The eastern rockhopper penguin (Eudyptes chrysocome filholi) is a crested penguin with yellow crest feathers. It is a subspecies of the southern rockhopper penguin (Eudyptes chrysocome) found in subantarctic regions and the Indian Ocean. It is one of the smallest crested penguins and has distinctive pink margins around its bill.
Description
The eastern rockhopper penguin is a small, crested penguin with a black back and throat, a white belly and pink feet. This seabird measures approximately 45–55 cm in length, and weighs 2.2–4.3 kg. It has a thin yellow stripe that stretches from its lower forehead, over its red eye and splits into crest feathers at the back of its head. The crest feathers are composed of long, thin, spiky yellow feathers on either side of the penguin's head and they are joined by shorter black feathers. Rockhopper penguins have an orange-brown bill and the eastern rockhopper penguin has distinctive pink margins around the bill. Males and females differ in body size and size of their bill; males are generally larger and have a thicker bill.
Fledglings, which are around 65 days old, are bluish black all over and lack crest feathers. They also have a smaller, thinner bill than juveniles and adults. Juveniles, which are penguins aged 1 to 2 years old, are a black-brown color with a grey throat. They develop a brown-orange bill that is darker than the adult coloring and have small yellow crest feathers. Eastern rockhopper penguins molt and get their adult plumage at 2 years old.
Taxonomy
The rockhopper penguin can be divided into two species; the northern rockhopper penguin (Eudyptes moseleyiI) and the southern rockhopper penguin. These populations differ in many ways including morphological, ecological and behavioural differences. The northern rockhopper penguin is larger than its southern counterpart and has longer crest feathers. Other morphological differences include different color patterns on the underside of their flipper and different size eyestripes. They also exhibit different behavioural traits such as foraging in different water temperatures. Two subspecies of the southern rockhopper penguin are recognized; the eastern and the western rockhopper penguin (Eudyptes chrysocome chrysocome). These subspecies differ mainly in their distribution; the western species is found in Cape Horn, South America and the Falkland Islands while its eastern counterpart occupies the Southern Indian and Pacific Ocean. The eastern rockhopper penguin can also be distinguished by its pink margins around the bill.
Habitat and Distribution
The eastern rockhopper penguin is found in the southern Indian and Pacific ocean from Prince Edward Islands to the Antipodes Islands. Rockhopper penguins, in general, occupied a circumpolar distribution in the arctic during breeding season. Eastern rockhopper penguins breed in the Marion Islands, Macquarie island and subantarctic islands in New Zealand such as the Antipodes islands and Campbell island. These penguins occupy a mainly marine pelagic habitat and only return to land to breed and moult. They spend the winter months, approximately April to October, in the southern Indian Ocean foraging for food and can spend up to 6 months at sea. They travel, on average, 2000 to 4000 km away from their breeding site during this winter period. This species mainly forages in cool waters; ocean temperatures of less than 4.5 degrees Celsius.
Eastern rockhopper penguins are surface nesters and will build their nest on slopes or rocky shores near the coastline. Colonies will usually form on steep cliffs near the sea and can contain tens-of-thousands of nests. Their nests are made of small pebbles and can occasionally contain some vegetation. Some colonies have settled within grasslands such as tussock, however the soil often erodes down to rock with the accumulation of guano and trampling over a few decades. Eastern rockhopper penguins are rarely found more than 200 meters away from the coastline, since it is ideal to remain near their food supply.
Behavior
Vocalization
Eastern rockhopper penguins use calls for parent-chick recognition when returning to the colony with food. They also use a song for courtship that can be described as a short repeated rhythmic ascending song. The song of an adult rockhopper penguin can have 5-30 syllables with the first syllable the longest. Their contact call used by chicks and adults is a very short shrill bark.