Field-Feeding Ecology of Waterfowl Wintering on the Southern High Plains of Texas

Abstract

ecology of field-feeding dabbling ducks wintering on the Southern High Plains was investigated on a 50-km2 study area in Castro County, Texas, from September to March 1980-82. Most ducks participated in two feeding flights/day to harvested cornfields, which occupied about 45% of the study area. average morning flight was initiated 52 ? 1.5 minutes before sunrise and terminated 23 ? 1.4 minutes later. Evening flights began 25 ? 2.0 minutes after sunset and ended 37 ? 4.2 minutes later. duration of evening flights increased as the season progressed, and birds fed longer and participated more in the evening flight compared to the morning flight of the same day. Colder temperatures and snowfall were associated with longer evening, but not morning, flights. Feeding flocks selected fields based on an abundance-availability hierarchy, apparently attempting to minimize foraging time. Burned fields were preferred when available, followed by disked fields, especially those containing >60 kg waste corn/ha. J. WILDL. MANAGE. 48(1):63-71 Field-feeding by waterfowl is a widely documented occurrence (Bellrose 1976). However, most studies have focused on crop depredation by aggregations of postbreeding waterfowl on the Canadian prairies or in the northern United States prior to fall migration (Bossenmaier and Marshall 1958, Anderson 1959, Winner 1959). Fredrickson and Drobney (1979) emphasized the urgent need for information on the ecology of postbreeding waterfowl, especially from wintering areas where some waterfowl may spend 6-7 months of their annual cycle. Anderson and Batt (1983: 24) summarized a recent workshop on wintering waterfowl and stated, The consensus was that our knowledge of the ecology of wintering habitats is still embryonic .... Field-feeding on waste grain may be of increasing importance to survival of wintering waterfowl as wetland destruction continues and natural food resources decline. However, until the ecology of wintering waterfowl using agricultural habitats is understood, effective management practices will be difficult to implement. This study was initiated to (1) identify the temporal and spatial aspects of field-feeding by dabbling ducks on the Southern High Plains of Texas (SHP); (2) identify factors affecting field selection by fieldfeeding waterfowl; and (3) assess these observations in relation to the quantity and quality of waste grain resources as a means of attracting and supporting populations of wintering waterfowl. This study was conducted on private farmland in Castro County, Texas, and we thank farmers for access privileges to their properties. We especially acknowledge C. L. and C. L. Lee, T. J. and W. J. Hill, J. D. Myrick and family, J. R. Davis and family, D. W. Brown, H. A. McLain, Mr. and Mrs. E. E. Davis, Mr. and Mrs. H. H. Buchanan, F. A. Smith, P. W. Upshaw, W. T. King, H. and R. W. Mitchell, and G. E. Bennett. E. E. Quinlan, G. E. Huber, R. H. Lunn, and R. J. Whyte assisted in all phases of the fieldwork. K. J. Reinecke and S. L. Paulus provided helpful comments on the manuscript. This study was supported by the U.S.D.A. For. 'Present address: Department of Zoology and Entomology, Auburn University, Auburn, AL 36830. J. Wildl. Manage. 48(1):1984 63 This content downloaded from 157.55.39.92 on Tue, 21 Jun 2016 05:07:38 UTC All use subject to http://about.jstor.org/terms 64 WATERFOWL FIELD-FEEDING * Baldassarre and Bolen Serv., Rocky Mountain For. and Range Exp. Stn. through the Great Plains Wildl. Res. Lab., the Caesar Kleberg Found. for Wildl. Conserv., and the Dep. of Range and Wildl. Manage. at Texas Tech Univ. This paper is contribution T-9-292, Coll. of Agric. Sci., Texas Tech Univ.