Physiological reactions to capture in hibernating brown bears.

Alina L Evans,Ole Frobert,Jon M Arnemo,Boris Fuchs,Timothy G Laske,Stéphane Blanc,Andrea Friebe,Navinder J Singh,Jon E Swenson

doi:10.1093/conphys/cow061

Abstract

Human disturbance can affect animal life history and even population dynamics. However, the consequences of these disturbances are difficult to measure. This is especially true for hibernating animals, which are highly vulnerable to disturbance, because hibernation is a process of major physiological changes, involving conservation of energy during a resource-depleted time of year. During the winters of 2011-15, we captured 15 subadult brown bears (Ursus arctos) and recorded their body temperatures (n=11) and heart rates (n =10) before, during and after capture using biologgers. We estimated the time for body temperature and heart rate to normalize after the capture event. We then evaluated the effect of the captures on the pattern and depth of hibernation and the day of den emergence by comparing the body temperature of captured bears with that of undisturbed subadult bears (n=11). Both body temperature and heart rate increased during capture and returned to hibernation levels after 15-20 days. We showed that bears required 2-3 weeks to return to hibernation levels after winter captures, suggesting high metabolic costs during this period. There were also indications that the winter captures resulted in delayed den emergence.

Highlights

Wild animals, including brown bears (Ursus arctos), are captured for a variety of research and management purposes.Assessing the potential negative effects of these captures is an ethical imperative
The hibernation pattern between captured and undisturbed bears is visually different for Tb and HR (Fig. 1)
Based on GPS positions, only two bears remained at the den site, with 10 and 11 day disturbance periods based on Tb

Summary

Introduction

Wild animals, including brown bears (Ursus arctos), are captured for a variety of research and management purposes. Bears exhibit a less dramatic drop in body temperature (Tb), protein conservation, absence of urination and defaecation (Hellgren, 1998) During hibernation, both captive and wild brown bears reduce their Tb by about 3–5°C from active levels of 37.0–37.5°C (Hissa, 1997; Evans et al, 2016) and heart rate (H) from about 70–. That study further investigated 18 cases of den abandonment and found evidence of human activity in 12 cases and could not exclude human activity in the remainder (Swenson et al, 1997) Both the Scandinavian brown bear and American black bears (Smith, 1986) are reported to find a new den within several weeks of disturbance, in some cases with. We used biologgers to document how winter captures affected hibernation patterns, depth and phenology

Materials and methods

Results

Discussion