Time-Activity Budgets of Mottled Ducks in Louisiana in Winter

Abstract

I related time-activity budgets of mottled ducks (Anas fulvigula) in coastal southwestern Louisiana from September-February 1981-82 to sex, pair status, and environmental factors. Mottled ducks spent 43% of their time feeding, 36% resting, 9% preening, 7% alert, 6% locomoting, and <1% each in courtship and agonistic activities. Paired and unpaired ducks spent similar amounts of time feeding (P = 0.937). Feeding rates were lowest during October-December. Mottled ducks fed more at night than during the day (P < 0.01). Pairs spent more time resting than unpaired ducks (P < 0.001). Time spent resting was similar among months during winter and between night and day (P = 0.359). Unpaired ducks spent more time locomoting (P < 0.01) and alert (P < 0.01) than pairs. Preening, alert, and locomotor activities were observed less often at night than day and occurred at similar rates each month throughout winter. Courtship and agonistic activities were most common during September-December. By December, 90% of females were paired. Activity patterns of mottled ducks, which breed in a semitropical region, were similar to ducks wintering in Louisiana and breeding in more temperate regions. Because nearly all (95%) foraging by mottled ducks occurred in water depths <15 cm, management should provide shallow-water wetlands with abundant plant and animal foods. Deeper, open-water areas should be provided for loafing habitat and escape from predators. J. WILDL. MANAGE. 52(4):711-718 The mottled duck is 1 of 5 mallard-like ducks found in North America (Johnsgard 1961). Mottled ducks inhabit the Gulf coast region from Laguna de Tamiahua south of Tampico, Mexico, north to the Pearl River in Mississippi and are found in greatest numbers in Louisiana and Texas (Stutzenbaker 1984). Krapu (1981) suggested that condition of mallards (A. platyrhynchos) during winter may influence subsequent breeding success. Because mottled ducks are nonmigratory, habitat management programs designed to benefit these birds in winter may directly affect the number of birds breeding in and using the management area in the future. Recent surveys indicated that mottled duck numbers declined by about 50% during the past decade (Stutzenbaker 1984). Intensive management of winter habitat may be crucial for restoring numbers of mottled ducks to former levels. Social behaviors and habitat use of mottled ducks have been studied during the breeding (Allen 1980, Baker 1983, Paulus 1984) and nonbreeding (Weeks 1969, White and James 1978) periods. However, little is known of the importance of other activities during winter. I examined time-activity budgets of mottled ducks during winter and the influence of sex, social status, time of day and year, habitat use, and weather on time-activity budgets. These data were used to suggest management practices of benefit to mottled ducks. I am especially grateful to K. A. R. Paulus for her support during the study. I thank G. A. Baldassarre, M. K. Causey, T. Joanen, J. E. Kennamer, L. McNease, R. E. Mirarchi, G. R. Mullen, D. M. Richard, and L. C. Wit for their assistance in study design, data collection and valuation, and manuscript preparation. I appreciate the help of A. B. Ensminger, H. A. Bateman, Jr., and J. W. Tarver, for securing financial assistance, providing logistical support, and sharing information on the ecology of mottled ducks. Financial support was provided by the Louisiana Department of Wildlife and Fisheries. STUDY AREA AND METHODS I observed mottled ducks in coastal southwestern Louisiana, primarily on Rockefeller State Wildlife Refuge (SWR). Rockefeller SWR, an area of 30,786 ha, was bounded on the south by the Gulf of Mexico and on the north by the Grand Chenier ridge complex (Wicker et al. 1983). A description of the area was presented in Paulus (1982). In addition, I observed mottled ducks on privately-owned fresh, intermediate, and brackish marshes within 35 km of Rockefeller SWR. Much of this area was impounded by dikes, spoil banks, or natural levees that modified natural water Present address: Innovative Research Services, P.O. Box 371, North Bend, WA 98045.