Bachman's sparrow (Peucaea aestivalis), also known as the pinewoods sparrow or oakwoods sparrow, is a small American sparrow that is endemic to the southeastern United States. This species was named in honor of Reverend John Bachman.
Adults have rufous brown upperparts and crown with gray and black streaking on the nape, back and primaries. The face is gray with a rufous brown eyestripe. It has a buff colored breast and whitish belly. These are mid-sized New World sparrows, measuring and weighing .CRC Handbook of Avian Body Masses, John B. Dunning Jr. (ed.). CRC Press (1992), .
Their breeding habitat is open pine forests. The domed nest is usually built on the ground near a clump of grass or a bush. Females lay three to five eggs.
Bachman's sparrow is primarily a non-migratory resident, but it may retreat from some of the most northerly territories. The species is mainly a granivore, but it will also take some insects.
This bird is considered near threatened by the IUCN, with habitat loss one of the major factors often cited in its decline. Habitat degradation due to later stages of forest succession has also been attributed to the decline of this species. Prescribed forest burns may assist in recovery.
The primary song begins as a clear whistle, followed by a short trill.Nguyen, L., K. Donas, J. Jackson, R. Kannan. 2024. Geographical variation in songs of Bachman's Sparrow (Peucaea aestivalis). Journal of the Arkansas Academy of Science: 78:52-58. https://doi.org/10.54119/jaas.2024.7808 Available at: https://scholarworks.uark.edu/cgi/viewcontent.cgi?article=3551&context=jaas
Distribution Bachman's sparrows occur primarily in the southeastern United States from the central region of peninsular Florida north to southeastern North Carolina and west through portions of Tennessee, Kentucky and Missouri to eastern Oklahoma and eastern Texas. Following forest conversion and the spread of agricultural fields up into the early 1900s, Bachman's sparrows rapidly expanded their range and began breeding in Illinois, Indiana, Ohio, West Virginia, Virginia, Maryland, and parts of Pennsylvania.Mumford, Russell E.; Keller, Charles E. 1984. The birds of Indiana. Bloomington, IN: Indiana University Press .Stevenson, Henry M.; Anderson, Bruce H. (1994). The birdlife of Florida. Gainesville, FL: University of Florida Press However, this trend reversed during the 1930s as much of the eastern deciduous forest recovered. Bachman's sparrows are thought to have been extirpated from Virginia in the early 2000s, and North Carolina is now the northern periphery of their eastern range.
Among the three subspecies of Bachman's sparrow, Peucaea aestivalis aestivalis breeds furthest east, from southeast South Carolina to peninsular Florida. Peucaea a. bachmanii occurs west of P. a. aestivalis to Mississippi and north to Kentucky. P. a. illinoensis occurs in the westernmost region of the species' range.
Timing of major life events
Migration Reviews and a field guide summarize the limited information available on Bachman's sparrow migration.National Geographic Society. 1999. Field guide to the birds of North America. 3d ed. Washington, DC: The National Geographic Society Bachman's sparrows in the southern portion of their range are resident, while those in Missouri, Arkansas, eastern Oklahoma, Tennessee, Virginia, parts of North Carolina, and extreme northern Mississippi and Alabama have been thought to migrate south during winter. Historical records suggest that Bachman's sparrows that once bred from Illinois to Pennsylvania did migrate to the south. Records of Bachman's sparrow occurrence on breeding grounds and specimens of subspecies collected outside their normal breeding range suggest that spring migration occurs from mid-March to May and fall migration occurs from late August through to late October. However, migration of Bachman's sparrows in the northern part of their current range is not well understood and it may be that suitable habitat conditions do not necessitate migration. Because of their secretive nature, determining the presence of Bachman's sparrows is difficult outside of the breeding season, when individuals rarely sing and perch visibly. However, examination of eBird data from recent decades suggests that several populations of Bachman's sparrows remain in North Carolina for the winter.
Breeding Bachman's sparrows' breeding season typically begins in April and continues through August. The earliest date for Bachman's sparrow eggs in Florida is 14 April and the latest date is 4 August. The earliest Bachman's sparrow nest found during a study in longleaf pine habitat of South Carolina was 10 April, while the latest nest found was early in the incubation stage on 5 August. In a study of Bachman's sparrow reproduction in shortleaf and loblolly pine plantations of Arkansas, egg laying started as early as 17 April and continued until 26 August. However, 85% of clutches were started in May, June, or July.
Bachman's sparrows typically raise two broods per breeding season and will renest after failed attempts. In shortleaf and loblolly pine plantations of Arkansas, the average time between fledging of the first brood and starting the second brood was 12.3 days. This was not significantly (p=0.39) different from the 9.7-day average period between a failed nest and a subsequent nest attempt. On average, females attempted 3.1 nests per season. The maximum number of attempts per season was five. The maximum number of nests attempted in longleaf pine habitat of South Carolina was also five. After two successful nests, a female attempted three times to raise a third brood. Limited evidence suggests that three broods per season may occur occasionally.
