Thousands of snow geese mysteriously dropped dead in Idaho during their annual migration, wildlife managers said Monday, and experts are trying to figure out why.

Dozens of workers and volunteers with the Idaho Department of Fish and Game spent the weekend retrieving and incinerating an estimated 2,000 geese carcasses, which were found near bodies of water as well as in a wildlife management area in eastern Idaho.

Based on the circumstances of this bizarre incident, biologists suspect avian cholera is to blame.

"Basically, they just fell out of the sky," agency spokesman Gregg Losinski told Reuters.

According to Losinski, biologists are still awaiting results from a state wildlife lab to confirm their suspicions. The highly contagious disease - which isn't a threat to humans - is caused by bacteria that can survive in soil and water for up to four months.

It is unclear exactly how the snow geese contracted avian cholera while flying to their nesting grounds on the northern coast of Alaska; however, about 20 bald eagles were seen in the areas where they fell out of the sky. It's possible the eagles were infected and transferred the bacteria to the unsuspecting snow geese.

While this situation may seem unusual, it's not uncommon. Outbreaks like this one occur every so often in the United States and elsewhere, Losinski said.

According to The Inquisitr, in the first three months of 2012 more than 10,000 migrating birds died of avian cholera in southern Oregon and northern California due to low water levels in the wetlands of a popular bird resting area.

Snow geese (Chen caerulescens) are known for their white plumage - and for breeding in the far northern corners of Alaska, Canada, Greenland and Siberia - but many of them are actually darker, gray-brown birds known as blue geese, notes National Geographic. These birds were once thought to be two separate species, but recently it has been revealed that they are one in the same, with a single gene explaining the color difference.

Populations of snow geese were reduced to only about 2,000-3,000 in the early 1900s due to hunting, but thanks to conservation efforts they have made a full recovery.

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