In past, sometimes considered conspecific with H. ostralegus; has been thought conspecific with H. ater. Name H. frazari probably invalid, referring to a hybrid swarm formed between present species and H. ater bachmani in Gulf of California and W Mexico; hybridization in this overlap zone limited, and some authorities retain frazari as race of present species. Present species known to hybridize also with H. a. ater in S South America. Some differences in adult morphology and plumage between nominate palliatus and race galapagensis, coupled with differences in chick coloration, suggest that galapagensis may warrant separate species status; reference in HBW to this form’s “markedly hypertrophied feet”, however, not borne out by examination of museum specimens. Several proposed races probably insufficiently distinct to warrant recognition: pitanay of W South America (from Ecuador to SC Chile); durnfordi of E South America (S Brazil to SC Argentina); and prattii of Bahamas. Two subspecies currently recognized.
Food and feeding
Status and conservation
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