Gulf Coast marshes losing ability to support waterfowl, study says

GCJV study reveals significant waterfowl food deficits

LAFAYETTE, La. – June 10, 2010 – Gulf Coast Joint Venture (GCJV) scientists recently completed analyses demonstrating that the massive losses of coastal wetlands during the past half-century have reduced the capacity of Gulf Coast marshes to support wintering waterfowl. Potential impacts of the Deepwater Horizon oil spill to marsh vegetation and food production mean waterfowl may encounter even greater food shortages when they arrive on the Gulf Coast later this year.

GCJV study map
Click on the image to enlarge The shaded area of this map represents the area covered in the study, as well as the Gulf Coast Joint Venture's overall coverage area.

"We've known for years that coastal habitat loss and degradation have been slowly reducing the Gulf Coast's capacity to support wintering waterfowl," said Dr. Mike Brasher, GCJV biological team leader. "However, no study had quantified the consequences of coastal marsh loss to waterfowl food availability."

This study estimated the amount of habitat required to support winter waterfowl population objectives and compared that to the available habitat. "Basically, we asked how many acres of marsh it takes to feed a desired number of waterfowl, then compared that to what is presently on the landscape," said Dr. Brasher.

The study area included coastal marshes from Mobile Bay, Ala., to Corpus Christi, Texas. Scientists used a measure called duck-energy-days (the dietary energy needed to sustain a single duck for a single day) to estimate how much food would be required to support population goals set forth by the North American Waterfowl Management Plan. Their calculations revealed that under the assumption of a 150-day winter period, coastal marshes in these areas satisfy energy demands of 2.9 million fewer ducks and geese than what they likely did during the 1970s. In southeast Louisiana alone, coastal marsh food resources may support 1.3 million fewer waterfowl than what is targeted by GCJV population objectives.

"Completion of this work represents a significant step in developing quantitative coastal marsh restoration objectives for waterfowl. But the sobering fact is that these results suggest Gulf Coast marshes may presently be unable to support historic populations of wintering waterfowl. As tragic and potentially harmful as the Deepwater Horizon oil spill is, I think the important thing to remember is that these marshes were under siege long before the spill, and there is every indication that those same forces will continue to threaten them long after the spill," said Dr. Brasher.

"GCJV partners recognize coastal marsh conservation as a high priority throughout this region," said Dr. Tom Moorman, DU director of conservation programs for the Southern Region. "We believe significant progress toward reversing and eliminating waterfowl foraging deficits will require large-scale restoration projects such as river diversions and sediment delivery projects."

Projects of that magnitude are in the hands of state and federal entities. In the meantime, conservation partners continue to strategically deliver local-scale restoration and enhancement projects to minimize further declines in waterfowl carrying capacities, and they hope oil will stay out of the interior freshwater and intermediate marshes which are so important to waterfowl.

Joint ventures are regionally based, biologically driven, landscape-oriented volunteer partnerships of private, state and federal conservation organizations dedicated to the delivery of habitat conservation important to priority bird species. The GCJV spans the coastal portions of Alabama, Mississippi, Louisiana and Texas. Its mission is to advance the conservation of important bird habitats within the GCJV region.

Ducks Unlimited is the world's largest non-profit organization dedicated to conserving North America's continually disappearing waterfowl habitats. Established in 1937, Ducks Unlimited has conserved more than 12 million acres thanks to contributions from more than a million supporters across the continent. Guided by science and dedicated to program efficiency, DU works toward the vision of wetlands sufficient to fill the skies with waterfowl today, tomorrow and forever.

Andi Cooper
601.956.1936
acooper@ducks.org