Aiphila aestivalis

INTRODUCTION: Bachman’s Sparrow, formerly known as the Pinewoods Sparrow, was described in the 1830s by John J. Audubon in honor of his colleague, John Bachman, who collected the first specimen in South Carolina in April 1832 (Bent 1968). The scientific name translates to “a summer, thicket-loving bird”. This describes the species fairly well since it is most often heard in the “summer” months and is not often seen because it is “thicket-loving”. This species is best located by its rich, melodic song which is usually a two part song made up of a clear whistle followed by a long trill on a different pitch, which is sung from early February through September. It is the only species of the genus Aimophila that occurs throughout the pineywoods ecoregion of the southeastern United States (Wolf 1977).

DISTRIBUTION: In Texas, the Bachman’s Sparrow occurs only in the far eastern portion of the state (Oberholser 1974, T. O. S. 1995). The TBBAP data indicate that the breeding range of this species is within an area bound by

I-30 to the north, the Trinity River to the west, I-10 to the south and the Louisiana border to the east. Within this area, this sparrow inhabits areas described as either open, mature pine (Pinus sp.) forests with a grassy understory, regenerating pine clearcuts (1-7 years post replanting), or open grassy habitat (Brooks 1987, LeGrand and Schneider 1992, Dunning 1993). In Texas, Bachman’s Sparrow is most abundant in forests on the south side of the Angelina National Forest (personal observation). These areas are managed for open longleaf pine (P. palustris) savannah that the Red-cockaded Woodpecker (Picoides borealis) frequents. Here, frequent prescribed burning maintains the preferred and historical grassy understory among the mature longleaf pines.

SEASONAL OCCURRENCE: The Bachman’s Sparrow is a permanent resident that sings very early in the year. From October through January, it is usually silent and secretive, but it can usually be flushed by walking through its preferred habitat. Only 13.5% of the 37 TBBAP records represent confirmed breeding records; the remainder include 45.9% probable breeding records and 40.5% possible breeding records. All five confirmed records were from the Angelina National Forest (latilong 31094).

Territory sizes in Florida (n = 6) averaged 5.1 ha (12.5 acres), while singing males with unknown territories were found at one male per 33 ha (1.2/100 acres) (McKitrick 1979). In the Missouri glades, Hardin et al. (1982) mapped 13 territories that averaged 0.62 ha (range 0.3-1.3 ha). In 1993 in Texas, Shackelford (unpubl. data) censused Bachman’s Sparrows in the Angelina National Forest and found an average of one singing male per 36.8 ha (1.1/100 acres) from February through August, but the peak was on 24 March with one singing male per 21.5 ha (1.9/100 acres).

Oberholser (1974) states that nesting occurs from mid-April to late July. TBBAP data confirmed one nest with eggs in 1990 on 9 May, while three were located in 1991 on 13 and 26 April and 4 May. The fifth confirmed breeding record was a family group with fledged young that was bachsp.jpg (32812 bytes) photographed 12 September 1991. These latter dates appear to be quite late for the species, but a very wet and rainy spring and summer may have contributed to these late nesting bouts or a second nesting attempt.

BREEDING HABITAT: The Bachman’s Sparrow prefers areas with a high density of herbaceous cover and a low density of mid and overstory (Hardin et al. 1982). The pineywoods portion of the southeastern U. S. with its historically vast, mature, open pine forests and savannahs maintained by frequent fires, was where this species once thrived (Jackson 1988). Today with the dramatic decline of this forest type, this sparrow seems to tolerate treeless, grassy areas, abandoned fields, or early stages of regenerating clearcuts (Hardin and Probasco 1983, Wan A. Kadir 1987, Dunning and Watts 1991, Dunning 1993).

The nest of the Bachman’s Sparrow is usually a dome-type ground nest made of woven grasses (Wolf 1977, Meanley 1989, Dunning 1993). Finding the nest of this skulking species can be difficult since it is usually located at the base of a clump grass like bluestem (Schizachrium sp.) or broomsedge (Andropogon sp.) where it blends in perfectly with the surrounding ground cover.

