Hector’s dolphins inhabit the turbid coastal waters of New Zealand, where groups of 3 to 10 individuals gather at a time, swimming among the surf-lashed rocks close to shore. This beautiful, poorly known animal’s color pattern closely resembles that of the killer whale. Some individuals have been kept in captivity, where they were listless and seemed uncomfortable at first, but when their water was made slightly cloudy, conforming to their habitat in the wild, they responded favorably, settling down and becoming more responsive.
Physical Description: The body is fairly stocky with a barely discernible beak.
Color: The tip of the lower jaw and the sides of the head region are black, leading to and including the flippers. The dorsal region and the flanks are dark brown. The ventral area is white from the lower chin to the anus, sharply delineated from the dark dorsal regions. The white branches up on the lower peduncle area, sweeping sharply back toward the peduncle where it tapers to an end. The lower flanks are lighter than the surrounding regions from the flippers to the white ventral extensions — a distinction sometimes barely visible but defined by a longitudinal line across the flanks. The anal regions displays a color pattern that distinguishes males from females. Males have a single dark spot on the anus, while females have more than one. The dark flank regions extend under the body at the flippers to touch and extend back to an abruptly tapered end.
Fins and Flukes: The black dorsal fin is very rounded and tilted toward the rear. The very dark flippers are large and paddle shaped. The dark flukes are disproportionately elongated and pointed at their tips, with a definite median notch.
Length and Weight: Hector’s dolphins reach 5 to 6 ft (1.5 to 1.8 m) and 120 lb (54 kg).
Teeth: 30 to 32 small, conical are found in each side of the upper and lower jaws.
Feeding: Stomach contents from 2 specimens contained small quantities of shellfish, crustaceans, small fish, and squid.
Breathing and Diving: Little definitive information available.
Mating and Breeding: Calves are believed to be born during the December-January migration.
Herding: Usually seen in groups of 3 to 10; larger herds, up to several hundred, have been observed.
Distribution: Coastal waters of New Zealand. Also reported near Australia and believed to occur in Sarawak, Borneo. It does not avoid muddy or turbid waters, and will enter estuarine waters of the Clarence, Gray and Wanganui rivers of New Zealand.
Migration: Generally believed to migrate to the North Island, New Zealand, in December and January, and return to South Island in February.
Natural History Notes: This animal prefers to ride the wake rather than the bow-wave of passing ships. It is not known to expose much of its body as it swims and occasionally leaps from the water.