WASHINGTON â Exxon Mobil Corp. pleaded guilty to killing migratory birds in five states, and will pay about $7,000 for each bird killed, Justice Department officials said Thursday. ExxonMobil pleaded guilty to causing the deaths of approximately 85 migratory birds, most of which died after exposure to natural gas well reserve pits and waste water storage facilities. Birds died in Colorado, Wyoming, Kansas, Oklahoma and Texas between 2004 and 2009. Officials said that at those sites, birds would either get coated in hydrocarbons or ingest the oily waste, leading to their deaths. None of the birds are on the government's list of endangered or threatened species. The firm will pay $600,000 in a fine and payments to wetlands preservation funds. That is roughly equal to what ExxonMobil makes every 20 minutes, based on their $8.6 billion earnings for the first half of 2009. ExxonMobil has also agreed to make changes to prevent such bird deaths in the future, and says it has already spent $2.5 million in the effort. Assistant Attorney General John Cruden praised ExxonMobil for taking steps to fix the bird-killing contamination even before formally pleading guilty to five misdemeanor charges of violating the Migratory Bird Treaty Act. "ExxonMobil has worked with us and we commend them for that," said Cruden. Company spokeswoman Margaret Ross said ExxonMobil has "a long-standing water-bird protection program that focuses on deterring birds from landing in water on company property."