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Flightless Friday - Pygoscelis adeliae Edition

New series! I am proud to introduce Flightless Friday, which will start by covering all 17 species of penguin, and then move on to the extant ratites from there. This is my first animal series about birds, and I’m looking forward to learning all the new things!

The Adélie Penguin (Pygoscelis adeliae) is a species of penguin that can be found in the coastal areas of Antarctica. Adélie Penguins were named in 1840 by French explorer Jules Dumont d’Urville after his wife, Adéle. He also named Adélie Land, which is an Antarctic territory claimed by France but not diplomatically recognized by most other countries. The penguins live at the edge of what is called “fast ice,” because they follow the sun in their migration. During Antarctic winters the sun doesn’t rise south of the Antarctic Circle, but sea ice extends the livable territory miles and miles north. Living on this edge means that Adélie Penguins have sunlight in the winter, and retreat back toward land as the ice retreats with the onset of summer.


As penguins go, Adélie Penguins are medium-sized, standing up to 28 inches (71 cm) tall and weighing up to 13 pounds (6 kg). They are black and white, with white-rimmed eyes and a pale ring around the base of their bills. Their bills have a dark red tone to them, although they often appear black from a distance. Juveniles have more blue in their black feathers than adults, and chicks are downy gray. Black and white coloring is a good example of countershading camouflage, which means that in the water the penguins blend in with the depths when viewed from above, and blend in with the surface when viewed from below.

The diet of Adélie Penguin consists mainly of different kinds of krill, silverfish, and squid, depending on the season. They are extremely fast swimmers, able to reach speeds of over 9 miles per hour (15 kmh) and diving to depths of up to 574 feet (175 meters), though they mostly forage at shallower depths. Research conducted on fossilized eggshells indicates a shift in diet about 200 years ago, when Adélie Penguins began to eat more krill. It’s likely that the over-hunting of other krill predators like seals and whales reduced the competition for this food source, leading to an abundance of krill that the penguins adapted to take in.


The breeding season of Adélie Penguins occurs during October and November, where they construct nests made out of small stones. Nest construction is part of the courtship ritual, and while mated pairs end up finishing the nests together, males are not above stealing stones from each other during initial construction. The females will lay a clutch of one to two eggs in the nest, and then take turns incubating with their mates. The non-incubating parent will forage for food, while the incubating parent does not eat. Incubation period is about 35 days. After the chicks reach 3 weeks of age, they are gathered together in what is called a créche, which helps protect them until they are ready to fledge about a month later (safety in numbers!). Adélie Penguins often return to the colony of their birth in order to mate.


Adélie Penguins are preyed upon by skua, Leopard Seals and orcas, and because they live most of their lives on sea ice, they are threatened by climate change. Researchers have observed Adélie Penguins engaging in a wide variety of sexual behavior, which early scientists anthropomorphically categorized as sexual deviance. This behavior includes homosexual mating, necrophilia and abuse of juveniles and chicks. Also observed is a behavior that may be an example of prostitution among animals, as females in mated partnerships would copulate with other males in exchange for stones to add to the nest. In other cases, the females would lead the other males on, engaging in a courtship display but stealing stones without finishing the ritual by mating. It’s also possible that the primary purpose behind this behavior is not to secure more stones, but to evaluate potential partners in the event that the females’ current mates were to die.


Source for all images used in this post.

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