Skip to page content
USDA Forest Service

Research & Development Treesearch

Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help - We Participate  Government Made Easy

Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

View PDF (271.0 KB bytes)

Title: Abundance and rates of brood parasitism by brown-headed cowbirds over an elevational gradient in the southern Sierra Nevada

Author: Purcell, Kathryn; Verner, Jared;

Date: 1999

Source: Studies in Avian Biology. 18: 97-103

Publication Series: Miscellaneous Publication

Description: We studied Brown-headed Cowbird (Molothrus ater) parasitism rates in four forest types (ponderosa pine, mixed conifer, true fir, and lodgepole pine) over an elevational gradient in the southern Sierra Nevada. Cowbirds were most abundant and parasitism rates were highest at the lowest sites. All but one of 17 parasitized nests were found in the ponderosa pine type and cowbirds were detected only in ponderosa pine and mixed-conifer forest types. A hypothesis that cowbird breeding and egglaying are limited by late release of livestock at higher elevations was not rejected. Data also supported a second hypothesis-that host abundance and richness influence cowbird abundance and parasitism rates. Bird species richness was a better predictor of cowbird abundance than abundance (total count per plot per year, pooled across species), and models including all passerines were better predictors than models with only host species. Brood parasitism rates were low overall, although rates for Warbling Vireos (Vireo gilvus), Cassin's Vireos (Vireo cassinii), and Black-throated Gray Warblers (Dendroica nigrescens) were high enough to warrant some concern. We recommend continued monitoring of cowbird parasitism rates for these three species in the Sierra Nevada.

Keywords: Black-throated Gray Warbler, brood parasitism, Brown-headed Cowbird, bird species richness, Cassin's Vireo, Dendroica nigrescens, elevation, Molothrus ater, ponderosa pine, Sierra Nevada, Vireo cassinii.

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.



Purcell, Kathryn; Verner, Jared 1999. Abundance and rates of brood parasitism by brown-headed cowbirds over an elevational gradient in the southern Sierra Nevada. Studies in Avian Biology. 18: 97-103


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.