An Improved Method of Documenting Activity Patterns of Post-Emergence Polar Bears (<i>Ursus maritimus</i>) in Northern Alaska

Abstract

Throughout their circumpolar range, pregnant female polar bears (Ursus maritimus) create snow dens in which they give birth to altricial cubs. Because polar bear neonates are born in such an undeveloped state, their survival requires a long, undisturbed period of in-den development. To mitigate human impacts on denning bears, it is necessary to understand the chronology of denning, the behaviors of denning bears, and their sensitivity to human activities. Since 2002, we have studied the den emergence behaviors of polar bears in northern Alaska; however, we moved from using on-site observers (2002-03) to using autonomous video systems (2005-08). Here we compare the duration, activity budgets, and behaviors of polar bears to see whether observation methods affected their activities. Camera systems recorded nearly 10 times the data per den recorded by human observers (526 h/den and 57 h/den respectively). We found no difference between the two study periods in emergence dates, duration at den sites, abandonment dates, or activity budgets for polar bears. We observed a 16-fold reduction in the number of bear-human interactions when using cameras instead of human observers. There was, however, a marked increase in the intensity of response when using cameras (125 m) as compared to observers in blinds (400 m). An understanding of these activity patterns can be used to manage human activities near dens so as to minimize disturbance.

Polar bears experience skeletal muscle atrophy in response to food deprivation and reduced activity in winter and summer

“…Importantly, at the time of sampling in April–May, all individuals may have been successfully hunting for several weeks. The mean sampling date (5 May) was ~8 weeks after females with new cubs typically emerge from dens (13 March; Smith et al , 2013 ) and ~3 weeks after the peak of parturition season for ringed seals ( Smith, 1987 ). Third, individuals that remained active may have experienced winter food deprivation resembling the complete fast of hibernation, and the associated degree of atrophy.…”

Efficacy of aerial forward-looking infrared surveys for detecting polar bear maternal dens

“…We assessed the efficacy of industry AFS for polar bear den site detection by comparing AFS data from 2004-2016 with ground-truth data we collected during research we conducted on emergence behaviors of denning polar bears between 2002 and 2016 in the same area [3,18]. We monitored maternal dens by direct observation and by placement of video cameras that recorded bear activity.…”

“…We monitored maternal dens by direct observation and by placement of video cameras that recorded bear activity. In this manner we were able to ascertain the precise timing of den opening, duration of stay post-breakout, and when family groups abandoned dens [3,18].…”

Polar bear mother‐offspring interactions in maternity dens in captivity

“…Cameras enable observations of the behavioural development of the cubs and of activities within the den, whereas in the wild, bears must be observed from a distance [Greenwald and Dabek, ; Smith et al, ]. Few studies have been conducted on the denning behaviour of polar bear mothers and cubs, they are usually studied when they emerge from the den [Hansson and Thomassen, ; Smith et al, .]. Little is known, however, about the behaviour and vocalisations in the den [Derocher et al, ].…”