Bachman's sparrow nests are constructed on the ground by females and are primarily made of grasses. All nests (n=71) found in a study in shortleaf and loblolly pine plantations of Arkansas were built on the ground. Most nests (70%) were built at the base of bluestem clumps (Andropogon spp.), although nests were found at the base of small trees, forbs, and other grass species. Bachman's sparrow nests are dome-shaped with an opening typically oriented to the north. However, there is some variation in nest shape and on the Arkansas study site above, only 7% of nests were not either partially or completely domed. Bachman's sparrow nest shape may vary geographically, as nests found farther north in their historic range were infrequently domed.
Clutch size varies from three to five. Average clutch size on a site in Arkansas was 3.9, while in a longleaf pine community in South Carolina mean clutch size was 3.6. Both of these studies found significant (p≤0.02) decreases in clutch size as the breeding season progressed. On a dry prairie site in Florida (n=9) average clutch size was 3.44 and on another (n=5) it was 3.6. In shortleaf and loblolly pine plantations of Arkansas, females laid an average of 11.6 eggs (n=20) over the course of the breeding season.
In shortleaf and loblolly pine plantations in Arkansas, females incubated eggs for 13 to 14 days. The average nestling period was 9 days, and the average period between fledging and independence was 25 days. Both parents care for the young during these periods. A review suggests that Bachman's sparrows probably breed the year after hatching.
Bachman's sparrows exhibit some fidelity to breeding sites. Over a two-year period in shortleaf and loblolly pine plantations of central Arkansas, 6 of 34 adults returned to areas where they had a territory in a previous year. This varied across years, with a 29% return rate of adult birds banded in 1983 and none of the adults banded in 1984 returning to the site in 1985. No juveniles (n=60) returned to the site.
Nesting success Values of nest success reported for Bachman's sparrows vary. Daily nest survival rate of Bachman's sparrow ranged from 0.89 to 0.96 across sites and years in the dry prairie of central Florida. On average 3.13 birds were fledged per successful Bachman's sparrow nest. Estimates of productivity ranged from 1.21 to 4.16 offspring per pair per year across sites and years. In a South Carolina longleaf pine community, daily survival rate of Bachman's sparrow nests in 1995 was 0.952, which was significantly (p=0.04) higher than the 1996 daily nest survival rate of 0.889. Earlier nesting attempts (before June 15, n=15) had significantly (p=0.05) higher survival rates than those started later in the year (n=11). Daily nest survival rate was 0.922 during incubation and 0.973 during the nestling stage. In central Arkansas, daily success rate during the incubation period was 0.965, while in the nestling period it was 0.919. In the glades of south-central Missouri, 8 female Bachman's sparrows fledged an average of 1.5 young per season over 2 years. Predation accounted for 80% of egg loss on study sites in Arkansas and 94% of nest failures on sites in central Florida. Daily survival rates of nests in the Sandhills of North Carolina were 0.947 and 0.951. Nest survival in North Carolina and South Carolina declined significantly later in the breeding season.
Information on Bachman's sparrow nest predators can be found in the Predators section of this summary. Cowbirds, nest abandonment, and prescribed fire are other known causes of nest failure. There are several accounts of Bachman's sparrow exhibiting nest defense behavior. One study recorded video evidence of a Bachman's sparrow successfully leading a cottonmouth away from its nest. In the same study, three individuals used ptiloerection and two individuals chased away an approaching cotton rat. There have also been some reports of Bachman's sparrows which feign injury or imitate the movement of a snake, even emitting a hissing noise, at the approach of danger.
Survival Survival of Bachman's sparrows during the breeding season has been investigated in a South Carolina study area dominated by longleaf pine. Recapture of banded birds resulted in a monthly survival rate during the breeding season of 0.94. Using radio telemetry, average survival of Bachman's sparrows from 20 April to 26 July was 80.0%. In another radio telemetry study, four mortalities out of 38 Bachman's sparrows were documented over two years. The overall breeding season survival rate was estimated as 0.893. According to a literature review, Bachman's sparrows have been captured that were at least three years old.
Preferred habitat Bachman's sparrows inhabit areas with a dense layer of ground vegetation and open mid-stories with scattered shrubs and saplings, including young clearcuts and open pine (Pinus spp.) forests.Chambers, Rachel J. 1994. Habitat relations of Bachman's sparrows and other birds on Missouri glades. Columbia, MO: University of Missouri-Columbia. Thesis
Habitat characteristics