Estimation of Waterfowl Food Abundance in Coastal Freshwater Marshes of Louisiana and Texas
Food abundance might limit survival or recruitment of wintering waterfowl. Nutritional requirements of wintering waterfowl have been estimated, but there are insufficient data on the abundance of seeds and submerged aquatic vegetation (SAV) to determine if enough habitat exists to support target populations of waterfowl throughout winter. I estimated waterfowl food abundance at 14 coastal freshwater marsh sites in Texas and Louisiana from August 2001 to March 2003, and tested the hypothesis that wintering waterfowl reduce food abundance. I analyzed 210 and 360 seed and SAV samples, respectively, taken during September 2001, February 2002, September 2002, and February 2003 to estimate seed and SAV biomass and determine if biomass declined during the winter. At one site, SAV biomass was estimated from 108 samples taken at six-week intervals (August-March) to provide another means of determining if food abundance declined throughout winter. Also at that site, 108 samples were taken from waterfowl exclosures in August and January of each year to provide another means of determining if wintering waterfowl reduce food abundance. Seed and SAV biomass estimates were not significantly different among time periods; biomass estimates of 14 genera of seeds and 8 genera of SAV collected averaged 244.2 ± 23.8 kg/ha (mean ± SE) and 262.3 ± 95.0 kg/ha, respectively. No significant differences in SAV biomass were detected among time periods at the six-week site or among time, treatment, and treatment by time interactions at the exclosure site. Mean food biomass estimates were well above the 50 kg/ha threshold estimate assumed to be the point of diminishing returns for feeding waterfowl. These findings also indicate that waterfowl did not significantly lower food resources in my study area over the two years of my study.
Advisor:John Andrew Nyman; Megan LaPeyre; Frank Rohwer
School:Louisiana State University in Shreveport
School Location:USA - Louisiana
Source Type:Master's Thesis
Keywords:forestry wildlife fisheries
Date of Publication:11/12/2003