Empidonax virescens
The bird with the distinctive nest, the Acadian Flycatcher provides atlasers with a much better clue to its identity than is usual for an Empidonax flycatcher. It is also the only member of this genus breeding in east and central Texas. In contrast to wood-pewees who camouflage their nests to look like lichen-covered knobs, the hammock-like nest of the Acadian Flycatcher is decorated with long streamers of plant material, easily visible from below. The contents, eggs or nestlings, may also be visible from below as the nest structure is often thin.(Harrison 1979, Whitehead and Taylor 2002).
With experience and care, Empidonax flycatchers can be distinguished by their simple vocalizations much more easily than by their very similar visual appearances. The Acadian Flycatchers nest, however, is a treat for atlasers, because the nest is not only much more conspicuous but also easily identifiable.
Acadian Flycatchers breed in many woodland habitats, but are most successful in larger blocks of undisturbed forest where they are less threated by predators and brood parasitism by Brown-headed Cowbirds (Molothrus ater; Oberholser 1974,Whitehead and Taylor 2002).
DISTRIBUTION. During the 1987-1992 field work of the TBBA project, atlasers found breeding evidence for Acadian Flycatcher to be most common in the Pineywoods, Edwards Plateau, and the eastern Coastal Prairies regions defined by Lockwood and Freeman (2004). Additional scattered records were found in the Post Oak Savannah and Blackland Prairie region. This distribution is consistent with the map derived from North American Breeding Bird Survey (BBS) data which shows relative abundances of 1-3 flycatchers per 40 km (25 mi) BBS route in the Pineywoods and eastern Coastal Prairies regions and <1 in the Edwards Plateau and eastern Post Oak Savannah and Blackland Prairie regions (Sauer et al 2005).
Outside Texas Acadian Flycatchers breed from east Iowa across the southern Great Lakes region and on to Cape Cod, Massachusetts. The range extends south to eastern Oklahoma, the Gulf Coast and north Florida. The species winters from the Gulf shore of Nicaragua south through Costa Rica and Panama to north and west Colombia, northwest Venezuela and west Ecuador (Whitehead and Taylor 2002).
SEASONAL OCCURRENCE. Acadian Flycatchers arrive in Texas from March 17 to May 22, primarily between mid-April and mid-May and return south from July 15 to December 8 with most movement occurring between early August and mid-September. Breeding takes place between early May and late July; egg dates May 9 to July 11 (Oberholser 1974).
BREEDING HABITAT. Acadian Flycatchers breed in Texas from sea level to 600 m (2000 ft) in baldcypress swamps and oak thickets along creeks and in valleys. The Big Thicket is typical of preferred habitats (Oberholser 1974).
The female builds the frail, saucer-shaped basket, swung like a hammock, between two twigs of a slender low limb of a large tree. The structure is usually far out from the trunk, shaded by overhead leaves at 2.5-6 m (9-20 ft) above ground. It is built of fine, dry plant stems, plant fibers, tendrils, and catkins. The slight lining is composed of grass stems, rootlets, plant down and spider silk. The nest is always decorated with long streamers of dry grasses, grapevine and other material which hang down from the nest 0.3-0.7 m (1-2 ft), giving a trashy appearance from below. The outside diameter of the nest is 9 cm (3.5 in), inside diameter 4 cm (1.5 in), cup depth 2.5 cm (1 in). The nest is unique.
The female usually lays 3 (range 2-4) creamy to buffy white, smooth eggs with almost no gloss. She incubates the single brood for 13-14 days. Nestlings leave the nest 12-18 days after hatching (Harrison 1979, Whitehead and Taylor 2002).
STATUS. Lockwood and Freeman (2004). describe Acadian Flycatcher as a common migrant and summer resident in the eastern third of Texas and a locally uncommon summer resident in the Edwards Plateau region west to the Devils River drainage.
Data from the 25 BBS routes on which this species was detected in Texas produced a 95% trend estimate (There is a 95% chance that the actual population trend will be between these two numbers.) of -4.1 to 3.0% population change per year for the period 1966-2004. Nationally the data from 921 routes provided a 95% confidence interval of -0.5 to 0.3% for the same period (Sauer et al. 2005). These relatively small changes are reassuring for the future of Acadian Flycatcher as a breeder and migrant in Texas.
Text by Robert C. Tweit (2005).
Literature cited.
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.
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 1966-2004. Version 2005.1. USGS Patuxent Wildlife Research Center, Laurel MD (Web site, http://www.mbr-pwrc.usgs.gov/bbs).
Whitehead, D. R. and T. Taylor. 2002. Acadian Flycatcher (Empidonax virescens). In The birds of North America, No.614 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.