Huge flock of migratory birds landed on acidic waters of an open pit mine where employees attempted to scare them off
Wednesday 7 December 2016 01.28 GMT
Several thousand snow geese have died after a snowstorm forced large flocks to take refuge in the acidic, metal-laden waters of an old open pit mine in Montana.
Mark Thompson, environmental affairs manager for mine company Montana Resources, said witnesses described the pit as like “700 acres of white birds” on 28 November.
Along with Atlantic Richfield, Montana Resources is responsible for Berkeley Pit in Butte.
Since 28 November, employees of MR and Arco had used spotlights, noise makers and other efforts to scare or “haze” the birds off the water and prevent others from landing.
The companies estimated that more than 90% of the birds had been chased off by 29 November, Thompson said.
Workers received some advance notice about the incoming flock from an off-duty Montana Resources employee about 25 miles away, who called to report there were about 25,000 geese in the air in Anaconda, Thompson said.
“I can’t underscore enough how many birds were in the Butte area that night,” Thompson said. “Numbers beyond anything we’ve ever experienced in our 21 years of monitoring by several orders of magnitude.”
The employees worked hard to save the birds, he said.
Typically, Butte sees between 2,000 and 5,000 birds all year, including spring and water migration, Thompson said.
The estimated death toll is based on drone and aircraft flights over the pit, which holds about 45bn gallons (175bn litres) of water.