The Black-headed Grosbeak is another species breeding in Texas primarily or exclusively in the mountains at the highest elevations in the state. Elsewhere the species breeds in a variety of woodland habitats at a wide range of elevations across much of the western United States and southwestern Canada.
Black-headed Grosbeaks have several characteristics which can create problems for atlasers. The species is strongly sexually dimorphic (Adult male and female plumages differ markedly). Males do not acquire full adult plumage until their second fall molt. In their first possible breeding season, males can have any of a variety of plumages from female-like to one similar to adult males. Few of these young males can defend a territory successfully. Non-territorial males lacking adult plumage avoid aggressive responses from territorial males as the young birds move through established territories (hill 1995).
Males in sub-adult plumage tend to migrate later than those in adult plumage. This difference may explain “possible breeding” records in non-breeding areas. See Hill (1995) and Pyle (1997) for plumage details.
Both male and female Black-headed Grosbeaks sing and sometimes sing from the nest as they share incubation duties.. Males also assist in feeding nestlings and their presence near the nest may aid atlasers (Hill 1995).
DISTRIBUTION. During the 1987-1992 TBBA project field work,surveyors found most breeding records of the Black-headed Grosbeak in the mountains of the region and along the Rio Grande River west of Big Bend National Park.
A few additional confirmed records are from the Panhandle with two probable records from the Edwards Plateau area.
Outside Texas the species breeds from British Columbia to southwestern Manitoba, south between the Pacific Coast and the Missouri River, eastern Nebraska, western Kansas, and western New Mexico. The range extends south through the highlands of Mexico to the Isthmus of Tehuantepec. Within this area the species is absent from lowlands of southern California and western Arizona and prairie areas of eastern Colorado, Nebraska and Kansas. Black-headed Grosbeaks winter in Mexico in Baja California Sur and on the mainland from Sinaloa and Tamaulipas south to the Isthmus of Tehuantepec (Hill 1995).
SEASONAL OCCURRENCE. In spring Black-headed Grosbeaks migrate through Texas between early April and late May and breed from early May to late July with egg dates between May 21 and June 17. TBBA atlasers found recently fledged young near a nest in July. The species returns south between early August and late October (Oberholser 1974, Lockwood and Freeman 2004).
BREEDING HABITAT. In Texas Black- headed Grosbeaks breed at elevations between 1100 and 2400 m (3700 to 8000 ft). At the upper end of its elevational range the species nests in pine, pine-oak and pinyon- juniper associations. Within riparian areas it is found in cottonwoods and willows throughout its elevational range. At lower elevations the species sometimes overlaps the breeding range of Blue Grosbeak (Passerina caerulea; Oberholser 1974).
The nest is placed in a fork of a tree or bush about 3 m (10 ft) above ground. The female builds the nest in 3-4 days. A rather loosely constructed saucer, it has a very shallow depression for eggs. The nest contains a few thin twigs, grasses, roots, plant stalks, and leafy twigs. It is lined with rootlets and other fine materials. The outside diameter averages 14 cm (5.5 in), height and inside diameter 8 cm (3 in) and cup depth 4.5 cm (1.8 in). The nest of the Black- headed Grosbeak is sometimes so thin that the contents can be seen from below
The female usually lays 3 (range 2-5) bluish or greenish eggs (indistinguishable from the eggs of Rose-breasted Grosbeak [Pheucticus ludovicianus]). Both sexes incubate and sing on the nest during daylight hours. The incubation period is 12-16 days and nestlings fledge between 10 and14 days old (Oberholser 1974, Harrison 1979, Hill 1995).
STATUS. Lockwood and Freeman (2004) characterize Black-headed Grosbeak as a common migrant and summer resident in the mountains of Texas, and a casual summer visitor in the Panhandle. The species is an uncommon to rare migrant throughout the lower elevations of the region, the High Plains, northern Rolling Plains, western Edwards Plateau and south to the lower Rio Grande River valley. Black-headed Grosbeak becomes increasingly rare further east.
Breeding Bird Survey (BBS) data from the three 40 km (25 mi) routes in Texas on which Black- headed Grosbeaks were detected had an average of 1-3 grosbeaks per route in the area of the Davis and Guadalupe mountains and <1 individual per route around Big Bend National Park (Sauer et al. 2004).
The TBBA map is quite similar to Oberholser’s (1974) map of Texas. Oberholser did not record breeding outside this area, but showed a summer record for the Edwards Plateau and several in and near the Panhandle.
The BBS data are insufficient to produce a meaningful trend estimate for Texas. Across the United States and Canada data from 569 BBS routes produced a 95% confidence interval (19 times out of 20 the actual trend will be between these figures) for Black-headed d Grosbeak of -0.4 to 1.9% population change per year for the 1966-2003 period. This interval suggests that any population change for this species across its range in the United States and Canada is probably relatively small (Sauer et al. 2004). Text by Robert C. Tweit (2005)
Hill, G. F. 1995. Black-headed Grosbeak (Pheucticus melanocephalus). In The birds of North America, No. 143 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
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, Vol. 2. University of Texas Press, Austin.
Pyle, P. 1997. Identification guide to North American birds, part 1. Slate Creek Press, Bolinas, CA.
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).