Birds from Canada are ready to head south, and are in for a deadly shock when they reach still fouled Gulf Coast.
Migratory birds are heading south into the troubled shores of Louisiana.
Many areas are too contaminated to support the invertebrates migrating birds require.
Nearly five million Migratory birds from Canada are now winging their way south across North America, and many of them could be in for a nasty shock when they reach the oily marshes and beaches along the Gulf Coast.
"There's a lurking time bomb for many waterfowl and shorebirds that breed in Canada's boreal forest and winter or stop in the Gulf," said Jeff Wells, senior scientist at the Boreal Songbird Initiative.
There are several concerns ornithologists have about the birds. First of all, they could come into direct contact with oil that's present in many salt marshes, as well as just under the surface of shores and islands off Louisiana.
Then there is the problem of food. Many shorebirds eat small invertebrates that live in the sand along the shore. Now a lot of that sand is saturated with oil just below the surface, which has wiped out the invertebrates.
"The birds are actually dipping their bills down into the oil," said Wells.
The marshes, shores and islands of the Gulf Coast are a bottleneck for birds heading south, as they provide the last chance for many of these birds to fatten up before flying 500 miles across the Gulf to their wintering grounds in the Caribbean or South America. It's arguably one of the word's the worst places to have a major environmental disaster, said Melanie Driscoll, director of bird conservation for the National Audubon Society's Louisiana Coastal Initiative.
In order to see whether migrating birds get mired directly in oil, or if there are any other surprises in bird behavior or health due to the oil spill, the Audubon Society is planning on expanding teams of volunteer and professional bird watchers to monitor what happens in the coming months, and even years.
Among the first things that might be observed, said Driscoll, is a desperate search for food. If shorebirds can't find food, they will start moving around, looking for it in other areas. food
"Migrant birds have very plastic behavior," said Driscoll. "We should be able to see changes in the use of habitat."
Driscoll said she recently visited one of the barrier islands off Louisiana and confirmed Wells' concern about the oil. She found oil-saturated sand just a half inch from the surface of the sand. The oil-soaked sand went down as far as she dug, which was about 15 inches, she said. That's very bad news for shorebirds.
"We're not really sure what will happen," Driscoll told Discovery News. Birds might fail to find enough food and then not complete their migration, search much further and find food, or try to fly without eating enough, and not make it.
"To get answers, we're really looking at these long-term monitoring efforts."
It could take years to sort out the effects to migrating birds, because they are difficult to count and, by their nature, move around a lot.
In the case of the Exxon Valdez disaster, the effects to birds are still being seen because oil is still surfacing on the beaches -- 21 years later. But because the Gulf Coast is so much warmer, Driscoll and others hope that the bacterial degradation of the oil will happen faster than in Alaska's colder Prince William Sound.
"What's really going to matter is the long term impacts to this ecosystem," said Driscoll. "It's a bad place to have a really bad natural disaster."
To participate in the National Audubon Society's Gulf Coast bird monitoring, learn more here.