Lord Howe Island.
Genetic data suggest that both species formerly placed in Procelsterna should be included in genus Anous#R. Temperate and subtropical counterpart of tropical A. ceruleus, to which it is closely related; sometimes considered conspecific, but has white vs grey head, hindneck, underwing and underparts (3); paler grey upperparts (1); longer bill, toes and notably wings (effect size 4.02, score 2). Although this score reaches only 6, the near-”parapatric” arrangement of populations across the Pacific Ocean roughly at the Tropic of Capricorn, in combination with the different size, is highly suggestive of a distinct ecology (putative score 1), and species status is considered appropriate. Some authors have claimed that races of SE Pacific belong to A. ceruleus, but specimen evidence refutes this. Three subspecies recognized.
Food and feeding
Status and conservation
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