Chinstrap penguins live at sea for most of the year, feeding in open water north of the polar ice. When swimming at high speed, they often leap clear of the water, or “porpoise,” which allows them to breathe and coats their bodies with a layer of air bubbles, reducing friction with the water.
In November, chinstrap penguins return to their breeding colonies on ice-free shores in Antarctica and on islands in the Southern Ocean. Here, they make their nests by scraping together small stones to form a shallow cup. Chinstrap penguins tend to be more aggressive than other species, particularly when breeding.
They steal stones from their neighbors and chase away any larger penguins that attempt to nest nearby. The female lays two eggs, and her chicks fledge and set off for the sea by February or March, when the southern fall begins. Chinstrap penguins feed almost entirely on krill, and their current population growth, like that of Antarctica’s krill-eating seals, may be linked to the decline of krill-eating baleen whales.