Attack of the Killer Dolphins
“Ah, dolphins. So sweet, so playful, so… vicious?
Yes, bottlenose dolphins have been known to kill harbor porpoises when the two species’ paths cross. Off the coast of California, warmer waters triggered by El Nino have allowed the dolphins to creep farther north into the porpoises’ territory. From 2007-2009, researchers saw 23 bottlenose dolphins attacking porpoises in Monterey Bay. And examinations of 216 porpoises stranded in California from 1998-2010 revealed that about a quarter of the animals had likely been killed by dolphins. Cause of death: blunt force trauma.
Why such aggression? The species probably aren’t battling over food, researchers say in Marine Mammal Science. Harbor porpoises eat market squid, anchovies, rockfish, and sardines, while bottlenose dolphins prefer surfperches and croakers. Instead, male dolphins — which sometimes kill young dolphins — may be “practicing” their infanticidal behavior on the porpoises or simply mistaking porpoises for dolphin calves.”
Learn more at Conservation Magazine.