Bachman's Warbler

Vermivora bachmanii

Description

The rarest native songbird of the United States, Bachman's warbler is smaller than a sparrow and has a slender, somewhat downcurved bill. One of the smallest warblers, its total length being 4-4.5 in (10-11.2 cm) The male is olive green above, face and underparts yellow, throat patch and crown patch black. The female lacks the black throat; the upper parts are olive green, the forehead and underparts yellow, and the crown grayish.

Behavior

Although little information is available on food habits, an insect diet is suspected. A 1924 record indicates that five stomachs of this species from Alabama contained the remains of caterpillars and a few fragments of Hymenoptera, probably ants. Migrants were observed in 1891 in Florida feeding in the dead clustered leaves of hackberry and among the terminal leaflets of other tree branches—the feeding action being rather slow and deliberate, and with the birds sometimes hanging with the back downward while feeding.

All of the known nests have been discovered in undergrowth within a few feet of the ground. Nesting has been recorded from late March to early June, with clutch size usually being three or four eggs, but occasionally five. The birds begin migrating southward during July and apparently pass through Key West by early September.

Habitat

Historic records indicate the Bachman's warbler nested in low, wet forested areas containing variable amounts of water, but usually with some water that was permanent. These areas were described in general as being forested with sweet gum, oaks, hickories, black gum, and other hardwoods; and where there was an opening in the forest canopy, the ground being covered with dense thickets of cane, palmetto, blackberry, gallberry, and other shrubs and vines. When not on or near their nests, which were located near the ground, the birds were more often observed high in the tree tops, especially during migration.

Distribution

The Bachman's warbler breeds in the Southeastern United States and winters in western Cuba and the Isle of Pines. Meager records indicate the birds migrated southward in late summer and returned in early spring, with one group apparently moving generally along the East Coast, and another skirting the Gulf Coast and continuing up the Mississippi Valley. The fact that a good portion of the migrants funneled through the Florida Keys is supported by a number of sightings at Key West, and a record of 21 of the birds being killed on March 3, 1889, when they struck the light at Sombrero Key. Exact population numbers are unavailable; but, the population is known to be extremely low. The only confirmed nest observations were recorded during the period from 1897 to 1937. Of these, 26 were from the I'On Swamp area, several Louisiana locations, Kentucky, Maryland, and near the Long/McIntosh County line in Georgia. Most authorities agree that if the Bachman's warbler still exists it is most likely in the I'On Swamp area in Charleston and Berkeley Counties, South Carolina.

Threats

A precipitous decline in abundance apparently began around 1900, and extended into the 1940s or 1950s. The cause is unknown, but it is suspected to have been from the loss of canebreak habitat both in the United States and Cuba.

Conservation and Recovery

An intensive survey is needed to locate breeding pairs so that all possible measures might be taken to protect both the birds and the associated habitat. A survey is now being conducted on the South Carolina coast, the most important historical nesting area for the species. Researchers believe that the habitat near this bird's last known nesting sites may have improved after Hurricane Hugo because the forest canopy was removed from many areas. No confirmed breeding records have been reported from the United States since the mid-1960s. Several sightings have been made on Cuban wintering grounds during the last decade. In 1999, the Fish and Wildlife Service published a multi-species Recovery Plan for South Florida, in which it was recommended that surveys for the Bachman's warbler should continue.

Contact

U.S. Fish and Wildlife Service
Jacksonville Ecological Services Field Office
6620 Southpoint Drive South, Suite 310
Jacksonville, Florida 32216-0958
Telephone: (904) 232-2580
Fax: (904) 232-2404
E-mail: dave_hankla@fws.gov
http://www.fws.gov/r4jafl/

References

Bent, A.C. 1953. "Life histories of North American wood warblers." U.S. National Museum Bulletin 203.

Hooper, Robert G., and Paul B. Hamel. 1976. "Nesting habitat of Bachman's Warbler—A Review." U.S.D.A., Forest Service, Southeastern Forest Experiment Station, Clemson, South Carolina.

Stevenson, H.M. 1938. "Bachman's Warbler in Alabama." Wilson Bulletin 50:36-41.

U.S. Dept. of the Interior. 1973. "Threatened Wildlife of the United States." U.S. Government Printing Office, Washington, D.C. 289 pp.

U.S. Fish and Wildlife Service. 1999. "South Florida Multi-species Recovery Plan." Vero Beach, Florida.