Title: Time and Energy Budgets of American Black Ducks in Winter
Abstract: We used scan sampling techniques to quantify behavior and energy expenditure of American black ducks (Anas rubripes) at Chincoteague National Wildlife Refuge (NWR), Virginia, during the winters of 1985-86 and 1986-87. Time, tide, and habitat influenced black duck behaviors; therefore, diurnal time budgets were constructed by distributing scans over a time-tide matrix within refuge pool, saltmarsh, and tidal-water habitats. Black ducks observed during the day fed least and rested most when in refuge pools, and fed most and rested least when in tidal waters. Estimated daily energy expenditure (DEE) of American black ducks wintering at Chincoteague NWR was similar to values reported in Maine at a given temperature. Although DEE of undisturbed and disturbed flocks were similar, black ducks curtailed feeding and increased time spent in alert and locomotion behaviors in response to disturbance. We suggest that human disturbance of wintering black ducks impairs their physiological condition, thereby reducing winter survival and/or nutrient reserves carried to the breeding grounds. J. WILDL. MANAGE. 53(2):401-410 The decline in populations of American black ducks over the past 3 decades (Steiner 1984) has prompted behavioral research of wintering black ducks. Albright et al. (1983) investigated behavioral responses of wintering black ducks in Maine to temperature, wind chill, and availability of ice-free foraging habitat. Black ducks rested more and fed less with decreasing temperature and increasing ice, even as total DEE increased due to the demands of thermoregulation. Albright et al. (1983) suggested that black ducks in northern wintering areas experience extreme food shortages and that there was evidence of a physiological set-point below which it is more advantageous to rely on energy reserves than to expend energy searching for food. Hickey and Titman (1983) employed scan sampling to study black ducks wintering on Prince Edward Island; ducks fed less and rested more with increased wind chill and tide level. More information is needed to determine the amount of time black ducks spend in various habitats and to measure nocturnal activity (Hickey and Titman 1983). Brodsky and Weatherhead (1985a,b) demonstrated that local food availability can determine black duck behavioral responses to low temperatures in Canada. Brodsky and Weatherhead (1984) also studied the posturing of black ducks while resting and roosting as a mechanism for reducing thermoregulatory costs. They suggested that the management of energy expenditure is as much a consideration as management of energy intake by black ducks. We used the time-budget approach to quantify behavior and energy expenditure of black ducks wintering on, and in the vicinity of, Chincoteague NWR, Virginia. Objectives were to estimate time and energy expenditure within different habitats, identify environmental factors that influence behavioral response, and contrast black duck allocation of time and energy resources in tidal Virginia with results of studies conducted at higher latitudes. We thank M. R. Vaughan and D. R. Stauffer for suggestions and criticisms during the study and D. W. Howerter for field assistance. This study was supported by the U.S. Fish and Wildlife Service and the Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University.
Publication Year: 1989
Publication Date: 1989-04-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 61
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