Last week in Montana, tens of thousands of geese headed south for the winter were forced to land because of a snowstorm.
They had to quickly find the nearest source of open water, and unfortunately, that was a toxic pit of water from an old copper mine, according to Mashable.
They died soon after they reached the pit, which holds about 45 billion gallons of highly acidic water, according to Montana Resources.
Mark Thompson, the environmental affairs manager for Montana Resources, told the Associated Press that the area looked like 700 acres of white birds."
"I can't underscore enough how many birds were in the Butte area that night," Thompson told the AP. "Numbers beyond anything we've ever experienced in our 21 years of monitoring by several orders of magnitude."
He said up to 10,000 geese landed in the contaminated water that night, and the area usually only sees between 2,000 and 5,000 geese all year during both spring and winter migrations.
Environmental experts in Montana added that climate change likely played a role in the increased number of birds in the area.
Since Montana has had milder winters than usual recently, many birds are migrating later than usual, as Steve Hoffman, executive director of the Montana Audubon Society,told the Montana Standard.
Thompson told the AP that the geese's death toll would have been higher if they didn't try to scare the birds away from the pit.
Employees of Montana Resources and the Atlantic Richfield Co., which helps manage the site, worked around the clock to spook the birds away.
They used spotlights, noise makers and other tools to scare the birds away from the pit.
Nearly 90 percent of the geese had fled by the next morning.
Montana Resources and Arco estimated that several thousand birds died -- making this the largest incident near the pit in recent history.
Companies won't release the official death toll until federal and state agencies can confirm the number, the AP said.