Will Iowa’s migratory birds be at risk when they head south?

Some birds that spend parts of their lives in Iowa could face new perils this fall when they migrate to or through the oil-contaminated north coast of the Gulf of Mexico.

“We're pretty worried about the fate of waterfowl, wading birds and shorebirds” that have long wintered in the Gulf's food-rich protected marshes, said Tim Yager, manager of the McGregor District of the Upper Mississippi River National Wildlife and Fish Refuge.

The concern, Yager said, is twofold - that remnant oil from the recently capped BP oil spill will directly coat their feathers or that they will eat fish and other aquatic animals contaminated by the oil.

Iowa Department of Natural Resources waterfowl biologist Al Hancock said the Gulf oil's impact on migrating birds will be greatest on scaup and redheads, two species of diving ducks that feed on crustaceans and other invertebrates in the deeper saltwater off the Gulf coast.

Ric Zarwell of Audubon Iowa said he worries that fish-eating birds that frequent the freshwater and brackish marshes near the coast also could be in harm's way. Among them, he said, are part-time Upper Mississippi residents, such as herons, egrets, cormorants, American white pelicans and common loons.

“They will be ingesting fish that could very well be contaminated with oil,” said Zarwell, of Lansing.

Zarwell said he is much less concerned about Neotropical migrant songbirds, such as warblers, thrushes, tanagers and vireos, most of which winter farther south than the Gulf.

Yager said the Gulf oil spill will have little effect on two bird species that visit the Upper Mississippi in great numbers each fall - tundra swans and canvasback ducks. After their stop on the refuge, most of them fly east and winter on Chesapeake Bay or the Atlantic coast, he said.

As of July 15, the day the flow was essentially stopped, the BP well had gushed about 4.3 million barrels of crude oil into the Gulf. A federal report last week asserted that about 75 percent of the leaked oil had been burned, emulsified, recaptured or had otherwise disappeared from view. Scientists fear that much of that oil is now hidden within the water column and still threatens birds and others parts of the natural environment.

Louisiana State University professor Al Afton, who spends part of each year studying scaup in Iowa, said he worries that a strong hurricane could push oil into the freshwater marshes ringing the Gulf, jeopardizing scores of bird species that might otherwise avoid the worst-case scenario.

Though migratory patterns are deeply ingrained, Afton said he sees promise in plans to “shortstop” ducks, geese and other migratory birds before they reach the Gulf.

The federal government is spending more than $20 million on alternative habitat on 150,000 acres in eight states, and Ducks Unlimited has received a $2.5 million grant from the National Fish and Wildlife Foundation to flood Louisiana and Texas rice fields.

Citing potential long-term effects and limited monitoring, Jon Stravers of McGregor, a bird researcher with the Audubon Mississippi River Initiative, said the extent of the disaster will not soon be known.

Iowa State University ornithologist Steve Dinsmore, one of the state's foremost bird experts, said the Gulf oil spill is uncharted territory with many variables.

“It's just too soon to tell how migratory birds will be affected,” he said.