Letter | Published:

West Nile virus emergence and large-scale declines of North American bird populations

Nature volume 447, pages 710713 (07 June 2007) | Download Citation



Emerging infectious diseases present a formidable challenge to the conservation of native species in the twenty-first century1. Diseases caused by introduced pathogens have had large impacts on species abundances2, including the American chestnut3, Hawaiian bird species4 and many amphibians5. Changes in host population sizes can lead to marked shifts in community composition and ecosystem functioning3,4,6. However, identifying the impacts of an introduced disease and distinguishing it from other forces that influence population dynamics (for example, climate7) is challenging and requires abundance data that extend before and after the introduction2,5. Here we use 26 yr of Breeding Bird Survey (BBS)8 data to determine the impact of West Nile virus (WNV) on 20 potential avian hosts across North America. We demonstrate significant changes in population trajectories for seven species from four families that concur with a priori predictions and the spatio-temporal intensity of pathogen transmission. The American crow population declined by up to 45% since WNV arrival, and only two of the seven species with documented impact recovered to pre-WNV levels by 2005. Our findings demonstrate the potential impacts of an invasive species on a diverse faunal assemblage across broad geographical scales, and underscore the complexity of subsequent community response.

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This study is based on work supported by the Smithsonian Institution, The National Science Foundation under a grant awarded to S.L.L., a NIAID contract, and the joint NSF-NIH Ecology of Infectious Disease program (A.M.K., P.P.M). We thank C. Robbins and the United State Geological Survey for creating and maintaining the BBS monitoring programme. We also thank all BBS data support and volunteers, as well as C. Calder, J. S. Clark, W. A. Link, J. R. Sauer, C. Studds and W. Thogmartin for comments.

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  1. Smithsonian Migratory Bird Center, National Zoological Park, Washington DC 20008, USA

    • Shannon L. LaDeau
    •  & Peter P. Marra
  2. Consortium for Conservation Medicine, New York, New York 10001, USA

    • A. Marm Kilpatrick


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Competing interests

Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.

Corresponding author

Correspondence to Shannon L. LaDeau.

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    Supplementary Information

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