Author: Tracy Borneman (TB), NC Cooperative Fish and Wildlife Research Unit, Dept. Biology, NC State University, Raleigh, NC.
Large, pied shorebird (40–44 cm long; 400–700 g), dark above on head and mantle, white on breast and flanks. Long, straight, bright red to orange bill. Long, pale pink legs, lacks hallux. Bright yellow iris, sometimes with dark flecks. Shows narrow, white wing stripe in flight. Long reddish bill laterally compressed. Yellow eyes with red eye ring and black head and neck, contrasting with brown mantle, distinguishes this from other species. Males and females visually indistinguishable. Juveniles have varying degrees of dusty orange to gray on bill and mottled brown feathers on back until fully mature. Otherwise similar to adult. (see Appearance)
Differs from adult European Oystercatcher (Haematopus ostralegus) in brown back, paler legs, shorter and narrower wing bars; lacks white “V” on upper rump, lacks white throat bar in immatures and nonbreeding adults. Magellanic Oystercatcher (H. leucopodus) has darker upperparts (mantle), red eye ring, dark-tipped secondaries, and darker under primary coverts. Populations in w. Mexico, Galápagos, and e. Argentina show indistinct lower border of black breast. The Patagonian population durnfordi hybridizes infrequently with the local H. ater where they are sympatric (Jehl et al. 1973, Miller and Baker 1980). On nw. coast of Baja California, the race frazeri interbreeds at least occasionally with American Black Oystercatcher (H. bachmani; Jehl 1985). Northern individuals of frazeri often show considerable black flecking on belly (Bancroft 1927, Jehl 1985, Edwards 1989). Jehl (1985) developed a numeric coding system for coloration of various oystercatcher plumage parts for classification of individuals on Baja California as H. bachmani, H. palliatus frazeri, or hybrids.