Officials know what’s killing Portland sea gulls, but not others across Maine

Around the time 45 seagulls turned up dead in Deering Oaks Park, the Department of Inland Fisheries and Wildlife responded to “about a half dozen” reports of dead gulls throughout Maine. But those deaths don’t seem to have a uniform cause, a department official said.

Some of the Portland carcasses were sent to a federal lab in Wisconsin for testing, where scientists determined that they were infected with a bird-borne strain of cholera.

But tests of other gulls found dead in Rockland, Augusta and Gardiner did not come back positive for the bacteria, said IFW bird specialist Brad Allen.

Avian cholera is “highly infectious” and “not an uncommon disease in migratory birds,” Allen said. But the department believes that the outbreak was limited to the flock in Portland and that the other dead gulls are unrelated, he added.

“Some of these birds were tested and cholera bacteria were not present, so we believe the mortality event was confined to the public park and pond in Portland,” he said.

Humans are not at high risk of catching bird cholera, according to the National Wildlife Health Center, and Allen said that the infection appears not to have spread to other species of birds. Bacterial outbreaks, like cholera, often infect young or weakened populations of birds, Wildlife Division director Judy Camuso previously told BDN Portland.

No new dead gulls have been found in Deering Oaks Park recently, Allen said last week.