By Patrick Pester, published June 3, 2024

Wolf 907F recently gave birth to her 10th litter of pups, which researchers say is likely a Yellowstone National Park record.

Wolf 907F walking past a trail camera in Yellowstone National Park. (Image credit: Yellowstone Wolf and Cougar Project)

The alpha female of a Yellowstone gray-wolf pack has defied the odds by having a 10th litter of pups at the age of 11.

The one-eyed wolf elder, named Wolf 907F, gave birth to her latest litter last month, the Cowboy State Daily reported. Gray wolves (Canis lupus) have an average life span of three to four years, so it's rare for them to reach 11, let alone have pups at that age.

Wolf 907F has given birth to pups every year for a decade straight since she became sexually mature, which Kira Cassidy, a research associate at the Yellowstone Wolf Project, said is likely a record for the wolves of Yellowstone National Park.

At age 11, Yellowstone’s Wolf 907F has lived more than twice a wild wolf’s average life expectancy. In this photo from April, she was pregnant with a litter of pups that she’s since given birth to. (Courtesy Yellowstone Wildlife Project)

"Every day, I expect that she might die just because she is so elderly, but I've been thinking that for the last few years, and she keeps going," Cassidy told Live Science.

Cassidy has calculated that only about 1 in 250 wolves in Yellowstone make it to their 11th birthday, with just six recorded examples since wolves were reintroduced to the park in 1995. The oldest of all of these great elders lived to 12.5 years, according to the National Park Service.

Wolf 907F lies in the snow in Yellowstone in 2015. (Image credit: Kira Cassidy/NPS)

Wolf 907F is the oldest wolf to have lived her whole life in the park's Northern Range, where there is more prey but also more competition from other wolves. Wolves rarely die of old age in the wild, and in Yellowstone National Park, the biggest threat is other wolves.

"In a protected place like Yellowstone, their number-one cause of death is when two packs fight with each other," Cassidy said. "That accounts for about half of the mortality."

One of Yellowstone's oldest wolves, Wolf 907F is pictured here with her pack last year. She's the gray collared wolf on the lower left. (Courtesy Yellowstone Wildlife Project)

Wolf 907F is the alpha female of the Junction Butte pack, which has between 10 and 35 members at any given time. Cassidy noted that this is a large pack — the average wolf pack size is about 12 individuals — and that reduces the risk of being killed in territorial fights. Wolf 907F's experience also gives her pack an edge.

"Packs that have elderly wolves are much more successful in those pack-versus-pack conflicts because of the accumulated knowledge and the experience that they bring to that really stressful situation," Cassidy said.

Wolf 907F has likely boosted her pack's survival chances outside of battle, too. Cassidy noted that the Junction Butte pack rarely leaves Yellowstone's border and that Wolf 907F is "savvy" when it comes to things like crossing roads and avoiding humans.

Wolf 907F, Yellowstone's aging matriarch at 11 years old, only has one eye. She's the fourth wolf to pass by this trail cam. (Courtesy Yellowstone Wildlife Project)

What makes Wolf 907F even more impressive is that she does all of this with only one functioning eye. Researchers aren't sure what happened, but her left eye has been small and sunken since before she turned 4. "You would never know [when] watching her," Cassidy said.

Like other elders, Wolf 907F takes a back seat in hunts now that she's older, and she spends most of her day hanging around with the pack's pups. Cassidy and her colleagues have counted three pups in her current litter, which is smaller than the average litter size of four to five but not surprising. A 2012 study of Yellowstone wolves published in the Journal of Animal Ecology found that litter size declines with age.

"The fact that 907 is still having pups is amazing, and her litter being small is expected given that she is so old," Cassidy said.

A few of Wolf 907F's offspring now lead packs of their own, but most of her pups never reach adulthood due to the perilous nature of being a wolf. However, Wolf 907F and the others in the park don't seem to live like death is on their mind.

"They are happy to be with their family going from day to day," Cassidy said. "Even if they have injuries or are missing an eye or something really stressful is going on in their life, they move through that stress and go back to seemingly really enjoying their life."

A hydrothermal explosion happened Yellowstone!! And I’m alive to see it! I wish I was there.

From USGS Facebook:

A small hydrothermal explosion occurred in Yellowstone National Park today (July 23, 2024) around 10:00 AM MST in the Biscuit Basin thermal area, about 2.1 miles (3.5 km) northwest of Old Faithful. Numerous videos of the event were recorded by visitors. The boardwalk was damaged, but there were no reports of injury. The explosion appears to have originated near Black Diamond Pool.

Biscuit Basin, including the parking lot and boardwalks, are temporary closed for visitor safety. The Grand Loop road remains open. Yellowstone National Park geologists are investigating the event.

Hydrothermal explosions occur when water suddenly flashes to steam underground, and they are relatively common in Yellowstone. For example, Porkchop Geyser, in Norris Geyser Basin, experienced an explosion in 1989, and a small event in Norris Geyser Basin was recorded by monitoring equipment on April 15, 2024. An explosion similar to that of today also occurred in Biscuit Basin on May 17, 2009.

More information about hydrothermal explosions is available at https://www.usgs.gov/observatories/yvo/news/hydrothermal-explosions-yellowstone-national-park.

Monitoring data show no changes in the Yellowstone region. Today’s explosion does not reflect activity within volcanic system, which remains at normal background levels of activity. Hydrothermal explosions like that of today are not a sign of impending volcanic eruptions, and they are not caused by magma rising towards the surface.

Additional information will be provided as it becomes available.

The Yellowstone Volcano Observatory (YVO) provides long-term monitoring of volcanic and earthquake activity in the Yellowstone National Park region. Yellowstone is the site of the largest and most diverse collection of natural thermal features in the world and the first National Park. YVO is one of the five USGS Volcano Observatories that monitor volcanoes within the United States for science and public safety.

YVO Member agencies: USGS, Yellowstone National Park, University of Utah, University of Wyoming, Montana State University, UNAVCO, Inc., Wyoming State Geological Survey, Montana Bureau of Mines and Geology, Idaho Geological Survey

"Two weeks ago [mid-June, 2024], Yellowstone National Park made headlines when a mother grizzly bear was spotted out and about with five cubs in tow — the biggest grizzly bear cub litter ever seen in the park. 

Grizzly bears in that region of North America typically only have one to three bear cubs a litter. 

Frank van Manen, the leader of the Interagency Grizzly Bear Study Team, said it was possible that an “adoption” event had occurred, in which two mothers give birth in the same year, and one ends up taking on the sibling’s cubs. 

In an interview, van Manen told Wyofile that if the bears had all been born in the same litter, it would be the first five-cub litter “recorded in the history of the Greater Yellowstone Ecosystem.”

“Whether it was an adoption or whether it truly is a five-cub litter, it just amazes me that every year there’s some new surprise to us, even after intensively studying this population for more than 50 years,” van Manen said. “I just think that’s cool.” ...

On top of this record sighting, [Grizzly watch Bill] Hamblin is baffled by the sheer number of cubs that have been spotted so far in 2024. 

Since they started emerging in the spring, the total count of unique grizzly bear cubs spotted has ticked up to a whopping 18 — triple the average number. 

“That’s more than we’ve ever seen,” Hamblin said."