Brown-headed Cowbirds in Grasslands:
Their Habitats, Hosts, and Response to Management
Jill A. Shaffer, Christopher M. Goldade, Meghan F. Dinkins,
Douglas H. Johnson, Lawrence D. Igl, and Betty R. Euliss
Abstract: The brown-headed cowbird (Molothrus ater) is an obligate brood parasite whose numbers have increased in recent decades to the potential detriment of the species that they parasitize. Thus, most management efforts focus on discouraging brown-headed cowbird parasitism or controlling brown-headed cowbird populations. Keys to discouraging cowbird parasitism or controlling populations of brown-headed cowbirds in the Great Plains are maintaining large expanses of grassland, eliminating foraging areas (e.g., feedlots) and perch sites, and reducing the extent of overgrazed pastures.
Key words: brood parasitism, brown-headed cowbird, grassland, management, Molothrus ater
Shaffer, Jill A., Christopher M. Goldade, Meghan F. Dinkins, Douglas H. Johnson, Lawrence D. Igl, and Betty R. Euliss. 2003. Brown-headed Cowbirds in grasslands: their habitats, hosts, and response to management. Prairie Naturalist 35(3):145-186.
This resource should be cited as:Shaffer, Jill A., Christopher M. Goldade, Meghan F. Dinkins, Douglas H. Johnson, Lawrence D. Igl, and Betty R. Euliss. 2003. Brown-headed Cowbirds in grasslands: their habitats, hosts, and response to management. Prairie Naturalist 35(3):145-186. Jamestown, ND: Northern Prairie Wildlife Research Center Online. http://www.npwrc.usgs.gov/resource/literatr/grasbird/bhco/bhco.htm (Version 28MAY2004).
Table of Contents
- Introduction
- Breeding Range
- Suitable Habitat
- Breeding Biology
- Factors Influencing Nest Parasitism
- Home Range Size and Area Sensitivity
- Evidence of Management Effects on Cowbirds
- Methods for Reducing Cowbird Parasitism
- Literature Cited
- Table 1 -- Rates of brood parasitism in nests of grassland bird species that are known victims of brown-headed cowbirds.
Acknowledgments
Funding was provided by the Prairie Pothole Joint Venture, U.S. Fish and Wildlife Service, U.S. Geological Survey, U.S. Forest Service, and The Nature Conservancy. Stephen K. Davis, Elmer J. Finck, William E. Jensen, D. Glen McMaster, Pamela J. Pietz, Terry L. Shaffer, and an anonymous referee provided comments on the manuscript. We thank Stephen K. Davis, Ken D. De Smet, Scott D. Hull, D. Glen McMaster, Glenn C. Sutter, and Maiken Winter for sharing information on parasitism rates and results from their studies.
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