SALMON, Idaho (Reuters) - A poison used on cropland to kill rodents also killed at least a handful of more than 2,000 snow geese that fell dead from the sky in Idaho while migrating to nesting grounds on the coast of Alaska, state wildlife officials said on Friday.
The carcasses of the snow geese were found in March in eastern Idaho, where dozens of state Department of Fish and Game workers and volunteers retrieved and incinerated most of the dead birds to avoid spreading what biologists believed to be avian cholera.
But testing by a state lab of a small number of sample carcasses indicated several of those birds died from zinc phosphide poisoning, while lab results were inconclusive for avian cholera, said Fish and Game spokesman Mike Demick.
“Avian cholera may have played a part in the die-off, but to what extent is unknown,” he said in a statement.
Zinc phosphide is a compound found in rodenticides used on cropland. Results from testing have been sent to the Idaho Department of Agriculture for further review, Demick said.
Avian cholera, a highly contagious disease that sometimes affects snow geese during their northern migrations in spring, was initially suspected because of the way the birds died, according to Fish and Game.
“Basically, they just fell out of the sky,” Gregg Losinski, conservation educator for the agency, said at the time.
Snow geese are best known for their white plumage and for breeding in the far northern corners of Alaska, Canada, Greenland and Siberia. Demick said that while the die-off was unfortunate, it would not affect overall populations of snow geese, which number in the millions.
Reporting by Laura Zuckerman in Salmon, Idaho; Editing by Cynthia Johnston and Eric Beech