Survival and Habitat Use of Female Gadwalls Along the Gulf Coast
Over 75 percent of North America’s gadwall population winters along the Louisiana and Texas Gulf Coasts. Gadwalls frequent the coastal marshes in these states and typically rank first or second among all duck species in terms of number harvested. Despite their significance to hunters in this region, waterfowl biologists have a relatively poor understanding of gadwall habitat use, regional and long-range movements, and over-winter survival rates. Gadwalls spend extensive time feeding during the winter, hence habitat quality and quantity and disturbance maybe important factors influencing choice of wintering areas, regional movements, and over-winter survival rates.
Consequently, the Gulf Coast Joint Venture (GCJV), Ducks Unlimited (DU), Texas Parks and Wildlife Department, Louisiana Department of Wildlife and Fisheries and Louisiana State University have initiated a cooperative research effort to better understand winter movements and survival of gadwall. A pilot research study was conducted during fall and winter 2006-2007 to assist with the development of a full-scale study during 2007 – 2009. Researchers equipped 16 female gadwalls with backpack mounted satellite transmitters and tracked them throughout the winter and subsequent spring migration.
Researchers recently launched the full-scale study, but used data collected during the pilot study to slightly modify study methods. Most notable was a decision to use implant satellite transmitters (i.e., transmitters are physically implanted into the abdominal cavity of captured female gadwalls) rather than backpack style transmitters, because backpack transmitters appeared to have higher than desired adverse impacts on survival rates of the radiomarked gadwalls.
Results of this research will be used to evaluate current GCJV conservation strategies that focus on restoring habitats to attract and support wintering gadwalls.
For further information, please see the following links:
Investigators:
Michael Brasher, Biological Team Leader, Gulf Coast Joint Venture
Barry Wilson, Coordinator, Gulf Coast Joint Venture
Al Afton, USGS – LA Cooperative Fish and Wildlife Research, Louisiana State Univ.
Chad Manlove, Director of Development, Ducks Unlimited, Inc.
Robert Helm, Waterfowl Coordinator, Louisiana Dept. of Wildlife and Fisheries
Dave Morrison, Waterfowl Program Leader, Texas Parks and Wildlife Department