BUTTE, Mont. (AP) — At a former open pit copper mine filled with billions of gallons of toxic water, sirens and loud pops from propane cannons echoed off the granite walls to scare away birds so they don't land.
After several thousand migrating snow geese perished in the Berkeley Pit's acidic, metal-laden waters in 2016, its owners deployed an arsenal to frighten away flocks, including lasers, drones, fireworks and remote-controlled boats.
Montana Resources already had been hazing incoming birds with spotlights and rifle shots into the water — and a spokesman said those deterrents likely helped the company avoid a penalty or prosecution under the Migratory Bird Treaty Act.
But the Trump administration wants to end the 50-year practice of using criminal penalties under the migratory bird law to pressure companies into taking measures like these to prevent unintentional bird deaths.
Critics — including top Interior Department officials from Republican and Democratic administrations — say the proposed change could devastate threatened and endangered species and accelerate a bird population decline across North America since the 1970s.
Former U.S. Fish and Wildlife Service Director Dan Ashe told The Associated Press the law's threat of prosecution served as "a brake on industry" that probably had saved billions of birds.
"Removing that obligation, if it stands, over the next several decades will result in billions of birds being casualties," said Ashe, who served in the Obama administration. "It will be catastrophic."
Industries kill an estimated 450 million to 1.1 billion birds annually, out of an overall 7.2 billion birds in North America, according to the U.S. Fish and Wildlife Service and recent studies.
The Trump administration dismissed Ashe's dire prediction, claiming companies will continue to avoid bird deaths voluntarily.
At the Berkeley Pit, Montana Resources plans to keep up efforts that drive away almost all birds, in part to avoid a repeat of the negative publicity and community backlash that followed the 2016 bird kill, according to Mark Thompson, the manager of environmental affairs.
"We as a company see it as an essential environmental protection," Thompson said.
The 1918 migratory bird act came after many U.S. bird populations had been decimated by hunting and poaching, much of it for feathers for women's hats. Over the past half-century, the law also was applied against companies that failed to prevent foreseeable bird deaths.
However, the Trump administration says deaths of birds that fly into oil pits, mining sites, telecommunications towers, wind turbines and other hazards should be treated as accidents not subject to prosecution. An Interior Department proposal would cement that into federal regulation.
State officials and wildlife advocates who are suing the administration in federal court say birds already are being harmed under actions allowed by a 2017 Trump administration legal memo that signaled the rule change.
Most notable was the destruction last fall of nesting grounds for 25,000 shorebirds in Virginia to make way for a road and tunnel project. State officials had ended conservation measures for the birds after federal officials said such measures were voluntary under the new interpretation of the law.
The move to relax the bird law, combined with Trump rollbacks of the Endangered Species Act and the National Environmental Policy Act, puts birds and their habitat at greater risk, said Audubon Society vice president Sarah Greenberger.
The Trump administration proposal follows longstanding pressure from oil companies, utilities and other industries.
The Edison Electric Institute, which represents many U.S. utilities, contends it would be "absurd" to criminalize "ordinary, everyday activities" that happen to result in a bird death, which can result in up to six months in prison and a $15,000 penalty for every bird injured or killed.