The name penguin is used for a group of flightless birds of the southern hemisphere whose appearance, upright and waddling walk hide their abilities as amazing swimmers and divers. There are 18 species of penguin, and all have their characteristics.
If you want to know more about penguins, please read on.
Habitat
Penguins breed in habitats ranging from the lava shores of equatorial islands to subtropical beaches, temperate forests, subantarctic grasslands, and antarctic sea ice.
They are, however, basically adapted to cool conditions and, in tropical areas only occur where cold-water currents.
Most species occur between 45 and 60 degrees south, with the highest species diversity in the New Zealand area and the Falkland Islands.
However, the greatest numbers live around the coasts of Antarctica and on the subantarctic islands. Winter distributions and movements are little known. Tropical and warm temperate species do not migrate.
Description
Although penguins show a wide range in weight and size, they are remarkably similar in structure and plumage, being bluish-gray or bluish-black above and white below.
Species with distinguishing marks such as crests, crowns, faces, and neck bands are chiefly on the head and upper breast, being visible while the birds are swimming on the surface.
Chick plumages are gray or brown or have one of these colors along the back and white on the sides and undersurface. Juvenile plumage is very similar to adults. Males are generally slightly larger than females.
Penguins are densely covered by three layers of feathers. They are highly streamlined, with their wings reduced to strong, narrow, stiff flippers. This allows them to swim rapidly, although flight is not possible.
The feet and tarsus are short, and the legs are set well back and are used as rudders, along with the tail. On land, penguins rest on their heels with stout tail feathers forming a prop.
The short legs make them waddle, but on ice, they can be seen moving quickly on their bellies. They have solid bones and generally weigh only a little less than water, helping to reduce the energy required to dive.
Bills are generally short and stout with a powerful grip. Emperor and King penguins have long, slightly downcurved bills adapted for capturing fast-swimming fish and squid at depth.
As well as having to swim efficiently, penguins also need to keep warm in cool, near-freezing waters. Penguins have a very waterproof feather coat and a well-defined fat layer to keep them warm.
They also have a heat-exchange system of blood vessels in the flippers and legs, ensuring that venous blood returning from their extremities is warmed up by the outgoing arterial blood. This effectively reduces heat loss from the body.
Tropical penguins tend to overheat easily, so they have larger flippers and areas of bare facial skin to lose excess heat. They also stay out of sunlight by living in burrows.
Diet
Penguins’ main prey are crustaceans, fish, and squid, which they chase, catch and swallow underwater. It has been suggested that they may be assisted in finding prey using a form of echolocation based on sounds produced by their swimming movement.
Fish are important in the diet of inshore feeders, such as the African, Little Blue, and Gentoo penguins, although King and Emperor penguins will also feed on fish.
Squid is the preferred meal of the King penguin and is frequently eaten by Emperor and Rockhopper penguins.
Large amounts of krill are the principal prey of Adelie, Chinstrap, Gentoo, and Macaroni penguins, while other crustaceans are important to Rockhopper and Yellow-eyed penguins.
Krill do not appear on the surface during the day, which is when penguins rearing chicks on this food are mainly at sea. However, they may still feed at night, traveling to and from their colony during the day, or dive to find prey during the day.
The Little Blue penguin is unusual in its feeding habits. They are the smallest species and feed their chicks after nightfall. They cant dive as well as other penguins and need to feed around dusk when their prey is at the top of the ocean.
By feeding at dusk, the Little Blue penguin also manages to avoid predators as it comes ashore at night.
Both parents usually bring food to the chick each day for those species that feed inshore. Adelie, Chinstrap, and crested penguin parents are usually away at sea for more than a day, so the chick only receives one meal per day.
King and Emperor penguin chicks are fed large meals at infrequent intervals, normally every three or four days.
Only in large species do meals exceed 1kg (2.21b), but even smaller species chicks can eat 500g (about 11b) of food.
Reproduction
Emperor penguins lay their eggs in the fall. King penguin chicks overwinter at the breeding colony but are rarely fed during this period and grow mainly during the summer.
Most species that live in cold temperate, including the Antarctic and most subantarctic penguins, breed in spring and summer. Breeding is synchronized within and between colonies.
Gentoo penguins and the more northerly crested penguins have longer breeding seasons and at different times each year. In Jackass and Galapagos penguins, there are usually two main peaks during the year, but laying occurs throughout the year.
Little blue penguins and those in South Australia are similar, as some pairs can raise two broods successfully.
In most species, males come ashore first to establish territories where they are soon joined by their old partners or by new birds that they attract to the nest site.
Penguins normally mate with the partners of previous years, with some Yellow-eyed penguin couples lasting as long as 13 years. Little Blue penguins have mated with the same partner for 11 years, while Adelie penguins have not been seen to last between 6 years.
The age of breeding differs according to the species. Macaroni penguins breed first when at least five years old, while Emperor, King, Chinstrap, and Adelie penguins are at least three years old in females, or four in males.
Little blue, Yellow-eyed, Gentoo, and Jackass penguins breed when at least two years old. In Adelie penguins, most birds visit the breeding ground as three or four-year-olds.
Up to about seven years of age, Adelie penguins arrive earlier each season, making more visits and staying longer. Some females first breed at three years of age, while males are four, but most females and males wait another year or two, and some males do not breed until eight.
