Blue-gray Gnatcatchers, little gray birds with long tails and fussy sounds, are widespread in the United States and Mexico and the only gnatcatchers in eastern North America. In their brushy habitats they glean insects from plant foliage, sometimes while hovering, and may also sally forth from a perch to catch small prey in flight. Three other species of gnatcatchers are found in the southwestern United States and at least 7 other species in Cuba and Central and South America (Ellison 1992, Monroe and Sibley 1993).
DISTRIBUTION. During the 1987-1992 field work seasons of the TBBA project, observers found the thickest concentrations of confirmed breeding records in the Pineywoods and eastern Post Oak Savannah regions, becoming more scattered on the Rolling Plains and Edwards Plateau with only a few on the High Plains, Coastal Prairies and Coastal Sand Plain and South Texas Brush Country. In the Trans-Pecos, confirmed breeding was recorded in the Guadalupe Mountains and the Big Bend area (see the region map in Lockwood and Freeman ).
This species is a spring and fall migrant throughout this state and a winter resident in south Texas, along the coast and in the southern Trans-Pecos (Lockwood and Freeman 2004).
North American Breeding Bird Survey (BBS) data show most Blue-gray Gnatcatchers breeding in the southeastern United States from Maryland, the Virginias, Kentucky, southern Missouri and eastern Oklahoma south to northern Florida and the Gulf Coast. Other populations breed from northwest Colorado across Utah to southern Nevada and along the California coast. The species is resident through most of Mexico and Belize; migrants from the United States winter through the lowest elevations of the southwest United States, Mexico, Belize, Guatemala and Honduras (Ellison 1992, Howell and Webb 1995, Sauer et al. SEASONAL OCCURRENCE. Blue-gray Gnatcatchers arrive in Texas from February 28 to May with most present from mid-March to mid-April. Breeding occurs from late March to late July, based on egg dates from April 4 to July 3. Migrants move south between July and November 24 with most passing through from mid-August to mid-October (Oberholser 1974, Lockwood and Freeman 2004).
BREEDING HABITAT. In Texas this species breeds from near sea level to about 2300 m (7500 ft) in oaks (Oberholser 1974). Gnatcatchers in Oklahoma nest in oaks and also in mixed forests, riparian areas and wooded swamps (Gall 2004). In Arizona and Colorado pinyon-juniper is the most common habitat for this species and may also be used by blue-grays in the Trans-Pecos as well (Versaw 1998, Wise-Gervais 2005).
The nest is a neat compact cup built of forb and grass stems and bark strips, covered with spider and insect silk and lichens. It is saddled on a horizontal limb, usually more than half way from the trunk to the tip or attached to a fork in a branch. In eastern North America, height above the ground is variable ranging from 0.8-24 m (3-75 ft) with a mean of 8.5 m (28 ft). In the nest, built by both sexes in 1-2 weeks and lined with plant down, feathers and other fine materials, the female usually lays 4-5 (range 2-6) pale blue to bluish-white eggs, sparingly marked with small reddish dots (see Harrison  for a photo of markings). The eggs hatch after 11-15 days of incubation and the young leave the nest at least 9 days later. Few pairs attempt a second brood. Brood parasitism by Brown-headed Cowbirds (Molothrus ater) are as high as 82% (Harrison 1979. Ellison 1992).
STATUS. The breeding and summer distribution on the map in Oberholser (1974) is generally similar to the TBBA nap below. Lockwood and Freeman (2004) describe Blue-gray Gnatcatcher as a rare to locally common summer resident in eastern Texas, except the south. This gnatcatcher also breeds in the Guadalupe and Chisos mountains. BBS data from 1980-2006 obtained from 83 routes in this state on which this species was detected, suggest a trend of about -2.2% population change per year (Sauer et al. 2005)m
Text by Robert C. Tweit (2006)
Ellison, W. G. 1992. Blue-gray Gnatcatcher (Polioptila caerulea). In The birds of North America, No. 23 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Gall, B. L. 2004. Blue-gray Gnatcatcher (Polioptila caerulea) In Oklahoma breeding bird atlas pp. 324-325 (D. L. Reinking ed.). University of Oklahoma Press, Norman.
Harrison, H. H. 1979. A field guide to western birds’ nests. Houghton Mifflin, Boston, MA.
Howell, S. N. G. and S. Webb. 1995. A guide to the birds of Mexico and northern Central America. Oxford University Press, New York.
Lockwood, M. W. and B. Freeman. 2004. The TOS handbook of Texas birds. Texas A&M University Press, College Station.
Monroe, B. L., Jr. and C. G. Sibley, 1993. A world checklist of birds. Yale University Press, New Haven, CT.
Oberholser, H. C. 1974. The bird life of Texas. University of Texas Press, Austin.
Sauer, J. R., J. E. Hines, and J. Fallon. 2005. The North American Breeding Bird Survey, results and analysis 1966-2005. Version 6.2 2006. USGS Patuxent Wildlife Research Center, Laurel MD < http://www.mbr-pwrc.usgs.gov/bbs>
Versaw, A. E. 1998. Blue-gray Gnatcatcher (Polioptila caerulea). In Colorado breeding bird atlas, pp. 380-381 (H. E. Kingery, ed.). Colorado Bird Atlas Partnership, Denver.
Wise-Gervais, C. 2005. Blue-gray Gnatcatcher (Polioptila caerulea). In Arizona breeding bird atlas. pp. 422-423 (T. E. Corman and C. Wise-Gervais, eds.), University of New Mexico Press, Albuquerque.