Stress Response in Wintering Green-Winged Teal

Abstract

Stress levels of green-winged teal (Anas creccg carolinensis) wintering on the High Plains region of Texas were determined by measuring a and determining blood glucose, urea nitrogen and uric acid concentrations. The onset of severe weather, particularly when accompanied by high wind velocities, precipitated increased stress levels as shown by our parameters. proved the most useful and reliable parameter for measuring stress. A differential sex ratio, 76:24, was observed apparently because females moved out of the census area in response to adverse weather and the associated stress. Management implications include maintenance of wind breaks as a means of reducing weatherinduced stress on the wintering grounds. J. WILDL. MANAGE. 42(1):87-86 For several months each year thousands of ducks assemble on their wintering grounds, yet biological considerations within these seasonally concentrated populations remain largely unexplored. Indeed, the extent and causes of nonhunting mortality in wintering waterfowl populations are among the least known statistics in waterfowl management (Stout 1967). Friend (1976) estimated that nonhunting winter losses may be twice those inflicted by sport hunting. Stress-induced losses are an unstudied factor in nonhunting mortality for wintering waterfowl populations. We, therefore, measured the effects of weatherinduced stress on green-winged teal by determining a Condition Index and by measuring selected blood parameters. In this study, stress is considered the syndrome induced by nonspecifically-induced changes within the organism as it tries to maintain homeostasis against the pressures of environmental stressors (Selye 1956:5364). Our gratitude is extended to the Rob and Bessie Welder Wildlife Foundation and, especially, to the late Clarence Cottam for financial support of this study. Additional financial assistance was provided by the Institute of University Research, Texas Tech University, through a grant administered by J. Knox Jones, Jr. Bert Blair provided access t Muleshoe National Wildlife Refuge, and J. A. Crawford and J. R. Alford assisted with the field work. John Jones conducted the blood analyses in the laboratory at Methodist Hospital, Lubbock. An early draft of this paper was thoughtfully reviewed by R. B. Owen, Jr.