Principal Investigator: 
Michael A. Sawaya, Ph.D. (Sinopah Wildlife Research Associates)

Background:
Water is essential for hydration in American black bears (Ursus americanus) and other species; however, its role in thermoregulation is poorly understood.  Black bears are particularly vulnerable to hyperthermia because of their large, warm-blooded bodies with dark, heat-absorbent coats, thick layers of fur and subcutaneous fat, and lack of functioning sweat glands.  In 2009, we deployed a remote camera network to examine patterns in wildlife distribution, abundance, and behavior at MPG Ranch in the northern Bitterroot Valley, Montana.  One of our many objectives was to learn more about the fascinating bear behavior that we observed at natural and artificial water sources.      

Objectives:
1) Document and describe black bear thermoregulatory behavior at water sources. 
2) Examine spatial and temporal patterns of bear use at natural and artificial water sources.

Study Area:
The 3,844-ha MPG Ranch study area where, in 2009, we established a network of remote cameras to monitor black bears and other wildlife in the northern Bitterroot Valley, Montana, USA. 

Results/Conclusions/Future Direction:
We detected male and female adult, subadult, and cub of year black bears immersing in water sources to thermoregulate.  Bear use was concentrated at one livestock tank, one road puddle, and one pond in areas with relatively little human disturbance.  Bear use steadily increased over summer, peaking in August when ambient temperatures were high and fat layers were thick.  Our results demonstrate that water is an important thermoregulatory resource for some bear populations, though more research is needed to understand how ursids use behavioral thermoregulation to dissipate excess body heat and avoid hyperthermia. 

To view some fun videos of bears in natural and artificial water sources, see our video on YouTube.  

For more details, see our paper in the peer-reviewed journal Ursus (pdf).