Hector's Dolphin

## Description

Hector's dolphin (Cephalorhynchus hectori ) is one of four dolphin species belonging to the genus Cephalorhynchus. Hector's dolphin is the only cetacean endemic to New Zealand, and comprises two subspecies: C. h. hectori, the more numerous subspecies, also referred to as South Island Hector's dolphin; and the critically endangered Māui dolphin (C. h. maui ), found off the West Coast of the North Island.

## Appearance

This animal is one of the most infrequent and smallest marine dolphins. Hector's dolphin is named after Sir James Hector, a New Zealand scientist, who was the first to seriously explore the species. Sexes generally look alike, though males are usually shorter than females. Unlike other dolphins, this animal lacks a beak. The short and stocky body reminds a torpedo by its shape, narrowing towards the tail. The belly is white or cream, whereas the back and the sides are light grey. The dolphins exhibit a gray band, running across the middle of the body. They also have a black patch, stretching from the back of the snout around the eye to the flipper.

## Distribution

Hector’s dolphin is a New Zealand species, typically found around the major part of the South Island. Maui’s dolphin, a sub-species of Hector’s dolphin, has a very limited range, restricted to off the west coast of the North Island. The animal occurs in shallow seashore waters within 7 km off the coast (generally, less than half a mile off the shoreline) at depths of up to 100 meters. At certain times of year, when prey items change their location, the dolphin can be seen right at the seashore.

## Behavior

Hector's dolphins usually gather into small groups, consisting of 2 - 10 animals, which occasionally unite into larger temporary groups, found in close proximity to each other. Individuals normally associate with each other for less than a few days. These diurnal animals generally live in the same area, sometimes, throughout their lives. Hector's dolphins are known to be active and playful animals: bow-riding and playing with seaweed are common activities in this species. Hector's dolphins typically spend their time swimming along the coastline, coming to the surface to breathe, diving to forage as well as playing. They can frequently be observed leaping out of the water and landing on their side with a loud splash. In addition, sometimes they flex their body at the surface and can swim on their sides while feeding. In order to show aggression, these dolphins usually splash water with their tail, chase, bite or make bubble-blows.

## Diet

Hector’s dolphins are carnivores (piscivores). They usually feeds in shallow waters with sandy bottom, consuming various species of fish such as flounder, red cod and mackerel, complementing its diet with crabs and squid.

## Reproduction

Hector's dolphins have polygynandrous (promiscuous) mating system, where both males and females mate with multiple mates. During the courtship, the animals practice close contact, leaping chasing as well as belly displays. The breeding season occurs during the austral summer. Usually, a female yields a single baby every 2 - 4 years with the gestation period, lasting 10 - 12 months. The calves are typically born in the late spring and summer. The offspring stay with their mother for the first 1 - 2 years of their lives. During this period, the female does not breed. Females and their young are known to separate from non-breeding conspecifics, gathering into calf-cow groups. By the age of 2 years, the young are independent, often joining groups, consisting exclusively of young dolphins. Males of this species are sexually mature at 6 - 9 years old, whereas females reach maturity by 7 - 9 years of age.

## Population

### Population threats

Hector's dolphin is often caught in commercial and recreational fishiers across the area of its habitat, being entangled in gillnets, which pose a serious threat to this animal's population. Living in coastal areas, the animal suffers from a number of factors, including pollution, vessel traffic as well as modification of its natural range.

### Population number

According to the IUCN Red List, the total population size of the Hector’s dolphin is about 7,000 mature individuals, including the North Island subspecies with population of 111 individuals. Overall, numbers of Hector’s dolphin population are decreasing today, and the species is currently classified as Endangered (EN) on the IUCN Red List.

### Ecological niche

Due to their diet, Hector's dolphins likely play an important role in controlling local fish populations.

## Fun Facts for Kids

Being related to other delphinid species, Hector's dolphins are slow swimmers, using the wave-like movement, or, otherwise, an undulating motion, while swimming. The small lungs of the animal are almost the size of human lungs, not allowing the dolphin to dive for more than 3 minutes at a time.

When swimming around boats, these animals often keep close to each other - a behavior that can be a sign of stress.

Hector's dolphins stand out of other dolphin species due to not using any whistles, but emitting only short and high-frequency clicks.

They are able to locate prey due to using echolocation, giving out a stream of high frequency sound, which bounces off an object, returning to the dolphin and carrying information about the sort, distance and speed of the object. In familiar areas, the echolocation ability of these dolphins does not function, and the animals often cannot sense threats.

Hector's dolphins are conscious sleepers: they never fall completely asleep in order to control the required amount of oxygen, because otherwise they would simply drown.

Dolphins are known as highly intelligent and playful animals. Moreover, along with chimpanzees, apes and elephants, they are one of the most intelligent animals in the world. In the case of good training, they are capable of completing difficult tasks as well as performing acrobatic tricks.