The Adélie penguin (Pygoscelis adéliae) is a medium sized penguin weighing between 3 – 6kg and stand at 70cm tall. It is one of the most widespread penguins in the Antarctic; they are 1 of only 2 true Antarctic residents. They largely resided close to the sea around the coast and only venture to further in ice-free land to breed. The Adélie penguin diet consists of eating small sea creatures such as krill, small fish and squid. They generally hunt in shallow waters but can occasionally been seen going deeper and can dive as deep as 575 feet. The Penguins have a unique appearance; their body is half and half with black plumage on the back side of the body and white plumage on the chest going from the front of the throat to the top of the legs. Its head is fully black with a striking feature of a white ring around its eyes. It has a short thick, black beak with dark red merged in and its legs are a light pink colour; its flippers also contain a light pink and white on the inside but have back plumage on the outside.
Between early October and early November, the Adélie penguins return to the rocky landscapes in the Antarctic; the male Adélie will arrive a short time before the females and start the construction of the nest. The nest for the Adélie is built with the best pebbles and stones they find on the dry land. They will search around the perfect stones and either roll them back to their nest or if they are small enough carry them in the beak. If a male sees a better stone in another nest he may be sneaky enough to steel it from the other male; This can cause fighting between males and generally gets very aggressive. Some of the males build their nest on the snow and wait for it to melt away but others hollow out a hole in the snow and build their nest in the hollow. They will build the nest on sloping bits of land so that when any ice or snow melts the water will run down and not flood the nest; The males build most of the nest with the females chipping in during courtship.
The Adélie penguin will fast for 3 weeks before egg laying commences. This is thought to be because the Adélie will return to their colonies later than other breeds as they have a longer distance to travel to reach their breeding grounds; Meaning the time they have for breeding is shorter than other penguins. This suggests that the feeding grounds for the penguin are too far away to try and travel to while the courtship and breeding is going on. It is also thought that they fast before laying eggs because it causes less stress in the penguins. The harder the Adélie works the amount of corticosterone release increases and causes the bird to become stressed, it can also be caused by unpredictable circumstances which will come up if a penguin is out hunting in the water, it will be focused on finding food and not becoming food for something else.
The Adélie penguins are monogamous for each breeding season, staying with the same partner however they may choose a different mate each year; in some studies, it has been shown that some males and females stay monogamous for many years but it is not regular enough to say they are monogamous animals. The males perform a display for the females. The male will start by standing on a pile of pebbles which he has collected to impress and also will become the nest, he will then stretch his neck and head upwards while pointing his bill vertically and vibrate his chest. He will then clap his beak repeatedly and stretch out his wings and flap them simultaneously. This is referred to as “ecstatic display” (Wilson 1907). If a female is interested she will then approach the nest and bend forwards with her beak at a 30-60-degree angle from the horizontal, and slowly turns the side of her head to the male; this is known as “bowing” (Sladen 1958). The male will then mimic this posture but have his feathers ruffled and his pupils lowered as to not seem a threat. the pair will then remain bowing to each other. Then the male will sit in the nest and scrape around with his feet, rolling pebbles about, this is referred to as “nest scraping” and “rearranging” (Spurr 1975). This then gives way to the female who settles into the nest; the male will lower its head, vibrate its flippers and jump onto the back of the female. She will then raise her beak and tail as they begin to copulate; they will rub the beaks together during copulation.
The egg laying will takes place around early November to early December where they will lay 2 eggs however, often if an egg is lost soon after the early laying, a third egg will be laid. There is an interval between each egg being laid of around 3-4 days. the incubation period will last around 34 days for the first egg and 33 for the second; it takes less time for the second egg as they are generally smaller than the first egg laid. The males will take control of the first incubation period allowing the females to go off for the first foraging; which will last around 10 days. Sometimes during this first foraging trip, a female will mistime her return to the nest and take much longer foraging, between 20 to 25 days. This causes problems in re-productivity in the Adélie during initial incubation; the females take too long to return to the nest and this in turn makes the male desert the nest due to exhaustion and hunger (Davis, 1982; Ainley at al., 1983) this causes the egg to freeze and die. After extensive research they have realised that the fasting period during initial breeding has no correlation to the amount of time the females spend on their first foraging trip; therefore, the females that take longer to get back aren’t doing so because they have had much long fasting.
The male and female Adélie can often been seen together on their territory (generally includes the nest and a small space around it) and from time to time the will show a “mutual display” (parade mutelle,” after Sapin – Jalpistre and Bourliere. 1952). These mutual displays will often be “Loud and Quite Mutual Displays” (Sladen 1958); these consists of both penguins standing in front of each other near or on the nests, raise their heads, wave it from side to side, then let out harsh vocalisation. They will also do “mutual epigamic display” (Roberts 1940); Both of them will bend towards the ground while thrusting their beaks at each other then they will stand up and wave their heads which are held vertically. This can also be called “bowing”. These types of displays are often shown during nest reliefs during the incubation period and also while the penguins are brooding.
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