This small, drab warbler, primarily a summer resident of the Sonoran Desert, is most common in groves of old mesquite (bosques) which provide excellent nesting and foraging sites for this cavity-nesting, insectivorous species. Most of these bosques have been cut for firewood and their usual sites along flowing streams have been cleared for agriculture. Fortunately Lucy’s Warblers have adapted to what were once probably marginal habitats, but the loss of the old mesquite bosques as well as cottonwoods and willows has probably reduced populations considerably since the mid-1800’s (Oberholser 1974, Corman 2005).
DISTRIBUTION. During the 1987-1992 field work seasons of the TBBA project, observers found a confirmed record in latilong 29103, quad B6, two probable records in 30104-A6 and 30105-A5 and 3 possible records, two in 30104-B6 and the other in 29104-E3, all near the Rio Grande River from Hudspeth County to Brewster County in the Trans-Pecos.
Lucy’s Warbler breeds primarily in south and central Arizona below the Mogollon Rim and in northern Sonora, Mexico. Breeding also occurs in the Colorado River drainage in southeast California, southern Nevada, northern Arizona, southern Utah, southwest New Mexico and northwest Chihuahua.The species winters along the west coast of Mexico from south Sonora to Oaxaca (Howell ans Webb 1995, Johnson et al.1997, Corman 2005).
SEASONAL OCCURRENCE. Lucy’s Warb- lers arrive in Texas around mid-March and depart about mid-September. Too little data are available to delineate the Texas breeding season (Oberholser 1974, Lockwood and Freeman 2004), but in Arizona atlasers found almost all breeding evidence was from April 1 to June 31 (Corman 2005).
BREEDING HABITAT. In Texas Lucy’s Warbler breeds primarily in riparian habitat near the Rio Grande River west from Big Bend (Oberholser 1974, Lockwood and Freeman 2004). In Arizona atlasers found 55% of breeding evidence in Sonoran Desert riparian habitats (dry washes and flowing streams) and 19% in Sonoran Desert non-riparian habitats (Corman 2005).
This warbler nests in cavities including old woodpecker holes in trees or large cacti, behind loose tree bark, in old Verdin nests or among tree roots exposed on a riverbank. The female builds a cup of twigs, forb stems, straw, leaves and mesquite leaf stems and flowers clusters in the cavity. The usual clutch is 4-5 (range 3-7) white eggs finely marked with brick or mahogany red spots, often in a wreath at the large end. The length of the incubation and nestling periods are not known. Parasitism by Brown-headed Cowbirds (Molothrus ater) may be as high as 30%, but 2 broods per season may not be uncommon (Harrison 1979, Johnson et al. 1997).
STATUS. Lucy’s Warblers are rare to locally uncommon along the upper Rio Grande River in Trans-Pecos Texas (Lockwood and Freeman 2004). The two North American Breeding Bird Survey routes on which this species was detected in Texas provide too little data for a meaningful population trend. Data from 41 routes in the southwest United States suggest the population of Lucy’s Warbler was stable for the period 1980-2005 (Sauer et al. 2005). Text by Robert C. Tweit (2007)
Lockwood, M. W. and B. Freeman. 2004. The TOS handbook of Texas birds. Texas A&M University Press, College Station.