Oldest wolf in Yellowstone gives birth for the 10th time

For one graying wolf in the wilds of Northern Yellowstone, another year of life is synonymous with another year of pregnancy. It’s a rare feat, and also one that has enabled her survival in the wilderness.

Wolf 907 in Yellowstone National Park is well into her golden years. With one eye left, she’s considered elderly at the old age of 11. But that hasn’t stopped her from giving birth to another litter of pups, her tenth in fact.

She’s had a litter every year of her life since she was two years old. According to Kira Cassidy, a researcher with the Yellowstone Wolf Project, 907 gave birth to three pups this May. One has died; the other two are starting to venture farther away from the den hole as they near two and a half months of age.

“There is no evidence that wolves go through menopause, and so the thought is that they probably reproduce until they die. But because so many of them die when they're so young, there's just not much known about the ones that reach these kind of uber elder years,” said

With these two new pups, there’s currently 10 wolves in the Junction Butte pack — almost double since Wolf 907 took over the pack in 2017. In 2020, there were 35 pack members, making it the third largest in North America, so the number has largely decreased.

Unlike most packs, Wolf 907 has traded off the alpha position with some of her female relatives over the years. Usually, a wolf remains alpha until they die.

“We don’t really have a good explanation for that, other than the pack produces a lot of strong females,” Cassidy said.

She's a nepo-pup

Physiologically, a wolf can live to about the same age as a large dog — maybe 10 to 12 years old. However, the dangers of wolf life make it highly unlikely for them to die of old age. The average lifespan is 3 to 4 years old, making 907 a true outlier.

“They're extremely territorial with their neighbors, and so about 50% of the deaths are from those fights between packs, mostly in the winter, and they're kind of competing for resources,” Cassidy said.

Although wolves are protected from humans in Yellowstone, occasionally they are killed by a vehicle, or leave the park boundaries into hunting areas.

Remarkably, Wolf 907 has lived in Northern Yellowstone with the Junction Butte wolf pack her entire life.

“She inherited the leadership position when her aunt died, and so she has never had to disperse in her entire life. I think that probably contributed to her long life and her success because she never had to go through that period of being off by herself, finding a new mate, trying to kind of elbow out a territory in a pretty highly competitive environment like Northern Yellowstone,” Cassidy said.

Wolf 907 (gray wolf in upper center) and her Junction Butte pack.

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Courtesy Yellowstone Wolf Project

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She's networking her family

Cassidy’s research includes field work like setting up trail cameras as well as analyzing long term data on wolves.

This year, Wolf 907 chose a den that she’s used before to give birth, and researchers watched from a mile away with a spotting scope.

This isn’t the first time Cassidy and her crew have watched her bring new life to the park, and they continue to monitor the pups from her past litters as well.

“It's really interesting to see how 907, because she is so long lived, she now has a number of her offspring or a niece or a nephew that have started packs all around her,” Cassidy said. “Her son is one of the leaders of the pack to the south. Another son is a leader of the pack to the west. She has two daughters that are leading packs that are also nearby, and a niece on the east side. So she's kind of all surrounded by her offspring or close relatives.”

These relationships might encourage tolerance for Wolf 907’s pack if they encounter another pack, which is usually very dangerous, according to Cassidy.

She knows how to delegate

There are about 100 adult wolves in Yellowstone right now, and a quarter of them have radio collars that send location pins to a satellite system for the researchers to monitor. Most of the time, a collar is going to outlast a wolf’s life, Cassidy said.

Wolf 907

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Courtesy Yellowstone Wolf Project

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Wolf 907 has been captured multiple times to switch out her collar because she keeps outliving the battery life. In the 30 years since wolves have been introduced to Yellowstone, only six wolves, including 907, have reached their eleventh year. Of those, only two have made it to 12.

“If I'm just going to throw out the odds of her reaching 12 years old, it's maybe like 50-50 at this point,” Cassidy said. “She just keeps surprising me.”

According to Cassidy, the longer a wolf lives, the more knowledge and the more experiences they have, and they're critical to teaching their packmates how to be successful.

“She's not really participating in the big hunting of elk and bison anymore; she lets her younger pack mates do that. So, her chances of getting kicked and killed in a hunt are fairly low. She's kind of mitigating a lot of those really dangerous things that kill wolves, even at very young ages,” said Cassidy. “She has probably figured out how best to live in the place that she's living.”