Mottled Duck Habitat Use and Density Indices in Agricultural Lands

Abstract

We established indices of mottled duck (Anas fulvigula) diurnal habitat use and densities in the agricultural areas of southwestern Louisiana during 9 aerial surveys, May 1984-April 1985. We identified 15 habitats on the area. Habitat composition of transects varied among months. We observed fewest ducks and smallest flocks (ducks observed/observation) in June, highest counts of ducks in August, and largest flocks in July. Flock size was greatest in July on ponds. Habitats used most frequently were fresh marsh, rice, and flooded harvested fields. Density indices stratified by habitats differed (P < 0.05) among surveys and varied from 0.23 ? 0.04 (SE)/km2 during June to 2.65 ? 1.23/km2 during August. The most precise density indices of mottled ducks were made during March, April, and June surveys. J. WILDL. MANAGE. 53(1):110-114 Mottled ducks historically resided in the coastal marshes adjacent to the Gulf of Mexico (Sincock et al. 1964). Within the last 2 centuries, over 90% of the native prairie land adjacent to the coastal marshes of southwestern Louisiana and eastern Texas has been converted to agricultural land. Numbers of mottled duck may be declining in Louisiana, Texas (Stutzenbaker 1985), and Florida (Johnson et al. 1984). Mottled ducks breed in this area (Stutzenbaker 1985), but breeding densities have not been determined and no information is available on habitats used by mottled ducks in agricultural land. Our objectives were to determine indices of habitat use and densities for mottled ducks in the agricultural area of southwestern Louisiana. Research was conducted under the auspices of the Louisiana Cooperative Fish and Wildlife Research Unit: the Louisiana Department of Wildlife and Fisheries, U.S. Fish and Wildlife Service, Louisiana State University, and Wildlife Management Institute cooperate with the Louisiana Cooperative Fish and Wildlife Research Unit. We thank J. R. Nassar and D. C. Hayden for assisting with aerial surveys and G. C. Daigle, Louisiana Department of Wildlife and Fisheries, for piloting the survey aircraft. This project was funded by the Louisiana Department of Wildlife and Fisheries to Louisiana State University and is Contribution 87-22-1390 of the Louisiana Agricultural Experiment Station.