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

Insertable 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.Annual 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.Data loggers (archival tags) that are attached or surgically implanted in animals to collect and store or relay information about activity, movements, physiology, and the local environment are becoming increasingly sophisticated and useful to biologists [1,2]. Such devices have been used to monitor heart rate and activity of free-ranging reptiles, birds, and mammals [3-5]. With rapid advancements in electronics over the past decade, data logger packages have become smaller and less invasive while the period of monitoring has increased from days to months, and rarely up to 1 year [6,7]. With the aid of these devices, biologi