Birds
Adélie Penguin
Pygoscelis adeliae · also called Adélie penguin
The Adélie penguin is the one that looks the way a penguin is “supposed” to look — small, upright, black-backed and white-fronted, with a white ring around a beady eye. It lives right around the Antarctic coast, walks astonishing distances across the sea ice to reach its nesting grounds, and spends the breeding season in a running feud with its neighbours over pebbles.
Overview
Adélie penguins breed on ice-free rock all around the Antarctic continent and its islands — often at the same colony sites for thousands of years — and feed in the surrounding pack ice and open ocean, mostly on Antarctic krill and small fish. They are the smallest Antarctic penguin and among the most aggressive, quick to jab with the bill and beat with the flippers.
Stone wars
The Adélie’s nest is a bowl of pebbles on bare ground. The stones lift the eggs above the summer meltwater, so they genuinely matter — and good stones are scarce. Penguins steal them constantly from unattended nests, and males present stones to females in courtship.
The long march
Because colonies are on rock and food is in open water beyond the fast ice, a breeding or commuting Adélie may cross 30–50 kilometres of sea ice on foot, walking or tobogganing on its belly.
A climate barometer
Adélie colonies are collapsing on the fast-warming Antarctic Peninsula (some by over 90%), where gentoo and chinstrap penguins are replacing them, while numbers are growing in the colder Ross Sea. Overall the species is still around 10 million pairs and increasing — but it is a closely watched signal of Southern Ocean change.
Status
The Adélie penguin is Least Concern and increasing overall, despite sharp regional losses. Its predators are the leopard seal at sea and the south polar skua at the nest.
Adélie Penguin: common questions
Why do Adélie penguins fight over stones?
An Adélie penguin's nest is a shallow bowl of small pebbles, and the pebbles matter — they lift the eggs a few centimetres above the ground so that when the summer thaw comes and meltwater runs across the colony, the eggs and chicks stay dry rather than being chilled or drowned. Suitable stones are a limited resource in a colony of tens of thousands of birds, so penguins are constantly stealing them from any nest whose owner has stepped away, carrying them off one at a time in their bills. Males also present stones to females during courtship, and a good pile of pebbles is part of what makes a male attractive. Nest-stone theft is one of the most reliable pieces of drama in an Adélie colony.
How far do they travel to breed?
It depends on the ice. Adélie penguins breed on bare rock, which in Antarctica is only exposed along certain stretches of coast, and they feed in open water, which in early spring may be far offshore beyond a wide belt of fast sea ice. So a bird returning to a colony to breed, or an adult commuting to feed chicks, may have to cross 30 to 50 kilometres of ice on foot — walking upright, or lying on its belly and pushing with its flippers and feet in a fast slide called tobogganing. Once the sea ice breaks up later in the season, the journey gets much shorter.
Are Adélie penguins affected by climate change?
Yes, strongly, and in both directions depending on the region. On the Antarctic Peninsula, which is one of the fastest-warming places on Earth, Adélie colonies have collapsed — some by more than 90% — as sea ice retreats, snowfall increases (burying nests), and their krill supply shifts, and they are being replaced by the more temperate-adapted gentoo and chinstrap penguins. In the colder, more stable Ross Sea region, Adélie numbers have grown. The species overall is still numerous and increasing, but it is a closely watched indicator of how the Southern Ocean ecosystem is changing.
What eats an Adélie penguin?
In the water, the main predator is the leopard seal, which patrols the ice edge at colonies and takes adults as they enter or leave the sea; killer whales also take some. On land and on the ice the eggs and chicks are vulnerable to south polar skuas, which patrol colonies for any unguarded nest, and to sheathbills. Adult Adélies are quick and aggressive on land and can drive off skuas, but the period when parents must leave chicks to forage — when the chicks gather in protective groups called crèches — is when skua predation peaks.