Countless birds make an annual fall migration from Canada to South America, stopping to rest and refuel in the marshes and barrier islands of the Gulf Coast. This year, ornithologists are understandably concerned. The birds spend a lot of time in the Gulf, often fattening up on invertebrates. But as Discovery News reports, this year they are in for a big surprise. While BP may have sealed the oil spill, the presence of oil in the surrounding ecosystem will shape the bird’s existence for years to come.

Jeff Wells is an ornithologist tracking the birds. As he told Discovery News, "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.” The birds will come in direct contact with oil, which is still present in the marshes. Their food sources have also been markedly influenced by the crude, either by poisoning or by dying out completely.

Experts say the invertebrates that make up most of the bird’s diet have been killed off from the spill. The incoming birds have made their home in the sand, which is now saturated in oil. Worse, the birds are dipping their bills directly into the oil to search for food. Authorities have dug deep into the sand by as much as 15 inches, and they have found oil all the way through.

The consequences of this are still largely unknown. Melanie Driscoll is director of bird conservation for the National Audubon Society's Louisiana Coastal Initiative. As she told Discovery News, "We're not really sure what will happen. 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.”

One solution experts are proposing is to try to divert the birds from the oiled beaches. The federal Fish and Wildlife Service has put forth a $20 million effort to pay farmers in Southern states to flood their farmlands. Hopes are this will create new wetlands that might appeal to the birds over the oiled marshes. And while some critics say that birds typically return to the same spots year after year, others hope that they will abandon old spots once they find them devoid of food.

Ultimately, organizations like the Audubon Society plan to monitor the birds to determine the long-term effects of the spill on wildlife.

For further reading:

Millions of birds flock to the Gulf Coast for annual migration
Experts say the roughly 5 million birds currently flying south from Canada are in for a crude awakening in the Gulf.