The Long-billed Thrasher is a resident of south Texas and northeastern Mexico. Because it nests in dense vegetation and forages on the ground under cover, nests can be difficult to locate. The low proportion of confirmed nesting records in the TBBA file for this species reflects the difficulties of nest finding. The probable records may represent equally valid nesting observations.
The Long-billed Thrasher closely resembles its nearest relative, the migratory Brown Thrasher (T. rufum), whose winter range in southern Texas partly overlaps the breeding territory of the Long-billed Thrasher. The breeding ranges of these species do not overlap, excluding extralimital breeding records. The Brown Thrasher breeds in the northeastern part of the state, north of the 29th parallel (Freeport), and extending west along the Red River into the Panhandle. Since these two similar species can be confused, birds of either species involved in extralimital breeding records should be carefully identified. See Tweit (1997) and Pyle (1997) for details on identification.
DISTRIBUTION: The highest breeding density in Texas of Long-billed Thrashers is in the lower Rio Grande valley with 55% of the 173 breeding records in the TBBA file from 1987-1992 found in latilongs south of the 27th parallel (roughly San Ignacio). Of 94 Texas Long-billed Thrasher egg sets in the Western Foundation of Vertebrate Zoology (WFVZ) collection, 75 were obtained in Cameron County (Brownsville). Most other breeding records are found in the area between the Rio Grande and a line from Del Rio to San Antonio and on to Rockport (TBBA data and Oberholser 1974). A few probable breeding records in the TBBA file are from Presidio and Midland counties. A sight record and specimen from Colorado (Kingery 1993) are the only United States reports from outside Texas. In Mexico, the species range extends south to Veracruz on the Gulf Coastal plain (Howell and Webb 1995).
SEASONAL OCCURRENCE: Adult Long-billed Thrashers are permanent residents on their breeding territory (Fischer 1980). Nesting starts in mid-March (earliest egg set from WFVZ collected March 15) and runs through June (late WFVZ date, June 17; Tweit 1997). Most nests, 54% of WFVZ sets, are found in May with another 36% in April. Reports of birds outside the breeding range (Kingery 1993) may be vagrant juveniles. The presence of Long-billed Thrashers in winter at Welder Wildlife Refuge near Sinton, and their apparent disappearance at the start of the breeding season (Fischer 1981) suggests further study of seasonal movements of this species is needed.
BREEDING HABITAT: In Texas, the preferred breeding habitat for Long-billed Thrashers is dense undergrowth in woodland along rivers and streams. Typical plants include bottomland willow, mesquite and huisache. Nests are also found in thickets, hedges, shrubs or low trees, 1.2-2.4 m (4-8 ft) above ground or in cactus or yucca. (Oberholser 1974). Colima (Zanthoxylum fagara) is a common nest site (Fischer 1980). The nest is a bulky bowl of twigs, pieces of vines, rootlets, straw and coarse woody stems, lined with fine roots, grasses, bark and Spanish moss (Oberholser 1974).
The modal clutch size in the WFVZ collection is 4 eggs per nest (range 2-5). The eggs are indistinguishable from those of the Brown Thrasher (Harrison 1979). The incubation period in south Texas is 13-14 days and eggs usually hatch over a period of at least 24 hours. Young remain in the nest for 14 days (Fischer 1980).
STATUS: The Long-billed Thrasher is most common in the dense woodland along the lower Rio Grande River. More than half of the TBBA records are from these few latilong blocks. Conversion of woodlands to farm fields in the lower Rio Grande valley has probably reduced the number of breeding pairs. Habitat loss has been extensive in the valley; 95% of brushland was converted to agricultural use, mostly between the mid-1930’s and the 1970’s (Jahrsdoerfer and Leslie 1988). Bent (1948) found Long-billed Thrashers abundant near Brownsville in 1923 as had Sennett (1878).
Woodland remnants found in areas such as Santa Ana National Wildlife Refuge and Bentsen-Rio Grande State Park may have densities reflecting those once found throughout the valley. Bird finding guides and local checklists suggest the Long-billed Thrasher is common in these places. It is apparently less common in other parts of its range in Texas, possibly because these areas are less than optimum habitat.
Current estimates of population density (Lockwood and Freeman 2004) are common to uncommon in South Texas Brush Country.
Text by Robert C. Tweit (2006)
Bent, A. C. 1948. Life histories of North American nuthatches, wrens, thrashers and their allies. U.S. Natl. Mus. Bull. No. 195.
Fischer, D. H. 1980. Breeding biology of Curve-billed Thrashers and Long-billed Thrashers in southern Texas. Condor 82: 392-397.
Fischer, D. H. 1981. Wintering ecology of thrashers in southern Texas. Condor 83: 340-346.
Howell, S. N. G. and S. Webb. 1995. A guide to the birds of Mexico and northern Central America. Oxford University Press, New York.
Jahrsdoerfer, S. E. and D. M. Leslie, Jr. 1988. Tamaulipan brushland of the lower Rio Grande Valley of south Texas: description, human impacts, and management options. U. S. Fish and Wildlife Service Biological Report 88(36).
Kingery, H. E. 1993. Long-billed Thrasher winters at Chatfield. C. F. O. Journal 27: 133-136.
Lockwood, M. W. and B. Freeman. 2004. The TOS handbook of Texas birds. Texas A&M University Press, College Station.
Oberholser, H. C. 1974. The bird life of Texas. University of Texas Press, Austin.
Sennett, G. B. 1878. Notes on the ornithology of the lower Rio Grande of Texas. Bull. U.S. Geological Geographical Survey 4: 1-66.
Tweit, R. C. 1997. Long-billed Thrasher (Toxostoma longirostre). In The birds oh North America, No. 317 (A. Poole and F. Gill, eds.). The Birds of North America, Inc. Philadelphia, PA.