American Oystercatchers are one of at least 10 species in this worldwide genus (Monroe and Sibley 1993). These large, conspicuous and vociferous shorebirds with their black and white plumage and stout, red bills, are even more spectacular in flight. American Oystercatchers are most easily identified on mudflats as they probe for prey items. Their loud kleep or peep contact calls, used by both sexes are distinctive (Nol and Humphrey 1994).
American Oystercatchers are among the few avian predators to forage on oysters, clams, mussels, sandworms, limpets, jellyfish, sea urchins, starfish and crabs. Preferred foraging sited include inter-tidal sand or mudflats (especially along the edge of receding tides), oyster or mussel reefs and shoals. They also forage less commonly on rocky shorelines. These birds also feed in shellfish beds while mussels or oysters are still submerged, using the sharp edges of their stout bills to separate these animals from their protective shells (Nol and Humphrey 1994).
DISTRIBUTION. During the 1987-1992 field work seasons of the TBBA project, atlasers found 10 confirmed, 4 probable and 8 possible breeding sites for American Oystercatchers along the coast in the Coastal Prairies, Coastal Sand Plain and South Texas Brush Country regions (see the region map in Lockwood and Freeman ). They also breed in appropriate habitat along the Atlantic and Gulf coasts from Massachusetts to the Yucatan Peninsula of Mexico. Breeding also occurs on the Pacific coast of Mexico from Baja California to Guerrero, in the West Indies, southern Central America and on the coasts of South America to Chile and Argentina. In winter many breeders on the Atlantic Coast of the United States move southward (Stiles and Skutch 1989, Nol and Humphrey 1994, Howell and Webb 1995, Am. Ornithol. Union 1998).
SEASONAL OCCURRENCE. American Oystercatchers are year-round residents on the Texas coast. They breed from February to mid-July, based on young as early as March 17 and eggs as late as June 10 (Oberholser 1974, Lockwood and Freeman 2004).
BREEDING HABITAT. American Oystercatchers breed in Texas just above sea level on higher parts of sandy beaches (Oberholser 1974). Using his feet, the male scrapes out 5 or more hollows in sand or shell fragments. In one of these the female lays 2-3 (range 1-6), buff to olive-buff eggs, marked and overlaid irregularly with light to dark brown spots and blotches (see photo in Harrison ). Both sexes share incubation duties for about 27 days (Harrison 1979, Nol and Humphrey 1994)..
The precocial young can run shortly after hatching, but are dependent on their parents for food for at least 60 days. Only one brood is raised per season. Young do not breed until 3-4 years old. A wild American Oystercatcher at least 17 years old has been reported (Nol and Humphrey 1994). This longevity apparently allows these birds the luxury of a low rate of reproduction.
STATUS. American Oystercatchers are locally common along the central coast and rare to locally uncommon on the upper and lower coasts (Lockwood and Freeman 2004). These shorebirds show similar distributions on the TBBA map and that in Oberholser (1974), suggesting no drastic change in distribution has occurred in recent years.
As with other shorebirds, habitat degradation and human disturbance of nesting pairs are major problems for American Oystercatchers, especially because they tend to re-occupy the same territories in consecutive years (Nol and Humphrey 1994). Other more recently recognized threats to the Texas population include rising sea levels and more frequent and severe hurricanes.
Text by Robert C. Tweit (2008)
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.
Monroe, B. L., Jr. and C. G. Sibley. 1993. A world checklist of birds. Yale University Press, New Haven, CT.
Nol, E. and R. C. Humphrey. 1994. American Oystercatcher (Haematopus palliatus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from: http://bna.birds.cornell.edu/bna/species/082
Oberholser, H. C. 1974. The bird life of Texas. University of Texas Press, Austin.
Stiles, F. G. and A.. F. Skutch. 1989. A guide to the birds of Costa Rica. Cornell University Press, Ithaca, NY.