Breeding seasons differ from species to species. Most species have an annual breeding season – spring through to summer.
The king penguin has the longest breeding cycle of all the penguin species, lasting 14 to 16 months.
A female king penguin may produce a chick twice in every three breeding seasons.
Emperor penguins breed annually during the antarctic winter, June through to August. The Little penguin breeds throughout the year and has the shortest breeding cycle, about 50 days. Some of the temperate penguins, like the Humboldt penguin and the African penguin, tend to nest throughout the year.
Courtship varies among the species. It generally begins with both visual and auditory displays. In many species, males display first to establish a nest site and then to attract a mate.
Penguins head for special nesting areas on the shore. The area where penguins mate, nest and raise their chicks is called a ‘rookery’. Males arrive first to the rookeries to establish and defend their nesting sites. When penguins are ready to mate, the male stands with his back arched and wings stretched. He makes a loud call and struts about to attract a female. When the penguins find a mate, they bond with each other by touching necks and slapping each other on the back with their flippers. They also ‘sing’ to each other so they learn to recognize each others voices. Once a penguin finds a mate, they usually stay together for years or for as long as they have chicks.
Eggs and Incubation
Eggs may be white to bluish or greenish. The shape varies among species. In Humboldt penguins and Adelie penguins the egg is more or less round. In Emperor penguins and King penguins the egg is rather pear-shaped, with one end tapering almost to a point. Penguins stand upright while incubating a single egg on the tops of their feet under a loose fold of abdominal skin. Under this loose fold is a featherless patch of skin called a brood patch, which occurs in all incubating birds. The brood patch contains numerous blood vessels, that, when engorged with blood, transfer body heat to the eggs.
A nest of eggs is called a ‘clutch’, and with the exception of Emperor penguin and King penguin, clutches usually contain two eggs. A clutch with more than one egg presents a better chance of at least one chick surviving. Incubation is the time spent warming the egg before it hatches. Once the female has laid her egg, the male will be left to watch the nest while the female will go away to feed. She can take up to two weeks to return. When she returns, she will incubate the eggs while the male goes off to feed.
Hatching of Penguin Eggs
Chicks first occur by poking a small hole in the egg. They then chip at the shell until they can push off the top. Chicks may take up to three days to chip their way out. Once the egg hatches, the chick will immediately start ‘calling’ so that its parents will recognise its voice.
A fine down covers most newly hatched chicks. Down feathers of different species may be white, grey, black, or brown. Down feathers are not waterproof and chicks must remain out of the water until they acquire their juvenile plumage. Adult plumage is acquired at about one year. In all species, the colouration and markings of chicks separate them from adults. Once the chick is strong enough, the parents will head off into the ocean to find food. All the chicks are left together on the shore in a ‘nursery’. When all the parents return, they will instantly recognise their own chicks voice having learned it from birth.
Caring For Penguin Chicks
Chicks require attentive parents for survival. Both parents feed the chick regurgitated food. Adults recognize and feed only their own chicks.
Male Emperor penguins exhibit a feature unique among penguins. If the chick hatches before the female returns, the male, despite his fasting, is able to produce and secrete a curd like substance from his oesophagus to feed the chick allowing for survival and growth for up to two weeks. Parents brood chicks (keep them warm) by covering them with their brood patch.
A chick depends on its parents for survival between hatching and the growth of its waterproof feathers. This period may range from seven weeks for Adelie penguin chicks, to 13 months for King penguin chicks. Once a chick has fledged (replaced its juvenile down with waterproof feathers), it is able to enter the water and becomes independent of its parents.