Aggressive Behavior of Short-Finned Pilot Whales Towards Sperm Whales in the Gulf of California: Insight into Food Competition

Short-finned pilot whales (Globicephala macrorhynchus) inhabit tropical, subtropical, and warm temperate waters of the world, generally offshore, where they feed mainly on squid (Jefferson et al., 2008; Olson, 2009). Along with five other delphinids, the pygmy killer whale (Feresa attenuata), the melon-headed whale (Peponocephala electra), the false killer whale (Pseudorca crassidens), the killer whale (Orcinus orca), and the long-finned pilot whale (Globicephala melas), they form a group colloquially called “blackfish,” which preys on other cetaceans, either commonly or occasionally (Carwardine, 2002; Weller, 2009). Sperm whales (Physeter macrocephalus), the largest odontocete, are characterized as deep, long divers and teutophagous in offshore waters (Whitehead, 2003). Herein, we describe an observation of short-finned pilot whale aggressive behavior towards sperm whales during a cetacean survey in the southern Gulf of California.