False Killer Whales (Pseudorca crassidens) around the main Hawaiian Islands: long-term site sidelity, inter-island movements, and association

The false killer whale is one of the larger members of the fam-ily Delphinidae, with adult males reaching lengths of almost 6 m and females reaching up to 5 m. The common name comes from similarity not in external appearance to the killer whale ( Orcinus orca) but rather in skull morphology of these two species. In fact, the two species do not appear to be closely related; based on genetic simi-larity, false killer whales appear to be most closely related to the Risso’s dolphin ( Grampus griseus), melon-headed whale ( Peponocephala electra), pygmy killer whale ( Feresa attenuata), and pilot whales (Globicephala spp.). There is evidence of geographic variation in skull morphology ( Kitchener et al., 1990), but no subspecies are currently recognized. Largely black or dark gray in color (usually with a lighter blaze on the ventral surface between the fl ippers), it is easily recogni-zable with its rounded head, gracile shape ( Fig. 1) , small falcate dorsal fi n located at the midpoint of the back, and distinctive fl ip-pers (with a bulge on the leading edge). Scars from inter- and intra