Continued: Wild bird die-off probably not caused by humans

Human activity is probably not to blame for the deaths of hundreds of double-crested cormorants, a few dozen American white pelicans and a few other water birds that were discovered at two lakes in Minnesota, a leading state expert said Tuesday.

The discoveries were made last week by state Department of Natural Resources (DNR) staff members who were banding pelicans at Minnesota Lake in Faribault County, in southern Minnesota, and Pigeon Lake in Meeker County, west of the Twin Cities.

Initial tests for avian influenza were negative, the DNR said. The specific cause of the bird illness remains undetermined.

"I would doubt that it's human-related" activity that is behind the die-off, said Michelle Carstensen, DNR Wildlife Health Program coordinator, suggesting that it's "probably a pathogen [a disease-causing organism] ... very specific to that species" that is at work. As for which pathogen is to blame, Carstensen said, "It's a big list of possibilities."

Regarding the total number of birds lost, Carstensen described it as "not a big loss population-wise."

The stricken birds were found on islands where pelicans, herons, egrets and gulls traditionally nest. As of Friday, 687 cormorants and 37 pelicans, three ring-billed gulls and one great blue heron had been found dead.

Jeff DiMatteo, a DNR wildlife biologist, said staff members at Pigeon Lake "saw dead and dying adult cormorants, with the live ones unable to hold their heads up. There were old carcasses that would suggest that it has been going on for at least a couple of weeks."

Officials from the DNR, U.S. Department of Agriculture and U.S. Fish and Wildlife Service are conducting site cleanups and collecting samples for lab analysis. Some early lab results should be available this week, although it might take longer to determine the exact cause of the bird illness, the DNR said.

The die-off so far has been detected only in wild water birds at the two locations, which are about 100 miles apart, but it can be a potential source of disease when the birds come in contact with domestic poultry. Therefore, state animal health officials are reminding farmers to monitor their poultry for signs of illness and to take steps to prevent wild birds from having contact with their domestic birds.

Paul Walsh • 612-673-4482