The Nesting, Reproductive Performance, and Chlorinated Hydrocarbon Residues in the Red-Tailed Hawk and Great Horned Owl in South-Central Montana
Year: 1971
Type: article
Abstract: I N this paper, we describe the nesting, reproductive performance, and chlorinated hydrocarban residues, and evaluate current population status of the Red-tailed Hawk (B t J u eo ' amaicensis) and Great Horned Owl (Bubo virginianus) in south-central Montana.We conducted the field work during June and July, 1966, and March-July, 1967, incidental to but as background information for studies of the response of juvenile Red-tailed Hawks and Golden Eagles (Aquilu chrysaetos) to DDT in their diet (Seidensticker, 1968) and the population status of the Golden Eagle (Reynolds, 1969).THE STUDY AREA The topography of northern Park, western Sweetgrass, and southern Meagher Counties, Montana, where we conducted this study, is characterized by river flood plains, gentle transitional foothills, and timbered mountain slopes.An alpine zone occurs at the highest elevations.Elevations range from 10,OO feet in the Bridger, Gallatin, Crazy, and Absaroka Mountain Ranges, which border the area, to 4,000 feet along the Yellowstone, Boulder, and Shields Rivers.Cottonwood trees (Populus spp.) and willows (S&x spp.) dominate vegetation on the river and creek flood plains at the lower elevations where we concentrated our search for hawk and owl nests.METHODS We located hawk and owl nests using the procedure outlined by Craighead and Craighead (1956:196-199).To obtain tissue for analysis of chlorinated hydrocarbon insecticide residues, we used a biopsy technique (Seidensticker, 1970a) or sacrificed the bird.Each egg that we analyzed came from a different nest.We placed large tissue samples and eggs in separate double polyethylene bags; small samples (collected via biopsy) were placed in clean, screw-top, five ml vials.We stored all samples in a freezer.The WARF Institute, Inc., Madison, Wisconsin, analyzed tissues and eggs with a gas chromatograph following the procedure outlined by the U.S. Food and Drug Administration (USFDA, 1964).Samples from one Great Horned Owl egg and one Red-tailed Hawk egg were reextracted, cleaned up, and hydrolyzed (treated with alcoholic KOH) to check for polychlorinated biphenyls (Risebrough et al., 1969; Anderson et al., 1969).D. W. Anderson of the University of Wisconsin measured and weighed the hawk and owl eggshells using the procedures described by Hickey and Anderson (1968).
Authors: Seidensticker, John C, Reynolds, Harry V
Language: English
Topic: Avian ecology and behavior
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: green
Funder: University of Montana
OpenAlex ID: W415772317