Reproduction

Nesting takes place at a large ice-free area of rock. Here up to 280,000 pairs of Adelie penguins will make their nest. Typically they will use the same nest and have the same partner each year.

The nest is formed from rocks and built on a slope. This means that as snow melts around it the water will run away from the nest. These birds are described as aggressive and often steal rocks from their neighbors.

Males work to impress a female by building the largest nest they can.

A pair will deposit an average of 2 eggs in to their nest which are incubated for between 35 and 40 days. The eggs are laid two days apart. When one parent returns from their fishing trips they will regurgitate food for the chicks.

Parents swap between tending the nest and hunting for food. Initially these shifts last 11-14 days.

At 3 weeks old the chicks will join a creche. Only two-thirds of chicks will reach this stage of their life.

By 7-9 weeks old the chicks are ready to take to the sea for the first time.

After they take to the sea they will often not return to the breeding grounds until 3-5 years old when they reach sexual maturity.

They are one of only two penguins to breed in Antarctica with the other being the emperor penguin.

Behavior

These penguins are highly sociable and gather in colonies with tens of thousands of individual birds. This group living arrangement offers protection against predators.

Summer is spent on the land where they will breed before they take to the sea in winter to breed.

They will walk across ice but when enough snow coats it they will slide across the ground on their belly.

When swimming they reach speeds between 4 and 8 km/h (2.5-5mph). They may remain underwater for up to six minutes at a time.

Most of their dives take place during daylight to ensure they can see predators. As such they will spend winter in a northerly enough area to ensure they can continue to hunt.

Adelie penguins undergo a migration.

Predators and Threats

Natural predators of the Adelie penguin include leopard seals and skuas. Skuas primarily take eggs and chicks.

When entering the water a group of Adelie penguins will gather. They then wait for an individual to fall or they may push it in to the water. The rest of the group will then wait to see if that one is captured by a predator.

Overall the population of the adelie penguin is increasing. In areas where they have been decreasing the populations now appear to be stabilizing.

This is threatening to reverse a result of climate change which is causing decreases in the coverage of sea ice.

Oil spill are a threat to this species. They are further threatened by the presence of research stations and the movements of planes which reduce their available nesting sites.

Their food supplies are heavily impacting by fishing.

Quick facts

Adelie penguins were first described for western science in 1840 by a French Antarctic expedition led by explorer Jules Dumont d’Urville.

They are part of the group of three penguin species known as the brushtail penguins. The other two are the gentoo penguin and chinstrap penguin.