STATUS: The Bachman’s Sparrow is declining throughout its range (Tate 1986, Sauer et al. 1996) especially in Texas where populations are fragmented and disjunct. This species occurs in open forests that are constantly logged due to the high value of wood products. The suppression of fire has diminished the amount of native grasses as important understory to this species. The conversion of preferred grassy habitats to agricultural fields comprised of non-native grasses maintained by grazing or mowing is probably detrimental to the existence of this sparrow.

Pine plantations (regenerating clearcuts) seem to accommodate the Bachman’s Sparrow for a short period until the young trees grow too dense (Liu et al. 1995). These areas would need to remain in the early seral stage of regeneration if deemed important to this sparrow, which is impractical from a management standpoint. This ephemeral, open habitat resembles the grass-forb layer of the pine savannah habitat in the fire disclimax, longleaf pine ecosystem which once dominated the southern uplands and is the preferred nesting habitat of the Bachman’s Sparrow in the South.  Text by Clifford E. Shackelford (ca. 1997)

Literature Cited

Bent, A. C. 1968. Life histories of North American Cardinals, Grosbeaks, Buntings, Towhees, Finches, Sparrows and allies. Part Two. Dover Publ., Inc., New York, N. Y.

Brooks, R. A. 1987. Avifaunal Populations of Regenerating Clearcut Areas in Eastern Texas, with Emphasis on the Bachman’s Sparrow and Prairie Warbler. Unpubl. M. Sc. Thesis. Stephen F. Austin State Univ., Nacogdoches, TX.

Dunning, J. B. 1993. Bachman’s Sparrow (Aimophila aestivalis). In The birds of North America, No. 38 (A. Poole, P. Stettenheim, and F. Gill, eds.).The Birds of North America,Inc., Philadelphia, PA.

Dunning, J. B., Jr. and B. D. Watts. 1991. Habitat Occupancy by Bachman’s Sparrow in the Francis Marion National Forest before and after Hurricane Hugo. Auk 108(3):723-725.

Hardin, K. I. and G. E. Probasco. 1983. The Habitat Characteristics and Life Requirements of Bachman’s Sparrow. Birding 15(4/5):189-197.

Hardin, K. I., T. S. Baskett, and K. E. Evans. 1982. Habitat of Bachman’s Sparrows breeding on Missouri glades. Wilson Bull. 94(2):208-212.

Jackson, J. A. 1988. The Southeastern Pine Forest Ecosystem and its Birds: Past, Present, and Future. Bird Conservation 3:119-159.

LeGrand, H. E., Jr. and K. J. Schneider. 1992. Bachman’s Sparrow (Aimophila aestivalis). Pp. 299-313 in Migratory Nongame Birds of Management Concern in the Northeast (K. J. Schneider and D. M. Pence, eds.). U.S. Dep. Inter., Fish and Wildl. Serv., Newton Corner, Massachusetts.

Liu, J., J. B. Dunning, Jr., and H. R. Pulliam. 1995. Potential Effects of a Forest Management Plan on Bachman’s Sparrow (Aimophila aestivalis): Linking a Spatially Explicit Model with GIS. Conserv. Biol. 9(1):62-75

McKitrick, M. C. 1979. Territory Size and Density of Bachman’s Sparrows in South Central Florida. Fl. Field Nat. 7(2):33-34

Meanley, B. 1989. Unique shape of a Bachman’s Sparrow nest. Chat 53:12-13.

 

Oberholser, H. C. 1974. The bird life of Texas. Univ. Texas Press, Austin.

 

Sauer, J. R., S. Schwartz, B. G. Peterjohn, and J. E. Hines. 1996. The North American Breeding Bird Survey Home Page. Version 94.3. Patuxent Wildlife Research Center, Laurel, MD.

 

Tate, J. 1986. The blue list for 1986. Am. Birds 40:227-236.

 

Texas Ornithological Society. 1995. Checklist of the birds of Texas, 3rd edition.

 

Wan Ramle, W. A. K. 1987. Vegetational Characteristics of Early Successional Sites Utilized for Breeding by the Bachman’s Sparrow (Aimophila aestivalis) in Eastern Texas. Unpubl. M. Sc. Thesis. Stephen F. Austin State Univ., Nacogdoches, TX.

 

Wolf, L. L. 1977. Species relationships in the avian genus Aimophila. Ornithol. Monogr. 23.