In 1989 a grizzly bear north of Gardiner, Mont., had twins. The next year, the bear, a known nuisance raiding an apple orchard and chicken coop, got into trouble one too many times.
Wildlife managers relocated the sow to the southeast corner of Yellowstone National Park. Its young, a year-old and known as yearlings, were sent to the northwest corner of Grand Teton National Park in hopes separating the family would prevent the yearlings from learning behavior that could later get them in trouble.
One of the young, tagged No. 179 for monitoring purposes by biologists, would go on to birth at least 10 offspring recorded by scientists, and it never got into major trouble again.
Bear No. 179 is a perfect example of how yearlings can thrive when separated from sows translocated due to conflicts, said Mark Haroldson, supervisory wildlife biologist with the USGS Interagency Grizzly Bear Study Team.
Researchers log data on every grizzly handled in the Greater Yellowstone Ecosystem since the 1970s. Haroldson is using data on sows with young relocations between 1981 and 2013 to track what happens to the offspring of bears.
He’s finding survival rates are nearly identical for yearlings translocated with the mother and those moved separately. The separate relocations came either because the mother was killed, or because managers worried the yearlings would learn bad behavior if they stayed with the mother.
The study is still in-process, and Haroldson has not published his initial findings, although he did present it at the Biennial Scientific Conference on the Greater Yellowstone Ecosystem this fall.
Haroldson’s data included 28 yearlings moved with their mothers, and 25 moved without, after management captures. Survivorship within the first year after transport was 61 percent for those yearlings moved with their mother and 68 percent for those transported without. Of 38 yearlings moved four or more years ago, 56 percent of the 16 yearlings translocated with the mother reached age 5, while 41 percent of the 22 moved without the mother lived that long.
In Greater Yellowstone, the probability a yearling lives to age 5 is about 47 percent, Haroldson said. The yearlings, moved with or without their mother, were about average in survivorship.
The similarities in the survival rates of the two groups, both for the first year after relocation and five years later, supports an additional management strategy. If wildlife managers decide yearlings will learn bad behavior, such as mimicking the mother’s use of livestock or apple orchards as a food source, it might benefit the young bears if they are separated from the mother. It also shows that if the mother can’t be captured and moved, the yearlings can still survive if they are moved on their own.
How biologists manage conflict bears depends on the offense, the bear’s history and where it happens. There isn’t set protocol, Haroldson said.
So far in 2014 only two yearlings — siblings — have been moved. Their mother was involved in cattle depredation and eluded capture, so the young were moved alone.
Wyoming Game and Fish staff who move conflict bears work hard to capture and move the entire family, said Dan Bjornlie, large carnivore biologist with the agency.
“But if we can’t capture the yearlings for some reason, or the situation dictates that it’s better to move them separately, we now know we can do that and the yearlings have a good chance of survival,” he said.
Data on bear conflicts and captures hasn’t been completed yet for 2014. In 2013, there were 26 bears captured due to conflicts. Of the 18 bears relocated there was only one female with yearlings and the unit was moved together, according to Bjornlie. The trio was moved to Togwotee Pass. Biologists collared the mother, but not the young. All three were spotted in early May together and then separately, as is normal for 2-year-olds, later in the summer.
Unlike cubs-of-the-year that couldn’t survive on their own, yearlings, especially in the fall, can weigh up to 170 pounds, nearing the 250-pound average of an adult female. The last thing yearlings do with their mother is den and they split up naturally in the spring. The bears have already denned once with the mother and can do it on their own.
Knowing yearlings can be moved separately from their mother and still survive to adulthood gives hope in cases where the mother is killed in an incident or due to repeat offenses, or needs to be moved elsewhere, Bjornlie said.
“The main issue is, we thought for a long time yearlings without mothers were basically lost to the population,” he said. “(We thought) their chances of survival are very, very low. They aren’t going to make it. They aren’t going to contribute. What we’re finding is that is not necessarily the case. We know now these yearlings have a decent chance of surviving on their own.”
Haroldson, who hopes to publish his findings in the spring, wants to explore other variables that could influence which bears survive, such as the weight of the bears when moved, the population density in the new areas and available food.
Bjornlie, who often works on data analysis projects with Haroldson, also wants to look at other reasons some yearlings survive.
“There are quite a few questions we can add into the work (Haroldson’s) already done,” Bjornlie said.
As for bear No. 179, its mother died in a conflict with a hunter in 1996. Its sister found success after its relocation. The last verified contact with it was in 1996. No. 179 dropped its last collar in October 2013 and was sighted this year. It was 24 years old and was spotted with cubs.
— “Peaks to Plains” is a blog focusing on Wyoming’s outdoors and communities. Kelsey Dayton is a freelancer and the editor of Outdoors Unlimited, the magazine of the Outdoor Writers Association of America. She has worked as a reporter for the Gillette News-Record, Jackson Hole News&Guide and the Casper Star Tribune. Contact Kelsey at [email protected] Follow her on twitter: @Kelsey_Dayton
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