After an outbreak of West Nile virus (WNV) infections in people, horses, and wildlife in Staten Island, NY, during the summer of 2000, we surveyed the bird population of the island for evidence of infection. Neutralizing antibodies were detected in 59 of 257 (23.0%) resident birds and none of 96 transient (migrating) birds sampled in early October. Species with the greatest seroprevalence were northern cardinal (Cardinalis cardinalis) (69.2%) and rock dove (Columba livia) (54.5%). House sparrows (Passer domesticus) and chickens (Gallus gallus) had lower than expected seroprevalences, 8.6% and 5.5%, respectively. The geographic distribution of seropositivity suggested focal transmission at several locations on the island. The concentration of seropositive birds among resident bird populations on Staten Island supports the concept that many birds survive WNV infection and that some of these play an important role in the WNV-bird-mosquito transmission cycle.