The emperor penguin, scientifically known as the Aptenodytes forsteri, is the largest of the 17 penguin species. These penguins are found exclusively on the ice packs of Antarctica. While there is very little to distinguish a male emperor penguin from the female, there are some subtle differences between the sexes, including their roles in courtship and breeding, their vocalisation and their proportion of the overall population.
Nest site selection
It is the male emperor penguin that selects the nesting site. Males will return to the rookery first, with females following within a few days. Males typically return to the rookery where they were born. Males prefer to find nesting sites on level ice that is both protected from the wind and close to feeding areas. Once selected, the male emperor penguin will defend his territory against other males.
The female emperor penguin selects her mating partner. Males perform a courtship act, known as an ecstatic display, to attract females; however, it is the females that battle it out to determine who will win the male. The ecstatic display by the male penguin includes trumpeting, head swinging and the puffing of feathers. Emperor penguins, like all penguins, are primarily monogamous. The generally only seek new mates if they are unable to locate their original mate.
While virtually identical in appearance, approximately 110 cm (44 inches) in height and 27 to 41 kg (60 to 90 lbs) in weight, the calls of the male and female emperor penguins are slightly different. Each penguin has a unique voice, recognisable to one another. However, these minute differences are undetectable to the human ear. While humans are unable to distinguish the unique voices, females do possess a higher-pitched vocalisation that can often be identified.
There is a distinct difference in the overall ratio of male and female emperor penguins. Of the approximately 400,000 emperor penguins in Antarctica, females comprise a much larger percentage of the colonies. This imbalance creates the natural competition that exists between females for mating partners.
The primary difference between male and female emperor penguins revolves around their roles in the breeding process. The female will lay a single egg, which she immediately turns over to male. The male will then incubate the egg for the next 64 days. The male will warm the egg by balancing it on his feet, while covering it with a feathered patch of skin, called a brood pouch. The male fasts during the entire courtship, mating and incubation period, losing as much as one-third of body weight. Just prior to the egg hatching, the female will return, allowing the male to feed. The two will then alternate caring for the penguin chick until it is old enough to be abandoned.