In an endemic habitat of Venezuelan encephalitis virus at Sontecomapan, Veracruz, Mexico, VE virus was isolated from pooled heart, lung, and kidney tissues of one resident hummingbird (Long-tailed Hermit) collected in August 1963. This isolation was from 1 of 36 of this species and 773 resident birds tested. Antibody to VE virus was found by hemagglutination-inhibition (HI) tests in 2 of 284 resident birds, and by neutralization (N) tests in 1 of 82 residents. Virus was not recovered from organ or blood samples from 1,396 migrant birds of 59 species at Sontecomapan; migrants were not tested for antibodies. At the Minatitlan heronries, 246 nestlings of 10 species yielded no virus from organs or blood, but when 238 birds were tested for HI antibody and 201 for N antibody, HI antibody was found in 1 Common Egret and 2 Black-crowned Night Heron nestling juveniles, and N antibody, possibly maternal in origin, in 4 Common Egrets, 2 Black-crowned Night Herons, and 1 Boatbilled Heron. Thus about 1% of resident birds at Sontecomapan and 1% to 3% of nestling juvenile herons at Minatitlan showed antibody evidence of infection by VE virus.