Pilot Whales: Globicephala melas and G. macrorhynchus

Abstract

Most pilot whales appear black or dark gray in color. The body is robust with a thick tailstock. A wide, broad-based falcate dorsal fin is set well forward on the body. The flippers are long, slender, and sickle shaped. A faint gray “saddle” patch may be visible behind the dorsal fin as well as a faint postorbital blaze. Calves are paler than adults. Pilot whales exhibit striking sexual dimorphism in size, similar to that observed in sperm whales and killer whales. Adult males are longer than females, develop a more pronounced melon, and have a much larger dorsal fin. The function of sexual dimorphism in pilot whales is unknown, although several have been hypothesized. The males' enlarged features may be used for display to other males or females or for increased agility when maneuvering for mate access or for herding females. Long-finned and short-finned pilot whales are difficult to distinguish at sea. The morphological differences between the two species are subtle: length of flippers, differences in skull shape, and number of teeth. Pilot whales are generally nomadic, but resident populations have been documented in a few locations such as coastal California and Hawaii. Common habitats are the continental shelf break, slope waters, and areas of high topographic relief. Seasonal inshore/offshore movements of pilot whales are related to the distribution of squid, their favorite prey. Pilot whales are highly social and are usually found in schools, or pods, averaging 20–90 individuals. Pilot whales are polygynous. Pilot whales share several features of life history with other large odontocetes: long life span, delayed maturity, different rates of maturation for males and females, seasonal mating, and the production of a single calf in multiyear intervals.