Yellowstone Wolf Pup Numbers Fall to a New Low Since Reintroduction, with a Possible Link to Canine Distemper
The population of gray wolves in Wyoming has declined to its lowest level since their reintroduction 30 years ago, largely due to an outbreak of canine distemper. The disease has significantly impacted wolf pups, with survival rates dropping to around 37 percent. Wildlife officials are monitoring the situation and developing management plans to support healthy wolf populations in the region.
- ▪Canine distemper has affected wolf pups in Yellowstone, leading to low reproduction rates.
- ▪In 2025, 64.3 percent of captured wolves tested positive for distemper, much higher than predicted.
- ▪Only 31 to 34 out of at least 87 wolf pups born in 2025 survived, indicating a survival rate of about 37 percent.
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Since the reintroduction of gray wolves in Wyoming — both inside and outside of Yellowstone National Park — about 30 years ago, this species has faced one battle after another, including public opposition, trapping, and poaching. But disease has also played a role in some of the struggles wolves have faced in these areas. Per the Wyoming Game and Fish’s 2025 wolf monitoring report, canine distemper significantly affected wolf pups in the park, leading to low reproduction and a population decline to its lowest level since the wolves were reintroduced.This isn’t the first time these wolves have faced this disease, and it likely won’t be the last. Here’s how it will likely impact them. Canine Distemper in Wyoming’s Wolves Canine distemper can be very unpredictable.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Discover Magazine.