Adelie Penguins - Pygoscelis adeliae
Facts, Biology and Adaptations

The most southerly breeding penguins along with the Emperor, found on continental Antarctica and sub-Antarctic islands.

  Why is this Adelie penguin on the ice?

Sometimes Adelie penguins have to travel as much as 100 kilometres (60 miles) across sea-ice to reach their nesting sites, though usually 20-40 is more usual. The ice has usually broken up by the time the chicks are hatched.

This guy here was an early arrival (the males arrive first) in spring at an Antarctic Island near the northern edge of the breeding range and only had about half a kilometer left to waddle and "toboggan".

Tobogganing is a way of getting around where there is smooth snow or ice. The penguin lies on its front and propels itself along using its feet, an efficient use of energy and one where the penguin can easily keep up with a running person.

 When do Adelie penguins start to nest?

Adelies winter on the pack ice where the air temperature is higher than on land and where they can find cracks in the ice to fish through.

In October, they begin to move south to their breeding grounds, the males arriving first to establish territories and nest spaces with the females arriving shortly afterwards.

These are some of the first males arriving back in the spring before the remainder of the sea-ice has broken away, taking a rest here before continuing on their journey.

 Why are these penguins hopping about on the ice?

These Adelies have a problem, they went out fishing at high tide and now. some hours later have returned. In the meantime the tide has gone out.

Still attached to the land is the "ice-foot" an ice step left behind as the tide rises and falls in the winter months to which the floating sea ice is loosely attached. When the sea ice breaks out, the ice-foot is left behind for a period of days to weeks before rising temperatures and the waves cause this to break off too. 

What was a short hop down for the penguins is now a step too high for them. I spent a couple of hours one afternoon watching and following an ever increasing number of penguins as they came back from their fishing trip. They wandered up and down the shore-line trying to find somewhere to get up, but to no avail. Eventually, the tide came back in and so they floated back up to the right level and were able to get back to their nests. The ice-foot broke off completely a few days later in a mild storm.

More of the Adelies stuck at low tide.

The ice-foot is more evident in this picture and the number of penguins is building up, by the time the tide was rising enough to float the grounded "bergy bits" that the birds are standing on, there were about 50 or so penguins standing around before they could get back up.

 Why is this penguin showing off?

What a handsome fellow!  This male Adelie is a bit late compared to the others around him who have in the main already paired and nested.

The males arrive at the breeding grounds first, find a good spot and then go through this display with much raucous calling and flipper waving to attract a suitably impressed female. (A similar ritual is re-enacted on Friday and Saturday evenings at bars and clubs the world over).

You can also see the half-feathered beak characteristic of Adelie penguins and how stocky and powerful they are despite their diminutive stature.

Like many penguin species, the male and females are physically almost completely identical and it is almost impossible to tell them apart by their appearnce, the behaviour at mating time however gives things away much more clearly.

 

 

 Adelie penguins (Pygoscelis adeliae) tobogganing

Tobogganing Adelie penguins (and a lone chinstrap in the fore-ground). All types of penguin that come across snow and ice can and will toboggan in this manner. It is a very efficient and rapid way of moving when the conditions are right - soft snow, but where the penguin only sinks a little way into it, needing less energy than walking the same distance.

The penguin lays on it's front and pushes its way forwards using its feet, the flippers are used for balance or sometimes as oars to help forwards movement. It can be a fast sprint to get away quickly or a more leisurely equivalent of a slow-jog over a long time period.

A considerable speed can be reached for short distances in this way, enough to out pace a running person.

 Penguin dive

Antarctic penguins run a constant risk when entering or leaving the water from the almost ever-present danger of their main predator, the leopard seal. Leopard seals tend not to chase penguins around in the open sea, but hang around the places where they jump into the sea from their nesting areas, or where they leave the sea again as this is gives much more productive hunting.

The penguins have a problem when going into the sea, they have to enter it to go fishing and to get places, but being the first one in means that they're first in line for a potential leopard seal attack. Hanging back isn't any better though as they may get left behind and end up jumping in on their own. What happens therefore is that they gather at the edge of the water becoming quite animated and jostling for position until one near to the edge gets pushed or jumps in - that's the signal for the rest, as the odds of survival are far greater when you're part of a large group which can confuse the leopard seal, they then all dive in in rapid succession.

 Parent penguin and chicks

Like many penguins, Adelies lay two eggs of which usually only one survives to fledge.

The parents take it in turns to incubate the eggs or go out to sea fishing and then later on when the eggs have hatched, they take it in turns to catch food for and feed the chicks or sit with the chicks on the nest. When the chicks are older and able to walk around and leave the nest, the parents will both go fishing together to supply the growing demand for food from the growing youngster/s.

The chicks left behind form loose collections of birds that stay close together in a group called a creche where they help defend to each other from marauding skuas and also the weather when the wind blows and temperature drops, huddling together gives them extra warmth and protection.

 Adelie penguin adaptations

One of the "classic" penguin species, the second most southerly after the Emperor, Adelie penguins breed in the far south, but leave it to head north with the onset of winter.

• Anatomical - Structures of the body.
• Behavioural - The manner in which animals move and act.
• Physiological - The internal functions of the animal from biochemical, to cellular, tissue, organ and whole organism levels.

  Adelie Penguin Anatomical Adaptations

  Compact shape, low surface area to volume ratio reduces heat loss.

  Very dense specialized feathers for insulation on land, a layer of fat under the skin provides insulation in the sea.

  Short wings reduced to flippers for swimming underwater, the musculature for those flippers is almost entirely held in the body where it can be maintained at a warm temperature more easily.

  Backward pointing barbs on the tongue to stop slippery prey escaping.

  Black above and white underneath makes it harder to see in the sea from underneath where predators wait. The colouration also helps in warming and cooling the penguin on land when they can turn the back or front to the sun according to whether they need to warm up or cool down.

 

  Adelie Penguin Behavioural Adaptations

  Migrate north to escape the harsh Antarctic winter at the end of the brief summer.
 

  Arrive in the south early in the summer season, to take best advantage of the seasonal abundance of food.

  Tobogganing sliding on their front while pushing with legs, saves a lot of energy on long journeys.

  Build a crude nest of stones to lift the eggs above ground level to prevent chilling from melting snow in summer.

  Gather at the ice edge in large groups before jumping in the sea in case of predators, this increases individual survival chances.

  Adelie Penguin Physiological Adaptations

  Muscle has large amounts of myoglobin to hold extra oxygen that can be used to generate energy more efficiently during a dive.

  A counter-current circulation system in the legs and flippers mean that these regions are kept above freezing but below the normal body temperature, so reducing heat loss. The feet and toes  are operated by muscles kept warm in the penguins body via string-like tendons.

  During a deep dive, the heart rate slows from 80-100 per minute down to about 20 beats per minute.

  Ability to cope with a high saline diet due to salt glands and kidneys that produce concentrated urine (like many seabirds, penguins can drink sea water and gain water).

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Picture credits: Header picture courtesy DepositPhotos under licence