北美腹地人们最熟悉的一些鸟类，包括冠蓝鸦、知更鸟、蓝知更鸟和鹪鹩，在过去30年因感染西尼罗河病毒而使种群数量急剧下降。该病毒在美国第一次见诸报道的爆发是在纽约市地区，发生在1999年，可能是由一只感染了该病毒的鸟或蚊子进入该地区造成的。对繁育鸟群所做的一项新的研究显示，该事件造成的损失要比人们曾经预料的大得多——大到足以引起人们对该事件对整个生态系统稳定性的影响表示担忧。这项工作反映了一个入侵病原体对本地野生动物能够产生的潜在的毁灭性影响， 也让我们看到了野生动物贸易的潜在危险。
英文原文：
Nature 447, 710-713 (7 June 2007) | doi:10.1038/nature05829; Received 8 November 2006; Accepted 11 April 2007; Published online 16 May 2007
West Nile virus emergence and large-scale declines of North American bird populations
Shannon L. LaDeau1, A. Marm Kilpatrick2 & Peter P. Marra1
Smithsonian Migratory Bird Center, National Zoological Park, Washington DC 20008, USA
Consortium for Conservation Medicine, New York, New York 10001, USA
Correspondence to: Shannon L. LaDeau1 Correspondence and requests for materials should be addressed to S.L.L. (Email: ladeaus@si.edu).
Abstract
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.
