assessing American black bear response to human activity at Kenai Fjords National Park, Alaska

Abstract

We measured American black bear (Ursus americanus) responses to hikers, small power skiffs, kayakers, and overnight campsites within coastal salt marsh foraging areas. To accomplish this, we experimentally approached bears in the intertidal and supratidal zones of Aialik Bay (AB) and Nuka Bay (NB), Kenai Fjords National Park, Alaska. We chose these areas due to their different levels of human activity (AB = high, NB = low). In the first experiments, we determined the overt response distances (ORD: when bears first responded to our approaches) and flight initiation distances (FID: the distance at which bears were pushed from their original location) for 118 black bear groups involving 136 bears. We found no difference between ORD response to power skiffs and versus kayaks, nor between those responding to kayaks versus foot approaches. However, bears first responded to power skiffs 50 m farther than first responses to foot approaches. There was no difference in FID between all modes of approach. There were no differences in response intensities (a qualitative scale depicting strength of bear response to human presence at both the ORD and FID) between any of the modes of approach. There were no differences in bear minutes/hour (minutes of bear presence in the study area/hour of observation) or numbers of bears at NB and AB before or after campsites were present. There was, however, a difference in levels of bear activity in NB and AB when campsites were in place: AB bear minutes/hour decreased by 50% and NB bear minutes/hour increased by 75%. We recommend minimum approach distances of 170 m for skiffs and kayaks and 116 m for hikers to minimize bear displacement by visitors to the park. Additionally, we suggest people avoid camping in saltmarsh areas so as to leave bears undisturbed.