Adélie penguin

Adélie penguins eat krill, which are tiny shrimp-like animals.

They also eat small fish. They dive under the water to catch their food.

Adélie penguins eat krill, small shrimp-like animals, along with fish and other tiny crustaceans called amphipods. What they eat depends on where they feed.

Near the colony, within about 20 kilometers, they catch mostly fish, amphipods and a small kind of krill called crystal krill. Farther out to sea they mostly eat Antarctic krill. Parents carry the food back in their stomachs and bring it up for their chicks: a meal can weigh 300 to 650 grams.

Diet varies with foraging location. The Australian Antarctic Division reports that meals caught within about 20 kilometers of the colony are mainly fish, amphipods and crystal krill (Euphausia crystallorophias), while offshore meals are mostly Antarctic krill (Euphausia superba). Meals fed to chicks range from about 300 to 650 grams depending on chick size.

The IUCN notes that Pygoscelis penguins are major consumers of Antarctic krill and move marine nutrients onto land in their guano. When pack ice has not yet broken up in spring, the nearest open water can be far away, and Adélies may have to walk more than 50 kilometers across the ice to reach the sea.

Adélie penguins nest close together in big groups.

They sometimes take pebbles from their neighbors' nests! Leopard seals and birds called skuas are dangers for them.

Adélie penguins nest in big, busy colonies. On Shirley Island near Australia's Casey station, about 40,000 breeding Adélies crowd onto less than one square kilometer.

Pebbles are precious, and Adélies often steal rocks from other penguins' nests when their owners are not looking. Their main predators are leopard seals, and skuas, which take eggs and chicks from the colony. Each penguin returns to the same nest, and the same partner, if it can.

Adélies are colonial breeders. The Windmill Islands near Casey station hold the third-largest population in East Antarctica, and Shirley Island alone supports about 40,000 breeding birds in less than one square kilometer. The IUCN's chinstrap penguin assessment notes that colonial penguins are more vulnerable to predators in very small colonies.

Nest stones are a limited resource, and stealing rocks from neighbors is common, as researchers studying 45,000 automatic-camera photos recorded. The main predators are leopard seals at sea and skuas, which take eggs and chicks. Because Adélies breed on land in summer, scientists know far more about this part of their lives than about winter in the pack ice.

There are millions of Adélie penguins.

Scientists count them and watch them with cameras. In some places there are more, and in others fewer.

The Adélie penguin is listed as Least Concern. The IUCN's 2020 assessment estimates about 10 million adults, and overall their number was going up.

Near Australia's Casey station, colonies grew from about 30,000 breeding pairs in the 1950s to nearly 200,000 today. But near Mawson station, one large population fell by 43 percent in about ten years, the Australian Antarctic Division reported in 2022. Scientists count penguins from helicopters and photos, and automatic cameras watch colonies all year. The IUCN lists fishing, disturbance by people, pollution and habitat changes linked to climate as threats.

The IUCN's 2020 global assessment lists Pygoscelis adeliae as Least Concern, with about 10,000,000 mature individuals and an increasing trend. Listed threats include fishing and harvesting of marine resources, human disturbance from recreation and research work, pollution and climate-driven habitat shifting.

Trends vary locally. In the Windmill Islands, the Australian Antarctic Division reports growth from about 30,000 breeding pairs in the 1950s to nearly 200,000; there, colonies that have filled their available breeding habitat have stopped growing, while those with space left continue to increase. By contrast, the Australian Antarctic Division reported in 2022 that a large population off the Mawson coast had declined by 43 percent over the previous decade, a loss of about 154,000 breeding birds across 52 islands; its scientists think the fall was triggered by five years of extensive summer sea ice near the colonies in the mid-2000s. Long-term monitoring at Béchervaise Island near Mawson, aerial counts and year-round camera networks track how the penguins respond to changes in their ecosystem.