Appearance

Despite the widespread abundance and distribution of this species, no qualitative or quantitative studies of the sequence, timing and extent of molt has been done. Because this species is closely related to the European Oystercatcher and was/is thought to be conspecific with it by most authorities (Peters 1934, Murphy 1936, Hellmayr and Conover 1948, Heppleston 1973, Sibley and Monroe 1990, but not by Ridgway 1919, or the Am. Ornithol. Union 1886 – 1983), it is likely that the sequence and extent of molts are similar to this species (Dare and Mercer 1974, Pienkowski and Knight 1975, Boere 1976, Hulscher 1977, Wilson and Morrison 1981, Koopman 1992). However, the timing and location (breeding ground, migratory staging area, or wintering ground) of molt are more likely to differ between these species.

Names of colors that are capitalized refer to those in Smithe (1975) unless stated otherwise.

Hatchlings

H. p. palliatus and H. p. pitaney: Dark grayish chin, throat and breast clearly demarcated (as in adults) from remainder of underside which is entirely white. Dark breast sometimes extends dorsally to form a collar around nape that is darker than adjacent head and back plumage. A narrow black stripe runs from the base of the bill through each eye to the nape. Two parallel black stripes down back, and a black dot behind eye. A black stripe on each side of body from base of tail (top of femur) to wing (shoulder) separates darker dorsal down from light ventral down. Otherwise upperparts Drab (color 27) with rump and flanks tipped with Buff (color 124) to Warm Buff (color 118). Auriculars and areas above and below eyes light buffy drab (Avellaneous of Ridgway 1912); sides and back of neck uniformly Light Drab (color 119c; Bent 1929, Murphy 1936, Webster 1943; photos in Bancroft 1927, Tomkins 1954, Hall 1960; line drawing and photo in Jehl 1968; color plate in Harrison 1978).

H. p. frazari: Same as palliatus except rump and flanks slightly lighter and face, wings, and lower back slightly grayer; sides and back of neck darker (Dark Drab [color 119B] to Van Dyke Brown [color 221]); 3 or 4 small black spots on crown (less extensive and numerous than in European Oystercatcher). Chicks occasionally have several black spots on back of head and light shade of Drab Gray (color 119D), instead of white, underparts except for a triangular white patch on upper breast (as in Black Oystercatcher; Webster 1943). However, Palmer (1967) states that chicks in Baja California (which must belong to the subspecies frazari [Am. Ornithol. Union 1957]) are “nearly all dark,” paralleling darker plumage of parents (see below).

H. p. galapagensis: Darkest of all subspecies. Throat Van Dyke Brown (color 219); back Drab (color 27), Rump black (Webster 1943).

H. p. durnfordI: unknown.

Juvenal Plumage

Prejuvenal molt complete. We assume that development of this plumage is similar to that of the Black Oystercatcher of w. North America which was described by Webster (1942) as follows: By 12 d, Juvenal plumage develops on flanks and along ventral midline; primaries pierce skin. Between 14 and 21 d, Juvenal secondaries, secondary coverts, rectrices, auriculars, and crown feathers appear. Down remains attached to tips of Juvenal feathers, especially on rump, underside of neck, flanks, and legs. Juvenal plumage is fully developed by 6 wk, and last traces of down (usually on inner thighs) disappear shortly thereafter.

Following Bent (1929) and Murphy (1936), in Juvenal plumage, the back, scapulars and wing coverts are light Raw Umber (color 223) tipped with Clay to Cinnamon color (colors 123b and 123a, respectively); crown, sides of head, and chest are Raw Umber (color 223) tipped with Cinnamon (color 123A); chin and throat are mottled Fuscous (color 21) to “buffy;” whitish feathers around base of bill; upper tail coverts are white tipped with “buffy;” rest of underparts are white. Tail is Raw Umber (color 223) tipped with Cinnamon (color 123A); wing is Raw Umber (color 223) with white wing bar consisting of greater upper secondary coverts, widest in the middle and tapering both distally and proximally. By end of Jul, lighter colored feather tips have nearly disappeared due to wear. In general, birds exhibit progressively less white and more black in the wings, rump, tail coverts, and belly from north to south (Murphy 1925, 1936: 974; Palmer 1967). The same applies among species of oystercatchers worldwide (Murphy 1925, 1936).

