The fortunes of Field Sparrows in any area vary with the successional stage of their preferred habitats, abandoned fields, clearcuts or burned land, regrowing with scattered shrubs and small trees. Unfortunately for the sparrows this is not a climax stage. The trees and shrubs grow into a woodland, shading out the grasses and forbs whose seeds provide food for these sparrows.
Two subspecies are recognized for this species with the 100th meridian as the approximate dividing line, although Oberholser (1974) reports only the western subspecies (S. p. arenacea) breeds in Texas. The Nebraska (S. p. perissura) and Texas (S. p. vernonia) subspecies of Oberholser (1974) are now considered part of the western subspecies (Pyle 1997). The statement in Carey et al, (1994) that Field Sparrow has no recognized subspecies is a misunderstanding.
DISTRIBUTION. During the 1987-1992 field work seasons of the TBBA project, observers found Field Sparrows in many parts of the eastern two-thirds of the state, with the densest concentration of breeding sites in the northeast corner of the state and on the east edge of the Edwards Plateau. Many sites were scattered throughout the Rolling Plains region (see the region map in Lockwood and Freeman ). A map of North American Breeding Bird Survey (BBS) data from 1994-2003 indicates a distribution similar to the TBBA map with relative abundances of 10-30 sparrows per BBS route on the Edwards Plateau, 3-10 along the Oklahoma border in the northern Panhandle and 1-3 in northeast Texas. This sparrow also breeds throughout Oklahoma except the western Panhandle at relative abundances ranging from 3-30 sparrows per route (Reinking 2004, Sauer et al. 2007).
Texas is the southwest corner of the breeding range of the Field Sparrow. The range extends across the Gulf Coast states to the Atlantic Coast, north to southern Maine and west to eastern Montana. In winter the most northern breeders move south as far as the Gulf Coast, Texas and extreme northeast Mexico (Carey et al. 1994, Howell and Webb 1995, Sauer et al. 2007).
SEASONAL OCCURRENCE. Resident Field Sparrows breed in Texas within the areas shown on the TBBA map below from late March to late July based on egg collection dates from April 6 to July 10. Fall migrants are common to uncommon as they arrive from late September to early November to winter throughout most of the state. The uncommon to common winter visitors depart from mid-March to early May (Oberholser 1974, Lockwood and Freeman 2004).
BREEDING HABITAT. Field Sparrows breed in Texas between 90 and 700 m (300-2300 ft) in old fields partly overgrown with small trees and shrubs. On the Edwards Plateau they are found in cleared areas in juniper-oak habitat (Oberholser 1974). In Oklahoma these sparrows prefer weedy fields, pastures, prairie/woodland edges, roadsides and woodland openings (Reinking 2004). Along the east edge of Colorado in areas most similar to the Texas Panhandle, atlasers found breeding evidence in riparian deciduous woodlands (50%), rural farmyards and shelter-belts, sagebrush and stream-side willows or tall grass (Nelson 1998).
Females build cup-shaped nests, early ones on the ground or low in a thick shrub or small tree, later ones as high as 1.2 m (4 ft) above ground. Nests are primarily coarse grass outside, lined with fine grass, rootlets and hair, with an outside diameter of about 13 cm (5 in), height of 6.4 cm (2.5 in), inside diameter of 5 cm (2 in) and cup depth of 3.8 cm (1.5 in). The female usually lays 3-4 smooth, creamy white eggs, spotted with reddish brown to pale purple markings. The female incubates the eggs for 11-12 days and the nestlings leave the nest 7-8 days after hatching to be fed by the parents near the nest for the next 2-3 days. Brood parasitism by Brown-headed Cowbirds (Molothrus ater) varies widely (as high as 80%) and pairs may attempt as many as 4 broods per season (Harrison 1979, Carey et al. 1994).
STATUS. Field Sparrows are considered uncommon residents in the areas on the TBBA map with the denser concentrations of breeding sites (Lockwood and Freeman 2004). Comparison of Oberholser’s (1974) map with the TBBA map suggests the range of Field Sparrows in Texas has probably not changed drastically since historic times. The much greater number of breeding sites on the TBBA map is difficult to understand in comparison with the annual population change for 1980-2006. Data derived from 50 BBS routes produced a statistically significant -5.0% trend, even more negative than the survey-wide trend of -2.3% and much worse than the trend for Oklahoma of about +1.2% (Sauer et al.2007). Possibly previous observers, not working under systematic protocols such as those of the TBBA or BBS, overlooked breeding evidence for this species.. Casual observers also may pay too little attention to documenting the status of fairly common, visually inconspicuous species in a state with many more interesting species. However a negative trend of this size is always disturbing and needs further investigation. Text by Robert C. Tweit (2008)
Carey, M., D. E. Burhans and D.A. Nelson. 1994. Field Sparrow (Spizella pusilla). In The birds of North America, No. 103 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Oberholser, H. C. 1974. The bird life of Texas, University of Texas Press, Austin.
Sauer, J. R., J. E. Hines, and J. Fallon. 2007. The North American breeding bird survey, results and analysis 1966-2006. Version 7.23.2007. USGS Patuxent Wildlife Research Center, Laurel MD < http://www.mbr-pwrc.usgs.gov/bbs>