Colorado avian flu spreads to a black bear and mountain lion, raising fears of broader reach  |

Colorado avian flu spreads to a black bear and mountain lion, raising fears of broader reach 

The bird disease has wiped out millions of domestic chickens and thousands of wild waterfowl, but is now crossing over into other animals.

Michael Booth
The Colorado Sun
A female adult northern harrier feeds on one of at least five dead birds found on the ice at Stearns Lake near Broomfield on Jan. 4, 2023. It's not clear if these dead birds had avian flu, but scenes like these and the potential for spreading the devastating virus are playing out across Colorado, wildlife officials and raptor watchers warn.
Dana Bove, Front Range Eagle Studies/Special to the Colorado Sun

Colorado’s worst-ever avian flu outbreak has crossed over into more mammals, including a black bear put down in Huerfano County and a mountain lion found dead in Gunnison County, state wildlife officials said Thursday. 

While the number of mammal cases of the bird-spread flu remains low, Colorado Parks and Wildlife said, the recent deaths confirm national warnings that the massive current outbreak will have an impact beyond domestic chickens and wild waterfowl. 

More than 6 million chickens have been killed on commercial egg farms in Colorado during the latest outbreak, which accelerated in the spring and fall of 2022. Thousands more wild birds have been killed by the fast-working disease, including large flocks of snow and Canada geese near Eastern Plains reservoirs. A handful of raptors have also been felled by the disease, including bald eagles, which total only a few hundred nesting pairs across Colorado.

Wildlife officials and researchers believe the mammals usually come in contact with avian flu by feeding on bird carcasses. A few cases have been reported in smaller mammals, and there are worries in other states that mink farms will further spread the disease. 

Crossover to humans for the current strain of avian flu so far is extremely rare, with one case in Colorado from a worker in close contact with large chicken populations. 

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“CPW continues to stress the importance of keeping your distance from wildlife, and specifically not handling sick or dead birds. Although rare, some HPAI strains can infect people,” a state news release said. “The main protection for the general public is to avoid handling sick or dead birds and keep your distance from wildlife.”

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