Basic I Plumage

Begins in early Sep; ending date of molt unknown. Incomplete. All body plumage except some Juvenal scapulars and wing coverts, and some inner secondaries replaced. No other remiges or rectrices are known to be replaced (Forbush 1925, Bent 1929), but this may occur as it is known in other Haematopus species (Hulscher 1977). Head and neck Fuscous (color 21) or Sepia (color 119); mantle Dark Neutral Gray (color 83); underparts white. First Basic plumage identical to Definitive Basic plumage except for retained Juvenal scapulars, wing coverts and rectrices that are lighter and duller in color (Bent 1929).

Alternate I Plumage

Exact timing unknown. Probably Jan to Mar. Partial, including most but not all body plumage. Identical to Definitive Alternate plumage except some Juvenal body plumage typically retained until next molt (Definitive Prebasic).

Definitive Basic Plumage

Definitive Prebasic molt complete. Exact timing unknown. Probably begins a month or more earlier (Apr or May) in second-year birds which do not breed as well as older nonbreeders or failed breeders compared to successful breeders. Among successful breeders, females probably begin molt later than males (Webster 1942, Dare and Mercer 1974, Wilson and Morrison 1981). Probably finishes between Jul and Sep.

Following Murphy (1936), in palliatus, head, neck, and upper chest uniform black with faint bluish green gloss; white streak immediately below lower eyelid; back, scapulars, rump, anterior median upper tail coverts plain grayish brown or brownish gray (similar to Smithe’s [1975] colors 119A and 119B); median anterior tail coverts sometimes edged white; lateral and posterior upper tail coverts white, the latter rarely with a few dusky spots or blotches. Lower chest, belly, under tail coverts, axillars, and under wing coverts white. The under wing coverts sometimes tipped with brownish gray, and the carpometacarpal region (wrist) spotted dusky. P1–P4 (less frequently P1–P5, P1–P6 or P1–P7) have basal white areas, usually 25 mm or more in length, on their shafts and outer webs. Tips of median secondary coverts, all exposed portions of greater secondary coverts, and secondaries immediately distal to tertials are immaculate white. More distal secondaries are white on their inner webs and basal part and distal edges of outer webs, but otherwise are deep brownish gray. Primaries and their coverts dull black. Tail deep brownish gray becoming darker (sometimes nearly black) distally. Basal half or more of outer rectrices white.

H. p. pitanay: Basal white areas of primaries reduced or lacking, wing bar on secondaries more uniform in width; wing more narrow (Murphy 1936, Hayman et al. 1986).

H. p. frazari: Demarcation between dark breast shield and white belly irregular; intermediate plumages between frazeri and H. bachmani occur due to hybridization (Jehl 1985). Wings broad; dark flecking on upper tail coverts; no white on markings on primaries.

H. p. galapagensis: Demarcation between dark breast shield and white belly irregular as in frazari . Darkest of all subspecies. Darker black dorsally; heavier blackish mottling on breast along border between dark breast plate and white belly (Murphy 1936).

H. p. durnfordi: Wings narrow. Less white on outer greater secondary coverts (Hayman et al. 1986). Has white markings on primaries like palliatus, but has dark breast pattern like galapagensis . Murphy (1925: 7) showed that many of the characters ascribed to the type of durnfordi, and to other specimens designated to this subspecies, are untenable, thus bringing into question the validity of this subspecies.

Definitive Alternate Plumage

Definitive Prealternate molt timing unknown. Probably Jan-Mar. Extent probably the same as First Prealternate molt. Plumage color same as Definitive Basic but dark body plumage glossier.

Bill

Fledgling bill mixture of grays and buffs, becoming pale orange with dusky at extreme tip by 12 mo (Cadman 1980). Adult bill vermilion with yellowish tip and scarlet red base.

Iris

Brown in fledglings, becoming pale lemon yellow by 12 mo and lemon yellow in adults (Prater and Marchant 1977). Although eye color is described as being lemon yellow in both mid- to late second-year (Cadman 1980) and older birds (Prater and Marchant 1977), eye color darkens with age through third-year in European Oystercatcher (Prater and Marchant 1977, Cramp 1983). Thus, with experience, eye color may be a useful character for aging birds in their second and third years.

Eyelids

Chrome orange (Murphy 1936, Palmer 1976, Blake 1977).

Legs

Dull grayish in fledglings, becoming gray by 12 mo and pinkish white in adults