They’re shadowy creatures, jet black with tooth and claw. They move silently on ninja feet. They’re big, they’re powerful, and they live among us. They’re black bears and lately they seem to be everywhere. Populations are rising and that means more contacts (and sometimes conflicts) with humans. It also means people are asking more questions about where all these bears are coming from. University of Wisconsin Madison grad student researcher Karl Malcolm wants to know too. Specifically, he wants to know how and when bears move away from their birthplaces in a process called dispersion. Malcom has radio collared more than 30 bears. The collars are advanced beyond the traditional telemetry devices of yesteryear. They each contain a GPS transmitter that allows researchers to track the bears via satellite. Funding for this research project includes support from the Wisconsin Bear Hunters Association and the Wisconsin Department of Natural Resources.
Black bears are born in mid winter and are tiny and helpless – totally dependent on their drowsy, semi-hibernating mothers for warmth and nutrition. Typically the cubs will stay with their mothers the next winter as yearlings. It’s at this point that Malcolm likes to sedate the mother and her young to do a health survey (body weight, blood samples) and fit them with collars. It’s a critically timed opportunity to do so because most of these yearlings will be off on their own by the next winter’s denning season. So far, Malcolm’s dispersion study has found that bears prefer to travel through contiguous strips of forest, including creek and river bottoms. They may venture out into open areas to feed (often at night) but will return to the forest for long distance travel. This research has shed much light on the movement of juvenile bears into new areas, but what about the apparent upswing in numbers?
Another UW Madison researcher, Dave McFarland, was an important contributor to newfound knowledge about bear populations. The Wisconsin population census had long been built on a flawed baiting technique that was due for a change. For some time Michigan and Minnesota have used a much more accurate technique that involves lacing bait with tetracycline, which bonds with the bear’s skeleton and is detectable in the bones of a harvested bear. McFarland’s use of tetracycline in his population research now suggests that the number of bears roaming Wisconsin may be two times or more what was previously thought.
Working with Malcolm and McFarland is Mike Gappa, an independent bear consultant and retired WI DNR bear specialist who believes the inaccuracy started in 1985 when the estimated population was conservatively calculated to be too low. Future population estimates were built upon that faulty information and continued to be incorrect until the recent change in census methodology. The results of the tetracycline study have breathed new life into the true number of bears in the wild. As might be expected, the number of hunting tags has been modified to reflect those new numbers. Gappa also believes that as bears disperse further south from their traditional northwoods strongholds into more agricultural areas, the wealth of available food has increased body weight and decreased disease and mortality. The bears are healthier and having more cubs. And what does that mean for us humans? Get used to listening for ninja feet.