Perception Channels: visual ; tactile ; acoustic ; chemical
In October of 1987 the U.S. Fish and Wildlife Service placed V. atricapilla on the endangered species list. These birds face extinction primarily because of nest parasitism by female brown-headed cowbirds. it is believed that up to 90 % of black-capped vireos' nests are infected by these brood parasites. The actual process shows that in most cases the female parasite will actually remove the hosts' eggs from an untended nest and then deposit her own. Even if the hosts' eggs are not removed, the vireos still have great odds against survival due to the fact that the incubation period of the brown-headed cowbird is shorter (10 - 12 days) than the Black-capped vireos (14 - 17 days). The hosts' eggs still have even greater odds against their survival if they do hatch because they rarely can compete for nest space and food with the older and larger cowbird hatchlings.
In addition, severe habitat loss, due to urbanization and over-browsing by animals, adds to the susceptibility to extinction of V. atricapilla. Before the 1950's, V. atricapilla was found in Kansas and Oklahoma, as well as in Texas. The last reported sighting of V. atricapilla in Kansas was in 1953.
Fortunately, habitat management and conservation is taking place at many Texas state parks and recreation areas in order to preserve the remaining and dwindling population. Also extermination, of some of the plentiful, brown-headed cowbird populations that take part in nest parasitism which in turn affects the reproductive success of the black-capped vireos, is currently taking place.
(Tveten 1987; Perrins & Middleton 1985; Robbins, Brunn & Zim 1983)
US Federal List: endangered
IUCN Red List of Threatened Species: vulnerable
Economically, the decline in the population of the black-capped vireo has had a negative impact on humans in terms of restrictions on urban growth and development needed to meet the expanding demographics of the Central Texas area.
Black-capped vireos are active feeders that like to eat insects. Their diet consists primarily of caterpillars and beetles. Young birds seem to prefer spiders as a supplement to their diet while adults prefer berries. Both glean the insects from foliage in a "characteristic pose" of hanging upside down and then fluttering to a lower branch. (Tveten 1987)
The range of V. atricapilla extends from Northern, Western and Central Texas to Northern Mexico. During the summer V. atricapilla breeds primarily in the Edward's Plateau of Central Texas. In the winter (non-breeding season), V. atricapilla can be found in the flatlands and Pacific foothills of Western Mexico (throughout the states of Sonora and Guerrero). (Scott 1987; Tveten 1987)
Biogeographic Regions: nearctic (Native )
In general, black-capped vireos prefer low thickets in scrub-oak woodlands, arid hilly regions and ledges on steep hills near water. It is believed that the largest known concentration of V. atricapilla can be found near Austin, Texas, located in the Edward's Plateau region which encompasses 17 % of the state of Texas. Geographically, this area consists of oak thickets combined with heavy ground cover as well as shallow, rocky canyons that receive abundant, bright sunlight. These places are described as "the hottest places imaginable", for birds at least. (Kutac 1989; Tveten 1987)
V. atricapilla is the smallest and most distinctly marked of all North American Vireos. This bird is fairly small with an average height of 11 cm and wingspan of 16.5 cm. This bird is unique in that it is the only North American bird to have white spectacles on a jet-black head. The female, however, has more of a slate-gray head coloration. Both males and females have red eyes and yellow to whitish wing bars. These birds are generally olive above and white below with yellow flanks. The female is smaller in size and juveniles are more brown above , rather than olive, and buffy below. Black-capped vireos are also distinctly different from all other New World, neo-tropical Vireos because of their quick action, bold patterns and quick flight. The flight of V. actricapillus is quick, nervous and rarely sustained. (Oberholser 1974; Tveten 1987; Scott1987)
Other Physical Features: endothermic ; bilateral symmetry
V. atricapilla arrives at its breeding region in early March and has migrated south by late September. The actual breeding begins in mid-April and ends in early August. These birds are monogamous. The nests of the birds can be found in forked twigs of small trees or shrubs, usually 2-6 ft. up (rarely any higher). The actual nest is compact, cup-like and rounded in shape with thick walls. It is composed of leaves, coarse grasses, bark strips, catkins and spiders' cocoons, all bound together and supported with long plant fibers, spider webs and wool. The inside of the nest is lined with finer grasses. The nests are built by both males and females but the majority of the work is done by the female. The nest is built within six to nine days. Females have a clutch size of three to five eggs. The eggs of V. atricapilla are sub-elliptical to long sub-elliptical. On the exterior they are smooth but non-glossy, pure white and unmarked. Once again, black-capped vireos show their uniqueness in that their eggs are unmarked while all other vireos have spotted eggs. The average size of the egg is 18 x 13 mm. Incubation time ranges from 14 -17 days. Both males and females take turns in keeping the clutch warm. When the altricial nestlings hatch, they are naked with yellowish to pink skin. Males bring 75 % of the nestlings' food. They are fed for another four to seven days. The young leave the nest about ten to twelve days after hatching. Black-capped vireos have a success ratio of one to two chicks per two adult pairs. This low success ratio is attributed to female brown-headed cowbird nest parasitism. (Ehrlich et al 1988; Baicich & Harrison 1997; Tveten 1987, Oberholser 1974)
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
The black-capped vireo (Vireo atricapilla) is a small bird native to the United States and Mexico. It was listed as an endangered species in the United States in 1987. Successful conservation efforts on the U.S. Army's Fort Hood and Fort Sill contributed to delisting of the black-capped vireo in 2018.[3][4]: 16236 The IUCN lists the species as "near threatened."[1]
The black-capped vireo is a songbird about 12 cm (4.5 inches ) in length. Sexually mature males are olive green 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 males often have more extensive gray in the cap, similar to adult females.
The male and female in a pair assist in nest construction and incubation. Typically, the female lays three or four eggs. The incubation period is 14 to 17 days, and the nestling period is 10 to 12 days. The female broods over the young, while the male supplies most of the food during the nestling phase. 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 nests again, sometimes with another male. These birds are insectivorous, with beetles and caterpillars making up a large part of their diet.
Black-capped vireos nest in "shinneries", brushy areas with scattered trees. Shinneries primarily consist of shin oak or sumac. Appropriate height and density are important factors for this species' breeding success. Foliage that extends to ground level is the most important requirement for nesting. Most nests are between 15 and 50 in (35–125 cm) above ground level, and are screened from view by foliage. Territories are sometimes located on steep slopes, where trees are often clumped and intermediate in height. On level terrain, the preferred black-capped vireo habitat is a mixture of shrubs and smaller trees that average from 8-10 ft high (2.5-3.5 m). Black-capped vireos stop using sites where many trees are nearing full size.
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, Cotton and Comanche Counties. The winter range of this vireo is not well known. It is thought to winter along the west coast of Mexico from southern Sonora to Guerrero.
The black-capped vireo is threatened by brown-headed cowbird (Molothrus ater) brood parasitism, human disturbance, and loss of habitat to urbanization, fire exclusion, grazing, and brush control. With population sizes now well into the tens of thousands, the species continues to be managed by the Texas Parks and Wildlife Department and the Oklahoma Department of Conservation. Conservation efforts by the U.S. Army are continuing to enhance the conservation status of the black-capped vireo.
The black-capped vireo (Vireo atricapilla) is a small bird native to the United States and Mexico. It was listed as an endangered species in the United States in 1987. Successful conservation efforts on the U.S. Army's Fort Hood and Fort Sill contributed to delisting of the black-capped vireo in 2018.: 16236 The IUCN lists the species as "near threatened."
