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The Department of Natural Resources is tracking about 20 bears fitted with GPS or VHF-radio collars as part of its northwestern Minnesota study, and plans are in the works to fit additional bears with the collars this summer.
As part of the study, the DNR in 2007 began capturing black bears in the northwest and fitting them with GPS and VHF-radio collars to learn more about the habitat they use at various times of year.
According to Dave Garshelis, a bear research biologist for the DNR in Grand Rapids, Minn., the study is focusing on northwestern Minnesota because it's a part of the state on the fringe of traditional black bear range.
The GPS collars record the bears' location every two hours. Early each winter, DNR crews trace the bears to their dens to change out the GPS collars and take them back to the lab to replace the batteries and download the data. They sub the collars with VHF units while the bears are hibernating and then return later in the winter to attach new GPS collars.
Mark Ditmer, a University of Minnesota graduate student overseeing the fieldwork, was in northwestern Minnesota this past week with Garshelis to change out the GPS and radio collars of denned-up bears and check on cubs. Ditmer will be back in the field this spring, capturing additional bears to collar and monitoring those already fitted with GPS units.
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The study, to date, has shown that male black bears in northwestern Minnesota have larger home ranges than populations anywhere else in North America. The northwestern males typically covered more than 450 square miles, compared with two square miles to 180 square miles in other parts of bear country.
Garshelis speculates the fragmented mix of agriculture fields and wooded country in northwestern Minnesota forces the bears to travel longer distances to find food.
Females, by comparison, seem to have smaller home ranges -- about 23 miles, which is within the range documented for female bears in other parts of the country.
The northwestern Minnesota bear project is scheduled to continue through winter 2011.
