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Ammodramus maritimus
The taxonomy of the birds now known as Seaside Sparrows has a confusing history. These mostly sedentary individuals live in coastal marshes which are often separated from each other. The separation allows the evolution of distinct populations, which have been recognized as varying numbers of species and subspecies. Currently all “Seaside Sparrows” are considered a single species with three groups of subspecies: the extinct Dusky Seaside Sparrow (Ammodramus maritimus nigrescens), the threatened Cape Sable Sparrow (A. m. mirabilis) and everything else (A. m. maritimus; Am. Ornithol. Union 1998). Rising (2005) provides a scathing review of this classification’ and covers the evidence suggesting that the Atlantic Coast populations south to northeast Florida constitute one species, the Gulf Coast sparrows from northwest Florida through the Texas coast are another species and the remaining Florida populations need further study.
DISTRIBUTION: During the 1987-1992 field work seasons of the TBBA project, atlasers found 3 blocks with confirmed breeding evidence, 15 with probable breeding and 6 with possible breeding for Seaside Sparrows along the coast in the Coastal Prairies, Coastal Sand Plain and South Texas Brush Country eco-regions (see the eco-region map in Lockwood and Freeman [2004]).
Seaside Sparrows also breed along the Gulf and Atlantic coasts from Louisiana to New Hampshire with the exception of the central and south coasts of Florida. Some northern birds move south in the breeding range in the winter (Post and Greenlaw 1994, Am. Ornithol. Union 1998).
SEASONAL OCCURRENCE: Seaside Sparrows are resident along the Texas coast. They breed from early April to late July, based on egg collection dates from April 15 to July 4 (Oberholser 1974, Lockwood and Freeman 2004).
BREEDING HABITAT: Seaside Sparrows breed at or near sea level along the Texas coast in tall Spartina grass, rushes and reeds growing in brackish or salt water in tidal marshes. The open-cup nests are built by the female of grass stems and lined with finer grasses. She places her nest on the ground, a few centimeters above high tide level, concealed by tall grass or other vegetation, or low in a shrub. Alternatively the nest may be domed with a side entrance (Oberholser 1974, Harrison 1979, Post and Greenlaw 1994).
In this structure the female usually lays 4 (range 2-6) smooth, blueish white to greenish white eggs, speckled and blotched with shades of brown. She lays one egg per day and incubates them for about 12 days. Both parents feed the young who normally leave the nest 9-11 days after hatching to join small groups of individuals who gradually move away from the nest site (Post and Greenlaw 1994).
STATUS: Seaside Sparrows are uncommon to locally common on the upper coast south to Aransas County and rare and local further south (Lockwood and Freeman 2004). Since only three North American Breeding Bird Survey routes in Texas observed these sparrows, the suggested annual population change for 1980-2007 of -5.3% (Sauer et al. 2008) is probably not reliable. Closer monitoring of this habitat specialist, threatened by major storms and chemical contamination, would provide a more meaningful view of its present status. Text by Robert C. Tweit (2009)
Literature cited
American Ornithologists’ Union. 1998. Checklist of North American birds, 7th ed. Am, Ornithol. Union, Washington, DC.
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.
Rising, J. D. 2005. Ecological and genetic diversity in the Seaside Sparrow. Birding 37: 490-496.
Sauer, J. R., J. E. Hines, and J. Fallon. 2007. The North American breeding bird survey, results and analysis 1966-2006. Version 7.23.2007. USGS Patuxent Wildlife Research Center, Laurel MD < http://www.mbr-pwrc.usgs.gov/bbs>