Cub’s adoption astounds park officials, tourists

CHEYENNE – A grizzly bear in Grand Teton National Park has wowed scientists and tourists alike by adopting a cub from another sow grizzly.

Park officials say such behavior is rare but not unprecedented. The switch is especially fascinating for having occurred between two grizzlies that are well-known – famous, practically – in the region for having spent so much time this summer near roads and developed areas where they’ve been easy to observe with their cubs.

What’s more, the bears are keeping it in the family: The adopting mother grizzly is the daughter of the grizzly that lost its cub.

“For the general public to find out that something like this could happen I think is a fascinating glimpse into bear behavior and what can happen among bears that are related,” Grand Teton spokeswoman Jackie Skaggs said Monday.

The switch occurred between a 15-year-old grizzly that biologists identified years ago with the number 399 and her daughter, a 5-year-old grizzly identified by the number 610.

Grizzly No. 610 gave birth to two cubs last winter. She has been seen with a third cub since late last week. Grizzly No. 399 gave birth to three cubs last winter but in the past few days has been seen with just two cubs in tow.

Research has shown that grizzlies sometimes will adopt cubs that become separated from their mothers. Separation can occur after a disturbance of some kind.

A brief separation apparently happened last month in the family of No. 610, when the mother grizzly was seen without her cubs and behaving in an agitated manner. She was spotted with her cubs again soon after, Skaggs said.

Some speculated a male grizzly might have disrupted the family. Each summer around June, male grizzlies are known to kill cubs to cause their mothers to go into estrus, when females are receptive to mating, Skaggs said.

Nobody knows how No. 399 might have become separated from her cub. But the switch occurred around the same time as reports of the sound of bears fighting in her territory last Thursday night, park biologist Steve Cain said.

Scientists haven’t confirmed beyond a shadow of a doubt, such as through DNA testing, that the new cub following No. 610 is the one lost by No. 399.

“The possibility exists that 399 lost a cub by another means and 610 gained one by a different family group,” Cain said. “But I would characterize that possibility as extremely low.”

While previous research has documented grizzlies swapping cubs in Yellowstone National Park, Cain said he’s never seen it in Grand Teton.

“It probably occurs in the wild more frequently than is ever documented because it’s a difficult type of occurrence to document,” he said.