Biologists put a collar on her in 1992. They called her Xina.
She outlived other black bears, including many of her own cubs, and the original study of which she was a part. The biologists who tracked her collar believes Xina was 31 and the oldest documented bear in state history when she died last month.
“This bear’s the oldest known bear in Utah — period," said Hal Black, a professor emeritus of wildlife biology at Brigham Young University and one of the researchers who tracked Xina.
A Utah Division of Wildlife Resources biologist in mid-June received what is called a mortality signal from her GPS collar — an alert the animal had not moved in 24 hours. Biologists found Xina’s remains in the Book Cliffs of eastern Utah about 1.5 miles from where she made a den in the fall and in the same canyon where she was first trapped.
Black bears rarely live to 30, Black said. In dry years, the Book Cliffs, a string of desert mountains, don’t have much fruit or foliage for the bears to eat. And while researchers studied a black bear in Minnesota to age 39, they didn’t begin tracking her until age 7, meaning they missed documenting her early reproductive history.
Xina was 4 and had not yet had her first litter of cubs when she was collared, Black said. A staffer who helped capture her had a wife named Christina. The husband called his wife Xina for short. The name was passed onto the bear.
Black said Xina was one of about 50 adult, female bears tracked as part of a study on their reproductive performance. The study, conducted by personnel or with support from DWR, the Bureau of Land Management, BYU and private donors, ran from 1991 to 2002 and resulted in two or three scientific papers, Black said, and a large report from DWR.
Those first litters for Xina didn’t go well. One of 14 cubs survived to be a yearling, Black said.
“So she looked sort of like a loser," Black said.
Xina then gave birth to a litter of three cubs. When researchers went back the next year, Black said, they expected those cubs would be dead, too.
Instead, all three cubs were healthy and split from their mother on the species’ typical schedule. Adult females tend to give birth every two years, Black explained, and the next litter of three cubs survived to leave the den, too.
Researchers continued tracking and studying Xina even after the initial study ended, going every two years to replace her collar while she hibernated. Late in Xina’s reproductive years, researchers were surprised to find Xina had allowed a 2½-year-old son to stay with her in the den.
Mother bears typically turn inattentive to their cubs when they turn 15 or 16 months old, spurring the cubs and mother to separate. Xina’s care for the older offspring, Black said, led to a theory that older mother bears might invest more in their cubs than younger moms.
Xina stopped procreating about eight years ago, Black said. Her death is believed to have come from natural causes, not from any hunter or predator.
She might yield scientific findings yet, Black said. Researchers recovered her femurs and other parts of her skeleton to turn over to an orthopedic specialist to determine the level of osteoporosis.
Correction • July 30, 8:45 a.m.: Due to incorrect information from the Utah Division of Wildlife Resources, the bear’s name was misspelled in a previous version of this story.