Monitoring the wild black bear's reaction to human and environmental stressors

Abstract

BackgroundBears are among the most physiologically remarkable mammals. They spend half their life in an active state and the other half in a state of dormancy without food or water, and without urinating, defecating, or physical activity, yet can rouse and defend themselves when disturbed. Although important data have been obtained in both captive and wild bears, long-term physiological monitoring of bears has not been possible until the recent advancement of implantable devices.ResultsInsertable cardiac monitors that were developed for use in human heart patients (Reveal® XT, Medtronic, Inc) were implanted in 15 hibernating bears. Data were recovered from 8, including 2 that were legally shot by hunters. Devices recorded low heart rates (pauses of over 14 seconds) and low respiration rates (1.5 breaths/min) during hibernation, dramatic respiratory sinus arrhythmias in the fall and winter months, and elevated heart rates in summer (up to 214 beats/min (bpm)) and during interactions with hunters (exceeding 250 bpm). The devices documented the first and last day of denning, a period of quiescence in two parturient females after birthing, and extraordinary variation in the amount of activity/day, ranging from 0 (winter) to 1084 minutes (summer). Data showed a transition toward greater nocturnal activity in the fall, preceding hibernation. The data-loggers also provided evidence of the physiological and behavioral responses of bears to our den visits to retrieve the data.ConclusionsAnnual variations in heart rate and activity have been documented for the first time in wild black bears. This technique has broad applications to wildlife management and physiological research, enabling the impact of environmental stressors from humans, changing seasons, climate change, social interactions and predation to be directly monitored over multiple years.

Behavioral and physiological responses of American black bears to landscape features within an agricultural region

“…These two HR intervals were of different duration, and excluded eight hours per day, a constraint stemming v www.esajournals.org from the intended use of these devices in humans. Data were downloaded noninvasively during subsequent winter den visits using transcutaneous telemetry (CareLink Model 2090 Programmer with software Model SW007, Medtronic; details in Laske et al 2011). All methods and animal handling were approved by the University of Minnesota's Institutional Animal Care and Use Committees (1002A77516).…”

“…This investigation involved the portion of the year when bears were actively moving around the landscape, whereas most previous physiological measurements of bears focused on the denning period (Nelson et al 1983, Laske et al 2010, Laske et al 2011). Our first objective was to quantify the influence of movement on heart rate.…”

Implantation of subcutaneous heart rate data loggers in southern elephant seals (Mirounga leonina)

“…However, physiological stages between the two females could have been different: gestating or not, different success and duration of the previous foraging period at sea, impacting on their heart rate. This difference in heart rate could also be linked to differences in physical activity during the study (movements on land) or to the use of two different loggers between 10 ACCEPTED MANUSCRIPT heart rate (Reveal ® XT ICM on Ursus americanus, Laske et al 2011; DST micro-HRT on rats, Dudek et al 2015), further species-dependent studies are required to fully validate such data collection.…”

“…This was calculated from continuous monitoring of the subblubber electrocardiogram recorded from a differential voltage between two titanium electrodes. It also recorded the animal's physical activity (%) from a built-in accelerometer as the number of minutes spent in motion during 15 min intervals, and stored the timing of each heartbeat and daily activity (Laske et al 2011).…”

“…This technique avoids the necessity to glue devices to hair, but has never been used with phocids. Recently, fully implantable subcutaneous data loggers were used successfully to record heart rate in large mammal species (Ursus americanus, black bear; Laske et al 2011). However, in Mirounga angustirostris (northern elephant seal), subcutaneous loggers had to be removed after causing marked inflammation and infection (Green et al 2009).…”