Raising a litter of teething wolf pups is no easy feat, but the wolves living in Yellowstone National Park are parenting pros. This spring, the park’s biologists captured video footage of adult wolves repeatedly returning to their den with so-called “toys”—in the form of antlers, bones and sticks—to keep their little ones happy between meals.
The video, which the park posted on social media last week, is a compilation of shots captured by a trail camera. It shows a series of solo adult gray wolves (Canis lupus) trotting through a forested area with “some interesting items” in their mouths, per the park.
Once they wean off their mother’s milk, wolf pups rely on adults to go out and hunt, then bring back food to the den. But when that’s not possible, the adults instead retrieve odd items for the pups to gnaw on.
“Pups await food deliveries from successful hunts, but in the absence of food, adults bring ‘toys,’” the park wrote on Facebook. “The instinct to bring items back to the den may be reinforced by evolution and probably helps keep adults from being mobbed by sharp puppy teeth.”
The adult wolves are part of “Mollie’s Pack,” one of ten known wolf packs living within Yellowstone as of January 2023. This particular pack is named after Mollie Beattie, who in 1993 became the first woman to serve as director of the United States Fish and Wildlife Service.
Beattie, who died in 1996 at the age of 49, advocated for the reintroduction of wolves into Yellowstone National Park to help rebalance the ecosystem after the animals were systematically exterminated within the park and the lower 48 states through the mid-1900s. Wolf reintroduction was a highly controversial initiative that many people—especially local farmers and ranchers—opposed. And yet, Beattie and other wildlife managers ultimately achieved their vision and successfully relocated 41 wolves from western Canada to the park between 1995 and 1997.
Today, that number has blossomed to at least 108 wolves living in Yellowstone. Additional wolves live outside the park, too, in what’s known as the Greater Yellowstone Ecosystem. The population is largely healthy, though the Yellowstone wolves have suffered from diseases like distemper and a skin infection known as sarcoptic mange, which is transmitted by mites.
Wolves usually live between two and five years, however, one Yellowstone wolf made it to 12.5 years old, per the park. They primarily eat elk, deer and smaller mammals, though they are also increasingly feeding on bison.
The mammals typically mate in February, and after a gestation period of roughly 63 days, females give birth in dens by mid-April. The average litter size is four to five pups, which subsist on their mother’s milk for the first five to nine weeks of their lives. After they wean, adults continue to feed them for another three months by eating and regurgitating prey.
Today, gray wolves are protected under the Endangered Species Act in many states. In late 2020, the Trump administration removed the animals from the endangered list, which eliminated their legal protections. But in February 2022, they were re-listed as endangered after a judge reversed the decision.
Outside of Yellowstone, wolves have been reintroduced elsewhere in the U.S. In 2020, Colorado voters narrowly approved a plan to reintroduce wolves to the state. Wildlife officials say they will begin releasing the animals by the end of this year, though they have been having a tough time finding another state that will donate wolves to the cause.
At Michigan’s Isle Royale National Park, biologists released wolves relocated from the state’s Upper Peninsula, Minnesota and Canada in 2018, in hopes that they would repopulate the island. At the time, just two highly inbred wolves remained; now, the park’s population has grown to 31 wolves.
Editor’s Note, August 29, 2023: This story has been updated to reflect that Mollie Beattie became director of the Fish and Wildlife Service in 1993.