BACHMAN'S SPARROW - Aimophila aestivalis
The Bachman's sparrow is a large sparrow with a flat forehead, a long, dark, rounded tail, and a thin dark line extending back from the eye. Its gray upperparts are heavily streaked with chestnut or dark brown. This sparrow can be found in areas with scattered scrubby vegetation and a dense understory, with or without a tree overstory. Its decline is thought to be from habitat loss. The species is listed ENDANGERED by the Missouri Department of Conservation.
Identification
The Bachman's sparrow is a large sparrow with a large bill, and a fairly flat forehead. It has a long, dark rounded tail. The chest is gray and heavily streaked with chestnut or dark brown. The sides of the head are buffy-gray with a thin dark line extending back from the eye. This sparrow is more reddish in Missouri - the northwestern part of the range - and grayer and darker in the south. Juveniles have a distinct light-colored eye ring and dark streaked throat, breast and sides.
This sparrow is 5.75 inches in length and weighs 6.5 to 8 ounces. They are a secretive species except when protecting their territory.
For a technical description of this bird, refer to:
Robbins, C.S., B. Bruun, and H.S. Zim. 1983. A Guide to Field Identification: Birds of North America. Western Publishing Company. New York, NY. 360 pp.
Life History
Bachman's sparrows arrive in their northern nesting range in March or April. Their nests are built on the ground against or under a grass tuft or low shrub. Nests are found in grassy openings, fields, or areas with scattered trees.
Females lay three to five eggs from April through July. She will have two, sometimes three, clutches of young per year. The female incubates the eggs for 12 to 14 days. Both parents care for the young. Young leave the nest in 10 days, when still unable to fly.
This sparrow eats seeds of herbaceous plants and pines, and insects. They do most of their foraging on the ground.
Bachman's sparrows are a year-round resident in southern states and a summer resident in the states at the northwestern edge of their range, like Missouri. They winter from North Carolina southward, primarily in dense grassy cover.
Habitat and Distribution
Bachman's sparrows live in areas with scattered, scrubby vegetation and a dense herbaceous understory. They are found in dry open pine or oak woods with an undercover of grasses and shrubs; brushy or overgrown hillsides; or overgrown fields with thickets and brambles. In South Carolina, higher densities were recorded in mature (more than 80 years old) pine stands than in young stands.
Historically, Bachman's sparrows were found in mature to old growth southern pine forests that had frequent growing season burns. Bachman's sparrow is a fugitive species, meaning they breed wherever fires remove the forest canopy and create a grass and shrub understory. In contrast to habitat use in most of its range, in Missouri Bachman's sparrows breed on open glades, perhaps a marginal habitat for this species. Missouri is at the northwestern edge of this species' range.
Bachman's sparrows formerly bred from southern Missouri, Illinois, central Indiana,central Ohio, southwestern Pennsylvania, and Maryland, south to eastern Texas, the Gulf Coast, and south-central Florida. It is now absent or local in its northeastern breeding range.
Bachman's sparrow winters in southeastern United States, north to eastern Texas, Gulf states, and southeastern North Carolina.
Cause of Historic Decline
This endangered sparrow has declined over much of its range in the last 50 years. The reasons for its decline are not obvious, but habitat loss is apparently an important factor. Breeding Bird Surveys indicate that 90% of the recorded birds occurred in only three states - Florida, Georgia and Louisiana.
Bachman's sparrows apparently expanded their range early in the 20th century in response to available old field habitats. This type of habitat has since regrown to forest and is no longer available for this bird.Current Threats to Bachman's Sparrow
- Loss of habitat - Cedars have invaded many glades in Missouri making this habitat less suitable for nesting Bachman's sparrows. However, its exact habitat needs are difficult to determine. In Missouri, this sparrow uses marginal or at least different habitat than it uses in the rest of its range.
- Predation - Bachman's sparrows are ground-nesting birds. This leaves the incubating adult and the eggs at risk to predators such as raccoons. In certain portions of its range, house cats allowed to run free kill many adults and nestlings.
- Forest management techniques - Forest management that converts mature natural pine forest to intensively managed pine plantations with no understory vegetation reduces or destroys Bachman's sparrow habitat.
Protection and Management: Steps Toward Recovery
- Habitat protection Glades should be managed to provide open grassy areas. Young Bachman's sparrows require nearby shrubs for shelter during the time they leave the nest but are unable to fly. Core areas of open, mature pine forest should be protected to provide for recolonization of ephemeral habitats created by clearcutting and old field succession.
- Forest management techniques Existing pine savanna should be protected. Moderate to heavy thinning of mid-age pine plantations can make the forest more suitable for nesting Bachman's sparrows. Thinning of forest canopy and controlled burns can create suitable habitat for these birds. Thinning also provides more open habitat for a few years following timber harvest. Old-field habitat was once provided by abandoned farmland. Extensive ground disturbance during site management should be avoided.
- State and Federal Agencies Annual monitoring surveys for singing males and nest sites are conducted by state and federal agencies. Surveys are needed to determine population trends of this species. Glade management on public lands is encouraged by cutting cedars and by prescribed burning of glades that stimulate regeneration of the grassy understory.
Written by Charlene M. Bessken
Missouri and federal law prohibits the importation, transportation, sale, purchase, taking or possession of birds on the State or Federal lists, as well as their eggs and nests.
For more information on the Bachman's sparrow or to report sightings of this species, contact:
Endangered Species Coordinator or Wildlife Ecologist Missouri Department of Conservation Natural History Division P.O. Box 180 Jefferson City, MO 65102 573/751-4115
6/97
