Oil has potential to impact wintering ducks food source in Louisiana [w/Video]

12-02-2010 // Craig Guillot

As duck season gets into full swing in Louisiana, many hunters are wondering exactly what impacts the Gulf oil disaster will have on the waterfowl. While the risks of direct oiling to birds has now been diminished, experts believe wintering birds may find problems with their food source. That can affect not just Louisiana's legendary duck hunting, but entire bird populations that hail from as far north as Canada.

Louisiana’s duck harvest migrates mainly from the Prairie Porthole Region and typically arrives in the area in November. According to the Louisiana Department of Wildlife and Fisheries, an average of 2 million ducks winter off the coast of the state. Species include Gadwall, Bluewings, Greenwings, Pintails, and Blue and Green-winged teal. The birds winter throughout southeastern and southwestern Louisiana, from the marshes of Delacroix to the barren coast of Cameron Parish.

Since the start of the Gulf oil disaster, biologists have feared what would happen when wintering birds made their way down to the affected areas. Birds are especially vulnerable from direct contact with oil because oiled feathers can degrade their ability to fly and maintain their body temperatures. And when a bird preens itself to remove the oil it then ingests the toxins. While some areas of Louisiana still have fair amounts of oil NWF Senior Scientist Doug Inkley said the real threat is whether or not the food chain has been impacted.

“The real issue is whether or not the oil killed the aquatic organisms living on the bottom of Gulf in the shallow waters consumed by the divers that go down there and feed by the hundreds of thousands,” said Inkley.

Bob Dew, Manager of Conservation Programs in Louisiana for Ducks Unlimited, is concerned that oil or dispersants may have affected some of the small clam species and physid snails that many wintering ducks feed on. If that food source is not there, the ducks will likely go elsewhere. If the filter-feeding critters have absorbed the toxins, Dew is worried it could result in long-term sub-lethal impacts.

"If there's a toxic food source, the birds will ingest if and may have some physiological impacts on them that will have to be monitored," said Dew.

Polycyclic aromatic hydrocarbons (PAHs) could have an impact on food sources for years to come. And as oil lingers in some marsh areas, it also has the potential to destroy the grasses and reeds that hold together the precious duck habitat. In some places, ducks will likely come in contact with oil: Pass-a-Loutre Wildlife Refuge, one of the hardest hit areas during the Gulf oil disaster, also hosts one of the biggest wintering populations of migratory waterfowl.

Times-Picayune reporter and avid outdoorsman Bob Marshall said that the impacts will likely not be known until the end of the year and until more testing has been completed on resident birds. The Louisiana Department of Wildlife and Fisheries is currently testing tissue samples from model ducks.

"The long term risks are from these PAHs accumulating in levels high enough to be collected in these birds. We're just not going to know that for a while," said Marshall.

At the height of the spill when there was risk of heavier oiling of Louisiana's marshes and coast, Ducks Unlimited joined forces with the U.S. Fish and Wildlife Service and the Natural Resources Conservation Service to set up alternative habitats. Crop fields in other parts of the state away from the coast were flooded under the Migratory Bird Habitat Initiative. That gave birds "options" and other places to go should marshes become heavily oiled, uninhabitable wintering locations. Ducks Unlimited worked with local landowners to enroll over 75,000 acres in the program.

"We wanted to work as close to the potentially affected area to give them options should oiling occur. Fortunately there was not [catastrophic] oiling in the marsh but we still have the habitat on the ground and the response has been phenomenal," said Dew.

Marshall said that while the oil is of a concern to wintering waterfowl, a more pressing problem is the state's battle with coastal erosion. Louisiana loses roughly 25 square miles of wetlands every year.

"The oil is a temporary problem on top of a permanent disaster. The real reason duck hunting is declining in quality here is because the state is loosing habitat to the Gulf of Mexico. In 40 years, this coast may not even be here," said Marshall.

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