How do penguins reproduce?
Perpetuating the species is a paramount issue for any animal, and penguins are no exception. Although they cannot fly, they are still birds that reproduce laying eggs, only that the incubation time, the number of eggs and the care devoted to them are different from the habits of the flying birds.
A penguin that has reached sexual maturity is ready to start breeding. In this sense, the size of the body influences the time it takes for an individual to reach maturity or begin to mate. For example, the Emperor penguin (Aptenodytes forsteri) reaches maturity around 5 or 6 years old, but the little blue penguin does at 2 or 3 years of age. Yes, it seems that the smaller the body is, the less time it takes to mature sexually and reproduce. On average, penguins begin to mate by their fifth year of life, but some males can wait until their eighth year.
Penguins mating.
Goal: finding a partner.
For birds that live in colonies, finding a partner is not that challenging, and this is what happens with penguins because they are in constant contact with each other; this does not mean that they mate indiscriminately or at any time since they also have particular preferences and requirements. Thus, for most species, there is a season in which they lay eggs and take care of their chicks, and usually, this happens in spring and summer, although some species living in temperate regions may nest during any season of the year.
But, it is worth clarifying something: penguins tend to be monogamous, that is to say, they keep a single partner during a whole season or all their life. The clearest example of the latter are the couples of Emperor penguins (Aptenodytes forsteri), who spend their entire lives together and come to know themselves so well, that they recognize each other by vocalizations. According to some observations, some females take the decision of having 1-3 sexual partners during a season; Similarly, some males mate with 2 or 3 in the same breeding season, but they are the exception.
If a young, sexually mature penguin is in the mating season, he proceeds to find a suitable partner and he is the first to establish the nest site. The males of all species, usually more robust and 1 to 29 percent larger, have the task of beginning courtship and attracting a female. To do this, they emit loud vocalizations, and other mature males start to do the same. It’s a whole symphony of penguins! Obviously, the sounds are different from each other as people’s voices, but the larger males differ from each other by having voices that sound, somehow, deeper.
The courtship period typically lasts 2 to 3 weeks, and attention-grabbing activities vary significantly among species. In general, there are three recognized behaviors:
A) Euphoric.
The male moves the head energetically while vocalizing and thus warning other males to stay away from their place.
B) Mutual euphoria.
Both male and female perform movements at the same time to draw attention to one another.
C) Reverential.
Characterized by the inclination of the head and the placement of the beaks together, in an attempt to reduce the tension between them and reduce the chances of aggression.
King penguins, adult and chick.
In most cases, the nest is already available before mating. Penguins are philopatric, which means that they always return to the colony in the same place where they previously nested. Species such as the chinstrap penguin (Pygoscelis antarcticus) and the Adelie penguin (Pygoscelis adeliae) construct their nest with stones, while the emperor penguins and the king penguins keep their eggs in a brood pouch or special bag located at the top of their paws. Also, they are the only species that lay only one egg while all others usually lay two.
The incubation period varies by species. The Erect-crested Penguin (Eudyptes sclateri) incubation takes about one month, but for the emperor penguin, it takes between 62 and 66 days before hatching. Males and females take turns incubating in the nest, often built with small rocks and vegetation. Some species prefer to nest in excavated holes and some other build nests in natural caves or crevices.
The case of the emperor penguin is unique. After the female lays the single egg, she carefully transfers it to the male for incubation. If the egg drops or touches the cold floor during the transfer, it immediately freezes and dies. After delivering the egg, she travels to the sea for food. Meanwhile, the male fast during more than two months of the incubation period, until the mother returns from the sea and the chick breaks the shell, then the father goes to the ocean for feeding. The male survives all this time, thanks to its fat reserves, but it loses up to 45 percent of its body weight.
Goal: take care of the little ones
Chicks take up to 3 days to leave the shell. They come into the world almost without feathers, blind and defenseless, but the parents feed them and take good care of them. After a few weeks, soft brown feathers cover the body of the young.
During this time, the food consists of regurgitated stuff that the parents give to the chick directly from their mouth. To keep it warm, they place it in the brood pouch used to incubate the egg. In certain species, all chicks in the colony gather in a nursery, where they have greater protection against predators. However, adults only feed and care for their chick.
Sources:
https://seaworld.org/en/animal-info/animal-infobooks/penguin/reproduction
https://seaworld.org/en/animal-info/animal-infobooks/penguin/hatching-and-care-of-young
http://animaldiversity.org/search/?q=penguins&feature=INFORMATION
Animals, a visual encyclopedia. Second edition. Smithsonian 2012.
World of Animals Magazine. Issue 04. Imagine publishing.
http://www.antarctica.gov.au/about-antarctica/wildlife/animals/penguins/emperor-penguins/breeding-cycle
BioExpedition Publishing © 2017.
