A bear cub is kept warm as it is prepared to be weighed by Colorado Parks and Wildlife field technicians during the examination of female bear No. B52 outside of her den on Animas Mountain. Photo by Shaun Stanley/Durango Herald.

Colorado Parks and Wildlife biologist Heather Johnson, left, and field technician Cody Wallace examine female bear No. B52 outside of her den on Animas Mountain. Photo by Shaun Stanley/Durango Herald.

Colorado Parks and Wildlife biologist Heather Johnson examines the teeth of female bear No. B52 that was examined outside of her den on Animas Mountain. Photo by Shaun Stanley/Durango Herald.

Colorado Parks and Wildlife field technicians prepare to approach the den of female bear No. B52 at her den on Animas Mountain for research purposes. Photo by Shaun Stanley/Durango Herald.

Colorado Parks and Wildlife biologist Heather Johnson examines the teeth of female bear No. B52 that was examined outside of her den on Animas Mountain. Photo by Shaun Stanley/Durango Herald.

A bear cub is prepared to be weighed by Colorado Parks and Wildlife field technicians David Lewis, center, and Tana Verzuh during the examination of female bear No. B52 outside of her den on Animas Mountain. Photo by Shaun Stanley/Durango Herald.

Colorado Parks and Wildlife biologist Heather Johnson readies a dosage of tranquilizer that will be administered to bear No. B52 before it is examined on Animas Mountain. To the left of Johnson, David Lewis with Colorado Parks and Wildlife prepares records to be kept during the examination. Photo by Shaun Stanley/Durango Herald.

Colorado Parks and Wildlife field technician Cody Wallace tracks the signal from the radio collar of female bear No. B52 in her den on Animas Mountain before the team moves closer to tranquilize it for research purposes. Photo by Shaun Stanley/Durango Herald.

Heather Johnson, a Colorado Parks and Wildlife biologist, examines the foot of female bear No. B52 outside of her den on Animas Mountain. Photo by Shaun Stanley/Durango Herald.