The loud, varied song of the Carolina Wren is most likely to be the first clue to the presence of this inhabitant of thickets in woodland, parks and gardens as well as more exotic habitats such as cypress swamps. As winters have become milder in recent years, its range has expanded northward and now includes most of the eastern United States.
The status of populations on the Yucatan Peninsula of Mexico and in Guatemala and Nicaragua has been questioned. This race is now considered a separate group (T. albinucha; Cabot’s Wren) by the AOU Checklist of North American birds (Am. Ornithol. Union 1998);, other authors (Phillips 1986, Howell and Webb 1995) consider these birds to be a separate species called White-browed Wren.
DISTRIBUTION. During the 1987-1992 field work seasons of the TBBA project, volunteers found most confirmed breeding records for Carolina Wren in the Pineywoods, Post Oak Savannah and Blackland Prairies, eastern Rolling Plains, eastern Edwards Plateau, Coastal Prairies and Coastal Sand Plain regions (see the region map in Lockwood and Freeman (2004). Further west breeding sites were much more scattered in the Rolling Plains and Edwards Plateau with a few in the High Plains. Records were found at the edges of the South Texas Brush Country.
Data from North American Breeding Bird Survey routes in the eastern United States indicate the primary range (more than one wren detected per route) extends from souther New England and the southern parts of Pennsylvania, Ohio, Indiana and Illinois, Missouri and eastern Kansas south to the Gulf Coast and into northeast Mexico (Howell and Webb 1995, Sauer et al. 2005).
SEASONAL OCCURRENCE. Carolina Wren is a resident species in Texas, breeding from mid-February to late August (based on egg dates from February 26 to August 13; Oberholser 1974). TBBA atlasers found 39 confirmed breeding dates from February 23 (a bird on a nest) to July 26 (recently fledged young).
BREEDING HABITAT. This wren breeds in Texas from near sea level to 1100 m (3500 ft) in a variety of habitats in th eastern part of the state, especially those with thick undergrowth, often near water (Oberholser 1974). This wren is a secondary-cavity nester using natural cavities or woodpecker holes in trees, crevices in stone walls or buildings, nest boxes and even empty flower pots. The generally domed structure, with a side opening, is a mass of leaves, twigs, moss, forb stems, strips of inner bark and debris. It is lined with feathers, fine grasses, moss and hair (Harrison 1979), Haggerty and Morton 1995).
The female generally lays 4 (range 3-7) white to pinkish white eggs, finely spotted with rusty brown. She incubates the eggs for 12-16 days and the young birds leave the nest 10-16 days after hatching. As many as 3 successful broods may be raised in a season. Several studies found about 1/4 of nests parasitized by Brown-headed Cowbirds (Molothrus ater; Haggerty and Morton 1995). A Carolina Wren nest was even parasitized by a House Finch (Carpodacus mexicanus; Wood and Carter 2006).
STATUS. The Carolina Wren is a common to abundant resident in eastern Texas (Lockwood an Freeman 2004). The TBBA map is similar to that of Oberholser (1974), suggesting little change in range occurred in recent times. This conclusion is consistent with BBS data from 89 routes which produce a statistically significant annual population change of +2.4% for the 1980-2005 period. Oklahoma and Louisiana trends are of similar magnitude (Sauer et al. 2005). This data is definitely encouraging for the future of this wren in Texas.
Text by Robert C. Tweit (2007)
Haggerty, T. M. and E. S. Morton. 1995. Carolina Wren (Thryothorus ludovicianus). In The birds of North America, No. 188 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
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.
Oberholser, H. C. 1974. The bird life of Texas. University of Texas Press, Austin.
Phillips, A. R. 1986. The known birds of North and Middle America, Part 1. A. R. Phillips, Denver, CO.
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>
Wood, D. R. and W. A. Carter. 2006. Carolina Wren nest successfully parasitized by House Finch. Wilson J. Ornithol. 118: 413-415.