The saga of the Lark Sparrow in North America is closely associated with the changes in American agriculture in the last 300 years. As eastern forests were cleared for fields and pastures, the breeding range of this species expanded eastward from the Great Plains to the Allegheny Mountains. As agriculture in the east changed in the past century and many grassy pastures disappeared, Lark Sparrows declined or disappeared in some areas (Martin and Parrish 2000, Sauer et al. 2004).
DISTRIBUTION. During the 1987-1992 TBBA field work atlasers found Lark Sparrows breeding almost everywhere in Texas with the exception of the Coastal Prairies and southern Pineywoods regions of Lockwood and Freeman (2004). In the Trans-Pecos breeding is more scattered.
Elsewhere Lark Sparrows breed most commonly in north central Utah, southwestern Montana, northern and southwestern Wyoming, western Nebraska, southeastern Colorado,eastern New Mexico, western Oklahoma and the highlands of northern Mexico. The species also breeds widely, but in lower densities in the remainder of the United States and Canada (Sauer et al. 2004).
In winter Lark Sparrows are found along the Pacific Coast in California and Baja California Sur, the lower Colorado River valley, extreme south Arizona and New Mexico, the breeding area of the species in Texas (except for the Panhandle) and the mainland of Mexico south to the Isthmus of Tehuantepec (Martin and Parrish 200).
SEASONAL OCCURRENCE. In Texas Lark Sparrows are year-round residents in much of the state, breeding from early March to early September; egg clutches have been collected from March 30 to August 18. TBBA observers found sparrows building nests from March 31 to July 28, nests with eggs from May 26 to July 4, adults feeding young birds or carrying fecal sacs from April 27 to July 24 and recently fledged young from April 3 to August 13. June and July appear to be the peak of the breeding season with most reports of feeding activity (22) evenly split between these two months. Most recently fledged young were found in June (more than 50% of the total).
Between mid-October and mid-March the species is common in the southern third of Texas, and uncommon in the northern two-thirds of the state, but rare or absent from the northern Panhandle (Oberholser 1974).
BREEDING HABITAT. Lark Sparrows breed in Texas from sea level to 1900 m (6300 ft). Within this elevational range the
species prefers savannas with scattered mesquite or oak trees and patches of grasses, forbs, cultivated grain and bare ground. Lark Sparrows also breed in foothills with oak and juniper, open grasslands and grassy openings in pine woods. The nest, built by the female in 3-4 days, is placed on the ground, in trees or bushes or even on a structure. Ground nests are concealed in grass or under bushes.
Nests are constructed of dry grass, plant stalks, rootlets, bark strips, twigs and human detritus such as string. Lark Sparrow nests are lined with leaves, rootlets and animal hair. The female usually lays 4-5 (range 3-6) white (sometimes tinted brownish or bluish) eggs, incubated by the female for 11-12 days. Nestlings typically leave the nest 11-12 days after hatching. Two broods are possible; some males may have 2 mates within their territory. Lark Sparrows are frequent hosts to Brown-headed Cowbird (Molothrus ater) eggs (Oberholser 1974, Harrison 1979, Martin and Parrish 2000).
STATUS. Lockwood and Freeman (2004) consider Lark Sparrow a common to uncommon migrant and summer resident in most of Texas. Abundance data from North American Breeding Bird Survey (BBS) routes indicate the species is most common in breeding season in the northern Panhandle, Rolling Plains, Edwards Plateau and South Texas Brush Country regions. Here an average of 10-30 Lark Sparrows were detected per 40 km (25 mi) BBS route in 1994-2003. Average numbers decreased in all directions from these regions. Less than 3 sparrows were found per route in the northern Pineywoods, southern High Plains and Big Bend National Park area and extreme west Texas (Sauer et al. 2004).
Trend data from the 166 BBS routes in Texas on which Lark Sparrows were observed show a statistically significant population change of -3.8% per year for the period 1966-2003. Across the United States and Canada, data from 1099 routes produced a trend of -2.9% per year (Sauer et al. 2004). The Texas trend suggests the 2003 population for the state is only around 25% of its size in 1966.
The BBS trend for Texas is disturbing for the future of this widespread breeding bird in Texas; especially since the BBS distribution map suggests Texas contains an even higher proportion of the North American breeding population than is suggested by the ratio of Texas BBS routes reporting Lark Sparrows to the survey total. Text by Robert C. Tweit (2004)
Harrison, H. H. 1979. A field guide to western birds’ nests. Houghton Mifflin, Boston, MA.
Lockwood, M. W. and B. Freeman. 2004. The TOS handbook of Texas birds. Texas A&M University Press, College Station.
Martin, J. W. and J. R. Parrish. 2000. Lark Sparrow (Chondestes grammacus). In The birds of North America, No. 488 (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. 2004. The North American Breeding Bird Survey, results and analysis 1966-2003. Version 2004.1. USGS Patuxent Wildlife Research Center, Laurel MD (Web site, http://www.mbr-pwrc.usgs.gov/bbs).