Tests show bird flu caused the death of a 21-year-old harbor seal at a zoo in New Bedford, Massachusetts earlier this month. The Buttonwood Park Zoo said in a social media post that the "beloved" seal named Blue likely got the avian flu by coming into contact with an infected wild bird.

Blue, a 21-year-old harbor seal, is believed to have contracted the virus through contact with a wild bird, zoo officials said.

Bird flu has killed at least four snowy owls in Massachusetts in recent weeks, adding the graceful white and black-patterned predators to its victims as it sweeps through the wild bird population.