American Oystercatcher--BIOLOGICAL AND ECOTOXICOLOGICAL CHARACTERISTICS OF TERRESTRIAL VERTEBRATE SPECIES RESIDING IN ESTUARIES

American Oystercatcher

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Species	Haematopus palliatus is about 43-53 cm in length. Females tend to have a greater mass, 638 grams on average, than males, 567 grams on average (Nol and Humphrey, 1994) Primarily blackish-brown and white, conspicuous features include a red bill, pink feet, and yellow eyes. When in flight, a white wing strip is obvious (Bull and Farrand, 1977).
Status in Estuaries	A solitary ground nester, this species prefers to nest on sandy, pebbly beaches or on borders of salt marshes. A typical clutch would include 2-4 spotted blackish-buff eggs in a shallow scrape lined with a few shell fragments (Bull and Farrand, 1977). Young are precocial (Ehrlich et al., 1988). The maximum age of an American oystercatcher recorded in nature 17 years (Nol and Humphrey, 1994).
Abundance and Range	During the breeding season, oystercatchers occur in coastal areas from Massachusetts south to Argentina and Chile (Bull and Farrand, 1977). During the winter months this species can be found from New Jersey southward (Nol and Humphrey, 1994). Bird counts of Atlantic Coast colonies indicated 2,782 individuals nesting between Florida and Massachusetts. Christmas bird counts estimated 9,062 individuals in 1970 and 1,106 individuals in 1972 (Nol and Humphrey, 1994).
Site Fidelity	Pairs that stay together typically nest in same territory for consecutive years. Winter site fidelity is also suspected (Nol and Humphrey, 1994).
Ease of Census	Moderate. Censussing can be difficult since this species tends to avoid human contact (Nol and Humphrey, 1994).
Feeding Habits	The oystercatcher forages in shallow water by using its bill to probe mud below the surface and feeds almost exclusively on shellfish and marine invertebrates. In the northern range common prey items include blue mussels, ribbed mussels, soft-shell clams, sand worms, razor clams, and hard clams. In the southern range common prey items are oysters, soft-shell and razor clams, ribbed mussels, mole crabs, sand worms, limpets, jelly fish, sea urchin, starfish and crabs (Nol and Humphrey, 1994).

American Oystercatcher Contaminant Exposure Data
I.	Organochlorine Contaminants
1.	One individual collected in South Carolina that was positive for avian cholera, had low levels of DDE (0.45 mg/g in carcass and 0.88 mg/g in ovarian follicle); other organochlorines and PCBs not detected (Blus et al. 1978).
2.	Twenty-eight individuals collected in South Carolina between 1971-75 had low concentration of DDE and total PCBs (geometric means <1 mg/g) (Blus and Lamont, 1979).
II.	Cholinesterase-Inhibiting Pesticides
	No direct exposure data available
III.	Trace Elements, Metals, and Metalloids
	No concentration data available
IV.	Petroleum
	No residue data available
American Oystercatcher Contaminant Response Data
I.	Organochlorine Contaminants
1.	A comparison of pre- and post-DDT era eggshells revealed thinning (4.7%) in Atlantic Coast samples (Morrison et al., 1978).
2.	Mean eggshell thickness in South Carolina samples from 1971-75 was not significantly different from the pre-1947 mean (Blus and Lamont, 1979).
II.	Cholinesterase-Inhibiting Pesticides
	No response data available
III.	Trace Elements, Metals, and Metalloids
	No response data available
IV.	Petroleum
	No response data available
References for American Oystercatcher
Blus, L. J., Locke, L. N. and E. Cromartie. 1978. Avian cholera and organochlorine residues in an American oystercatcher. Estuaries 1:128-129.
Blus, L. J. and T. G. Lamont. 1979. Organochlorine residues in 6 species of estuarine birds South Carolina USA 1971-1975. Pestic. Monit. J. 13:56-60.
Bull, J. and J. Farrand, Jr. 1977. The Audubon Society Field Guide to North American Birds. Alfred A. Knopf, New York. 784 pp.
Dunning, Jr., J.B., ed. 1993. CRC Handbook of Avian Body Masses. CRC Press, Ann Arbor. 371 pp.
Ehrlich, P.R., D.S. Dobkin, and D. Wheye. 1988. The Birder's Handbook. Simon & Schuster, New York. 785 pp.
Morrison, M. L. and L.F. Kiff. 1978. Post-DDT shorebird eggshell thickness in North America. Pac. Seabird Group Bull. 5:83
Nol, E. and R.C. Humphrey. 1994. American oystercatcher. In A. Poole and F. Gill, eds. The Birds of North America. No. 82. 24 pp.