, Volume 1, Issue 1, pp 60–68 | Cite as

Impact of West Nile Virus on American Crows in the Northeastern United States, and Its Relevance to Existing Monitoring Programs

  • Wesley M. Hochachka
  • André A. Dhondt
  • Kevin J. McGowan
  • Laura D. Kramer
Original Contribution


We assessed the changes in abundance of American crows in the northeastern U.S. following the arrival of West Nile virus (WNV), with two aims. First, we determined the impact and spatial extent of the initial epizootic that began in New York City. Second, we examined whether two existing surveillance programs monitoring for WNV (data from 2000 New York State dead bird testing, and 2000 mosquito testing) accurately predicted the observed impact of the disease on crow populations as measured using data from the North American Christmas Bird Count. The rationale for this second aim was that the two WNV surveys were new and with unknown biases and sensitivity, while the Christmas Bird Count has existed for decades, providing monitoring before the arrival of WNV in North America and a long time series of data useful in gauging sensitivity. As a result, the Christmas Bird Count represents a good benchmark against which to compare the two new surveillance programs. Consistency among these three sources of information was low, suggesting that while dead bird and mosquito surveys can currently indicate the later stages of severe outbreaks, the ability to consistently detect early stages of outbreaks is questionable.


American crow Corvus brachyrhnchos monitoring population decline surveillance West Nile virus 



The data needed to conduct this study could not have been gathered without the dedicated volunteers who annually conduct the Christmas Bird Count, which is coordinated by the National Audubon Society. IT staff at the Cornell Laboratory of Ornithology maintained the database. Monitoring of dead birds also required the participation of the general public. All West Nile virus surveillance data were gathered by the New York State West Nile Virus Surveillance Team.


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Copyright information

© EcoHealth Journal Consortium 2004

Authors and Affiliations

  • Wesley M. Hochachka
    • 1
  • André A. Dhondt
    • 1
  • Kevin J. McGowan
    • 1
  • Laura D. Kramer
    • 2
  1. 1.Laboratory of OrnithologyCornell UniversityIthaca
  2. 2.Wadsworth CenterNew York State Department of HealthAlbany

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