MIAMI – During the 10 weeks that crude oil has been gushing into the Gulf of Mexico, more than 2,000 pelicans, cormorants, gannets and water birds have been plucked from slicks and blackened shorelines — about 60 percent of them already dead.

Those numbers could soar, starting as early as this weekend. In the coming months, birds begin migrating from as far north as the Arctic into the coastal marshes, estuaries and beaches. For many, the seasonal rest and refueling stop could wind up a deathtrap.

Federal wildlife managers and scientists are devising plans to create new, unfouled havens by flooding idle farm fields and taking other measures. But they acknowledge there is only so much they can do to distract birds from danger zones along the 120 miles of coastline from Louisiana to Florida already contaminated by oil.

“We won’t be able to dramatically affect migration in any way, shape or form,” said Paul Schmidt, assistant director for migratory birds for the U.S. Fish and Wildlife Service. “The birds are still going to do what they do in the natural cycle.”

Wildlife managers, he said, expect the sort of massive mortality figures normally associated with disease outbreaks or natural disasters like wildfires or hurricanes.

Ornithologist Greg Butcher, director of bird conservation for the National Audubon Society, believes the official avian victim tally already falls far short of what has really happened and will only get worse. Some 300 species will pass through the gulf in the next six months, most in pathways that birders call the Mississippi Flyway.

“It’s really a billion birds,” said Butcher.