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Black bear birth rates low after drought


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Dec 20, 2000
Jackson, Wyoming
Researchers say early indications show few yearlings and cubs.
By Deanna Darr
Jackson Hole Guide

Researchers are finding few black bear cubs and yearlings emerging from dens this spring, leading to speculation that two summers of drought may be affecting the species’ birth rate.

Ron Grogan, trophy game biologist for the Wyoming Game and Fish Department, said early-season den studies in the Dubois area have found no cubs in any of the three dens researchers have entered so far.

It’s a fairly unusual situation, but not entirely unexpected, according to Grogan.

Bears have a good ability to survive a bad food year, but after two consecutive years adult bears emerge from their dens in very poor condition, he said.

And while adult bears are able to survive, yearlings often are not, Grogan said. Adult females usually will not have cubs if they haven’t had adequate nutrition over the previous summer.

Grogan cited several examples of bears that researchers have found and tested so far. One 11-year-old female, in the prime of her reproductive years, left the den before researchers could locate her, but tracks and other signs indicated that she had no cubs.

“If any bear should have had cubs, she should have,” Grogan said.

The cumulative effect of two years of drought is also reflected in a 10-year-old female black bear that researchers have tracked for the past several years. Last year Grogan said the bear weighed 185 pounds in early spring. At the same time this year, she weighed only 94 pounds.

Early indications have shown that bears in the northern Yellowstone area are in slightly better condition than bears farther south. While no bears in the Jackson area are monitored, Grogan said he estimates that they will be in similar condition to those near Dubois.

Most bears will emerge from their dens between now and the first week of May, and Grogan said they will immediately begin their search for food, which is critical to their survival.

He said bears emerged in better condition last year, but as the year progressed and food became scarcer there were more reports of conflicts between bears and humans as bears sought new sources of food.

Also, some cubs born last year were weaned early and abandoned by their mothers. Grogan said those orphaned yearlings had a very low chance of survival without their mothers.

Grogan said the most immediate effect of this year’s low birth rate will be a lull in reproduction for the next few years, but it does not necessarily mean a crash in the black bear population.

Researchers will continue to monitor the health of the black bear population as they also monitor grizzly bears. Grogan said researchers hope to collar roughly seven more female black bears over the summer to help them better assess the population.

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