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 (107 KB)

Title: Prevalence of hematozoa infections among breeding and wintering Rusty Blackbirds

Author: Barnard, William H.; Mettke-Hofmann, Claudia; Matsuoka, Steven M.;

Date: 2010

Source: The Condor 112(4):849–853

Publication Series: Scientific Journal (JRNL)

Description: The Rusty Blackbird (Euphagus carolinus) has declined precipitously over the past several decades,and stressors on both the breeding and wintering grounds are suspected causes. Over 3 years, we collected blood samples from breeding birds in Alaska and Maine and from wintering birds in Mississippi and Arkansas to determine the prevalence of hematozoan infections at different times of the year. The prevalence of hematozoa (percent of birds infected) in Alaska was 44% of 43 birds, lower than previously reported from Newfoundland and Ontario (83% of 23 birds). Blood parasites were found among 67% of 12 Rusty Blackbirds sampled in Maine, not different from the prevalence in Newfoundland and Ontario. Leucocytozoon was the most common parasite; few breeding birds were infected with Plasmodium or Trypanosoma sp. During the winter in Mississippi and Arkansas, the overall prevalence of hematozoa was 49% over three years. In winter as in summer, Leucocytozoon was the most commonly encountered parasite (n = 62 birds), followed by Haemoproteus (n = 5), microfilaria (n = 2), Trypanosoma (n = 2), and Plasmodium (n = 1). The prevalence of hematozoa among wintering Rusty Blackbirds was much higher than expected because winter is generally a time when there are few transmissions and in most birds blood parasites are absent from the peripheral circulation. This high prevalence might indicate a nonseasonal relapse of hematozoan infections among wintering birds; possibly due to high levels of stress, which are known to lower the immune response and trigger nonseasonal relapses.

Keywords: Rusty Blackbird, hematozoa, blood parasites, Leucocytozoon, Haemoproteus, Trypanosoma, microfilaria

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.



Barnard, William H.; Mettke-Hofmann, Claudia; Matsuoka, Steven M. 2010. Prevalence of hematozoa infections among breeding and wintering Rusty Blackbirds. The Condor 112(4):849–853.


 [ 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.