Emperor and King penguins lay a single egg, while the rest normally lay two. The Yellow-eyed penguin’s age affects fertility, with hatching most successful when they are between 6 and 8. In crested penguins, the first clutch is much smaller than the second
The Fiordland penguin lays both eggs and normally hatches, but only one chick is ever reared. This is an adaptation guaranteeing the survival of its sibling when food is scarce.
This system may be designed to cope with high egg loss because of the fighting in the closely packed colonies.
Alternatively, when both eggs hatch, the difference in the size of the chicks may ensure that only one survives for long. In other penguins, hatching is also staggered, reducing brood numbers by favoring the first hatched chick.
All penguins have the capacity for storing fat reserves, but only the Emperor, King, Adelie, Chinstrap, and crested penguins use long fasts during the courtship, incubation, and brooding periods. Fasts can last as between 110-115 days for male Emperor penguins and 35 days for Adelie and crested penguins. This can result in losing up to 45 percent of their body weight.
Gentoo, Yellow-eyed, Little Blue, and Jackass penguins usually change incubation every 1 or 2 days. Chicks grow very quickly. After 2 to 3 weeks or 6 weeks in Emperor and King penguins, the Adelie, Gentoo, Emperor, and King penguin chicks in open areas form large creches.
Chinstrap, Jackass, and crested penguins have smaller aggregations with chicks from adjacent nests. Once the molt is complete, chicks usually start swimming. In crested penguins, almost all chicks leave within one week, and there is no further care from the parents.
In Gentoo penguins, chicks return to shore sometimes and obtain food from their parents for at least two or three weeks. It does not appear that chicks are fed by their parents in the sea.
In most species, once chicks are independent, the parents put on weight for a molting and fasting period of 2 to 6 weeks, during which fat reserves are used twice as fast as in incubation. In Jackass and Galapagos penguins, the molt period is less defined, occurring at any time between breeding attempts.
Immature birds usually complete molt before breeding starts, and in crested penguins, the timing of this molt becomes later with age until the first breeding attempt.
Survival
The survival of adult penguins from one year to the next is relatively low, being 70 to 80 percent for Adelie penguins, and about 85 percent for most other penguins, except Emperor penguins with an impressive 95 percent.
Penguins are thus not particularly long-lived, with records of 19-year-old Yellow-eyed and Adelie penguins being exceptional. However, the average lifespan is only about 10 years, except for Emperor penguins, which can live up to 20 years.
Juvenile survival is relatively high in most Antarctic species, except Emperor penguins, where only some 20 percent of fledglings survive their first year.
Sociable
Most penguins are highly social, both on land and at sea, and often breed in vast colonies, only defending the small areas around their nests. Courtship and mate recognition behavior are most complex in the colonial Adelie, Chinstrap, Gentoo, and crested penguins, although not so much in the Yellow-eyed penguin.
Despite living in burrows, Jackass penguins usually breed in dense colonies and have elaborate visual and vocal displays. Little blue penguins, whose burrows are more dispersed, are largely nest oriented.
Emperor penguins, however, have no nest site and show only behavior oriented to their partners. The great variation in the sequence and patterning of their trumpeting calls provides all the information needed for individuals to recognize each other.
In King penguins, the incoming bird goes close to its nest site, calls, and listens for a response. King and Emperor penguins are the only penguins where the two sexes can easily be distinguished by their calls.
Predators
Although flightless, adult penguins have few natural predators on land because they choose isolated breeding sites, and their beaks and flippers are effective weapons.
Eggs and chicks are taken by skuas and various other predatory birds. At sea, Killer whales, Leopard seals, and other seals and sharks catch penguins.
The populations of several species of Antarctic penguins have increased in recent decades due in part to the reduction of baleen whales, which ate most of the krill.
Some King penguin populations have also increased, perhaps partly a recovery from when they were killed so oil could be extracted from their blubber. In the past, many penguin populations were reduced by egg collecting. However, this is something we don’t need to worry about too much today.
Endangered Penguins
Five species of penguin are presently endangered. Galapagos penguins, with a total population of about 3,000-8,000 penguins, with about 800 breeding pairs left, breeding only on the Galapagos and Isabela Islands.
On Isabela Island, they are preyed upon by feral dogs and cats, but starvation and overheating can also cause death.
Yellow-eyed penguins have declined to between 6,000 to 7,000 individuals and only 1,700 breeding pairs.
Changing patterns of land use and other human disturbance in the coastal dune systems off New Zealand, where they breed, have led to their decline. Populations on islands where protection is more feasible have suffered less.
The African penguin occurs in areas with large amounts of nutrients that support fishing industries. The fishing industries off the west coasts of South Africa depend on the same food as penguins in the area.
Sanccob, advises that there are about 14,700 pairs, with 10,400 pairs in South Africa and 4,300 pairs in Namibia. Populations of these species have decreased alarmingly because of competition for food.
The Northern Rockhopper penguin is another endangered penguin. There are approximately 413,700 individuals left in the wild.
The Erect-crested penguin lives in Antipodes and Bounty Islands of New Zealand. There are approximately 150,000 individuals alive today, but they are under threat from habitat destruction.
All penguins are highly vulnerable to oil pollution. This seriously threatens the African penguin, as many colonies lie near the tanker routes around the Cape of Good Hope.