A mountainside overlooking traffic on U.S. Highway 550 might seem like an odd place to find a black bear and her two cubs.
But a 222-pound mama bear has made her home in just such a place underneath a boulder on Animas Mountain north of town.
Heather Johnson, a wildlife researcher with Colorado Parks and Wildlife, is tracking the bear, known as B52, and 34 other female bears as part of a six-year study to understand bear populations and behavior near urban environments.
“We are finding, certainly, the local population is not increasing,” Johnson said of preliminary findings.
The study was inspired by increasing conflicts between bears and humans in Colorado, which had lead researchers to assume the population was rising, Johnson said.
Last week, the group checked on B52, crawling into her den where she is hibernating to jab her with a safe, short-term anaesthetic. Once she had fallen asleep, the team brought her into the sunshine with her two 3-month-old cubs.
“She’s got a beautiful coat,” Johnson noted.
The team wrapped the cubs in winter jackets while it put their mom on oxygen to collect information about her health. The crew also downloaded GPS information from her collar.
The collars on the bears register a location every hour except in winter. This allows researchers to understand the bears’ ranges in detail. Of the 75 bears tracked during the study, one bear traveled south of Chama, New Mexico, and back to Durango with cubs in tow. But B52 is content to stay closer to town.
“With these bears that are collared, we get really good, fine-scale data of where they are going, what they are doing,” Johnson said.
The group also took hair and blood samples.
“We really want to make it worth it for them and for us to collect as much information as we can,” Johnson said.
From the hair samples, Johnson will be able to find out how much processed human food the 8-year-old bear has been eating.
During the first five years of the study, Johnson discovered that bears eating human foods from trash cans have higher reproductive rates than those living on natural foods. But the survivorship of those cubs is lower, Johnson said.
“There’s a lot more risks for a little bear in town,” she said.
For example these cubs can get run over, separated from their mothers or electrocuted climbing power poles, she said.
It is impossible to say whether cubs learn to rely on human food from their mothers, and that is outside the scope of the study.
Both cubs on Animas Mountain were microchipped so if one dies near town or it is killed by a hunter, it can be identified by Colorado Parks and Wildlife. This is part of the effort to track bear populations more effectively.
In many areas across Colorado, a good population estimate is not available.
“It’s really tough problem: “How many bears are out there, and what kind of impact are we having?” said Stewart Breck, a wildlife ecologist with the National Wildlife Research Center.
So in addition to gathering exact GPS data, Colorado Parks and Wildlife set up scent baits around Durango to collect hair.
This helped them determine how well hair snares work for estimating population and may help refine the process.
Getting an accurate count of bears will help Parks and Wildlife manage the population.
The study focusing on the Durango area is scheduled to end next winter.