This 12 February 2020 video from the USA says about itself:
First-ever footage of wolves eating blueberries in Northern Minnesota
The first-ever footage of wolves eating blueberries in the Greater Voyageurs Ecosystem! We tried for 2 years to get this footage of wolves eating berries and finally got it this past summer! As far as we know, this is the only footage that exists of wild wolves eating blueberries. Though, we know of a few clips of wolves eating other kinds of berries or fruits.
By Jake Buehler, 11 February 2020:
Wolves regurgitate blueberries for their pups to eat
Fruit may be more important to the animals’ diet than previously thought
Gray wolves are known to snack on blueberries, but the animals do more than fill their own bellies. A new, serendipitous observation shows an adult wolf regurgitating the berries for its pups to eat, the first time anyone has documented this behavior.
Wolves have a well-earned reputation as skillful hunters with a taste for large, hoofed ungulates like deer and moose. But scientists are increasingly recognizing that these predators have an exceptionally varied diet, partaking in everything from beavers and fish to fruit.
In 2017, biologist Austin Homkes of Northern Michigan University in Marquette got a sense of just how important this mixed diet could be for wolves. A cluster of signals from a GPS collar on a wolf led Homkes to a meadow just outside Minnesota’s Voyageurs National Park. Homkes, who was studying the animals’ predatory and dietary habits, thought he was headed for a spot where the wolf had killed a meal. But it turned out to be a rendezvous site, with adult wolves bringing food to their no longer den-bound pups.
Homkes watched from a distance as several pups gathered around an adult wolf, licking up at its mouth. This behavior stimulates adult wolves to throw up a recent meal. Sure enough, the adult began vomiting, and the pups eagerly ate what accumulated on the ground. After the wolves left, Homkes got closer and saw that the regurgitated piles were purely of partially chewed blueberries, he and colleagues report February 11 in the Wildlife Society Bulletin.
“It’s a pretty big part of wolf ecology that was right under our noses that we didn’t see,” Homkes says.
Until now, he and his colleagues thought pups in the region just casually munched on berries while hanging around rendezvous sites, which often contain blueberry plants. The fruit may be an underappreciated food source for the pups, the researchers think.
Conservation biologist Robert Mysłajek of the University of Warsaw says the discovery is an “interesting complement” to our knowledge of the species. “Such observations should be especially important for wildlife managers, who often focus only on wolf-ungulate interactions, forgetting about other food items consumed by wolves,” Mysłajek says.
The findings are generating plenty of questions. Homkes is curious about the nutritional value of blueberries for the mostly carnivorous wolves, and the consequences of a bad berry year. “What happens when blueberries are not available if a pack is used to relying on them?” he wonders.