The Black-capped Vireo (Vireo atricapillus) is a small songbird native to the United States and Mexico. It has been listed as an endangered species in the United States since 1987 and the IUCN classifies this species as vulnerable.
The Black-capped Vireo averages 4.5 inches (12 cm) in length. Males have olive green plumage above and white below with faint yellow flanks. The crown and upper half of the head is black with a partial white eye-ring and lores. The iris is brownish-red and the bill is black. Females are duller in color than males and have a slate gray crown and underparts washed with greenish yellow. First year juvenile males are intermediate in coloration between adult males and females.
The male and female both participate in nest construction as well as incubation of the average 3-4 eggs. The female broods the young, while the male supplies most of the food during the nestling phase. Incubation lasts 14-17 days, and the nestling period 10-12 days. Breeding pairs are capable of producing more than one clutch per breeding season. The male cares for some or all of the fledglings, while the female re-nests – sometimes with another male. The diet mainly consists of beetles and caterpillars.
This species prefers habitat that consists of scattered trees and brushy areas with low foliage for nesting. Territories are sometimes located on steep slopes, where trees are often clumped and intermediate in height. On level terrain, preferred Black-capped Vireo habitat is a mixture of shrubs and smaller trees that average from eight to 10 feet high (2.5-3.5 m). As trees near full size in their territory, the Black-capped Vireo will no longer use that site.
The historic breeding distribution of the Black-capped Vireo extended south from south-central Kansas through central Oklahoma and Texas to central Coahuila, Mexico. At present, the range extends from Oklahoma south through the Edwards Plateau and Big Bend National Park, Texas, to at least the Sierra Madera in central Coahuila, Mexico. In Oklahoma, the Black-capped Vireo is found only in Blaine, Cleveland, and Comanche counties. The winter range of this vireo is not well known but it is thought to winter along the west coast of Mexico from southern Sonora to Guerrero.