The Jackass Penguin
Essay by review • November 26, 2010 • Essay • 506 Words (3 Pages) • 1,385 Views
Habitat and Population
The Jackass penguin is the only penguin that breeds in South Africa. Its distribution among islands in South Africa is mostly affected by the cold, Benguela Current and also by offshore breeding sites.
Breeding occurs on Hollamsbird Island, off central Namibia and extends all the way to Bird Island in Algoa Bay. There are about 27 inhabited sites, which most are found on inshore islands. The best-known site is Robben Island. Among the three existing mainland sites the largest existing colony is on St Croix island near Port Elizabeth, with about 50 000 birds.
A typical foraging trip could range from 30 to 70 km for a single trip, while on the south trips average about 110kms per trip. But when penguins are feeding their young, the trip would be limited. A single dive of a penguin is estimated to last about two and a half minutes, and about 30m deep.
The present population of African Penguins has declined by 90 percent from that of 1900, when there was estimated to be 1.5 million birds on Dassen Island alone. This rapid decline is greatly due to commercial exploitations such as the exploitation of penguin eggs for food, pollution from oil tankers and guano (bird dropping) removal from their nesting grounds for use as fertilizer. As of the early 1990's there was an estimated 179 000 adult birds.
African Penguins breed colonially, mostly on offshore islands where there is less human disturbance. However with the use of guano for commercial purposes, hiding eggs under bushes and other objects has become more frequent.
African Penguins breed almost the whole year. Penguins are monogamous species, meaning they return to the same partner every year and even help each other take care of the young. Most of the time they also return to the same colony and the same nesting site each year.
Both parents take care of the chicks for the first fifteen days, after which they are taken care of one at a time by the adults. By this time, chicks already have gained full control over their body temperature and no longer need the heat from their parents. But, at this point the chicks are still very vulnerable to predators so the adults continue to look after the chicks for about thirty days old.
African penguin chicks have a moulting stage from 60 to 130 days of age. This moulting stage is the
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