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Lights left on during a foggy night last year at a West Virginia wind farm are thought to be behind the grizzly deaths of nearly 500 songbirds.

It was the third time it happened -- and each time, the federal government looked the other way.

Fast forward to last week. Following the deaths of a dozen migratory birds in Montana, Wyoming and Nebraska several years back, a Denver-based oil company was fined $22,500. The company was also ordered to make an additional $7,500 payment to the National Fish and Wildlife Foundation.

The disconnect demonstrates what critics call a blatant double standard that has to change. While the federal government aggressively pursues oil and gas companies for wildlife deaths, it often gives wind producers a pass.

Proponents say going soft on the wind industry allows it to compete. But environmentalists say, in this instance, it’s unacceptable.

“The playing field is not leveled,” American Bird Conservancy spokesman Bill Johns told FoxNews.com, recalling the West Virginia incident. “If there had been a serious consequence the first time, there wouldn’t have been a second time and a third time. All they do now is go, ‘Whoops, my bad’ and it’s forgiven.”

The most recent mass bird kill in West Virginia didn’t involve collisions with wind turbines at the sprawling 61-tower complex but instead resulted from a combination of exhaustion and collisions with the substation as the Connecticut warblers, yellow-billed cuckoos and Virginia rails got trapped in the light’s glare and circled in mass confusion before dying.

The ABC is among a growing group that believes the government is playing favorites and does not hold the wind industry to the same standards as other energy generators.

The wind sector has had an exemption from prosecution under two of America’s oldest wildlife-protection laws: the Migratory Bird Treaty Act and the Eagle Protection Act. A violation of either law could result in a fine up to $250,000 or two years imprisonment. To date, the Obama administration -- following in the footsteps of the George W. Bush administration – has not prosecuted a single case against the wind industry. What they have done is gone after oil and natural gas providers for similar infractions.

“How does an industry kill more than 2,000 eagles and not be fined once?” Johns said. “It’s a head scratcher.”

A few months ago, the Justice Department brought charges against Oklahoma oil company Continental Resources as well as six others in North Dakota for causing the death of 28 migratory birds in violation of the Bird Treaty Act.

Continental CEO Harold Hamm called the move “completely discriminatory.”

Continental was accused of killing one bird “the size of a sparrow” in its oil pits. “It’s not even a rare bird. There’re jillions of them,” Hamm said during an interview with The Wall Street Journal.

Yet in central California, 70 golden eagles were killed by wind turbines at Altamont Pass, without prosecution. The findings follow a 2008 study by the Fish and Wildlife Service that estimates wind farms kill nearly a half million birds per year in the United States. The department has since backed off from that number but requests for clarification by FoxNews.com were not returned.

“They are thumbing their noses at the environmental mess they are making,” Johns said.

A study funded by the Alameda County Community Development Agency estimated that 10,000 birds – almost all that are protected by the migratory bird act – are being killed every year at the wind farm in Altamont Pass, Calif.

“The Altamont Pass wind farm does not face the same threat of prosecution, even though the bird kills at Altamont have been repeatedly documented by biologists since the mid-1990s,” Robert Bryce, a senior fellow at the Manhattan Institute’s Center for Energy Policy and the Environment, said.

“Biologists believe Altamont, which uses older turbine technology, may be the worst example. But that said, the carnage there likely represents only a fraction of the number of birds killed by windmills,” Bryce told FoxNews.com.

In 2009, ExxonMobil pleaded guilty in federal court to killing 85 birds that came into contact with crude oil and other pollutants in uncovered tanks and wastewater facilities on its property. The birds were protected by the federal act and the company agreed to pay $600,000 in fines. Over the past decade, federal officials have brought hundreds of similar cases against big energy companies operating across the country.

Oregon-based electric company PacifiCorp was ordered to pay $1.4 million in fines for killing 232 eagles that were electrocuted by power lines in Wyoming.

In March, the U.S. Fish and Wildlife Service released new guidelines for land-based wind developers trying to avoid or minimize impacts to birds and their habitat. But bird advocates say it’s an empty gesture because the guidelines are voluntary and wind farms are not required to follow them.

The backlash against the wind industry is spreading to issues across other parts of the country.

In October, 60 residents of Hermiker County in upstate New York sued the owners and developers of a 37-turbine wind farm. They claim the turbines are bigger and noisier than developers had promised and say the farm is decreasing property values in the area and causing health problems.

Noise from the property has at times clocked in above 72 decibels, 22 decibels more than local law allows. Iberdrola Renewables owns the project and has installed some noise-reduction equipment on a handful of turbines but not on all of them.

Complicating matters with the wind industry are the ongoing negotiations with the Obama administration and House Speaker John Boehner over spending cuts, tax increases and other ways to avert the looming fiscal crisis.

The wind industry has benefited from a tax credit that some say rigs the energy market. Whether to continue the tax credit, which is set to expire on Dec. 31, has become a bargaining chip in D.C.

The credit was created 20 years ago to help wind compete with other sources of electricity generation such as coal, hydropower and natural gas. The wind industry says it still needs help from the taxpayer and warns thousands of jobs could be in jeopardy if the credit is allowed to expire. Supporters bill wind generation as a clean energy that doesn’t tap into water supplies and warn that letting the credit expire would mean a death sentence for the industry.

Critics say it’s time for the industry to stand on its own or call it quits -- having benefited not only from the production tax credit but a de facto grant of immunity from federal prosecution under some of the country’s oldest wildlife laws.