Nature up close: Adélie Penguins

An Adélie penguin.

NASA

By “Sunday Morning” contributing videographer Judy Lehmberg.

Is there anything cuter than a penguin? Well, maybe. But they rank at the upper reaches of the cuteness scale. From their tuxedoed appearance to their waddling way of walking, they bring a smile to my face.

Adélie penguins are one of only a few penguin species who are true Antarctic penguins. They spend their entire lives either on Antarctica or in the water around the continent. They are second only to emperor penguins in how far south they nest, which is the primary reason they spend time on land. They are superbly adapted (both physically and behaviorally) for their cold, windy environment.

Adélie penguins have fusiform-shaped bodies and are believed to be the best-adapted animal for moving through water. They, like all penguins, are flightless in the air, but in a sense they fly through the water. Most birds have hollow, extremely lightweight bones to help reduce their weight for flying. Penguins have more solid bones, and many of their wing bones are fused, including their wrists and elbows so they can be used to “fly” in the water more efficiently. A flying bird only gets forward thrust while its wings move downward, not upward. Since their weight is supported by water, penguins get thrust both when their wings are moving downward and upward, making them extremely efficient and fast swimmers.

Losing the ability to fly in the air occurred in various bird species due to many environmental pressures, but penguins simply evolved to fly underwater. This ability to penetrate the rich waters of the Southern Hemisphere opened up a vast food supply to these very successful birds.

One aspect of penguin biology we may not think about is the fact that they rarely come in contact with fresh water. They swim and feed in salt water. The land they nest on is like a desert, because the only water there is almost always frozen. Their body cells cannot survive in the high salt concentrations in the surrounding oceans. The only reason they can survive in highly saline conditions is they have glands above their eyes which concentrate and excrete excess salt. These supraorbital glands have a large network of capillaries, and function much like kidneys to concentrate and excrete excess salt. Without these glands, penguins could not survive.

adelie-penguins-rookery-noaa-nesdis-ora.jpg

Adelie penguins at a rookery.

NOAA NESDIS ORA

Another nifty adaptation they have is that they can control the blood supply to their feet and wings. When they are nesting and it gets really cold, they reduce the flow of blood to their wings and feet, thus retaining body heat that would be lost to the environment around those extremities. When they have been swimming for long periods of time, the underside of their wings appear pinkish, as blood is flowing to the wings to allow them to function and get rid of excess heat. So if you want to know if an Adélie penguin is cold, look at their feet: If they are whitish the bird is cold; if they are pink the bird is warm.

Penguin feathers are uniquely adapted to allow these birds to withstand extremely low temperatures. They have an unusually high density of feathers. Each feather is composed of a downy section near the body to retain body heat, and a stiff section at the tip to repel water and keep their body dry even when they are swimming. The stiff section of each feather is waterproofed when a penguin preens. They have a gland near the base of their tail which provides waterproof oil. The birds get oil from this gland with their beaks, and spend several hours each day covering their feathers with the oil, especially before they go in the water. Because they can’t reach their head and neck with their beak, they rub oil on the leading edge of their wing and then rub it onto their head and neck. As they preen they also fluff up their feathers so they can trap more insulating air in them.

If you’ve ever seen a penguin walking, it not only looks comical but inefficient. They don’t really walk, they waddle. Surprisingly, that waddle is 80% more efficient than walking. Another method they have of moving on land is “tobogganing,” when they get on their belly and slide over slick snow or ice using their strong feet and claws to propel themselves. Not only is it efficient, it looks like a lot of fun!  And as inefficient as it looks, penguins can walk over 60 miles if ice forms between the ocean and their nesting sites.

Like numerous other species, penguins are being affected by climate change. But because Adélie penguins only nest on land not covered by snow or ice, their population has actually increased in recent years. It has declined in some areas around the edges of Antarctica, especially on the West Antarctic Peninsula, which is one of the fastest-warming areas on Earth. However, their numbers have increased in the Cape Adare region of the Ross Sea.

Penguins can be difficult to count because they don’t hold still, but several recent studies place their population between ten and fifteen million birds, making them the most numerous penguins in the world.                   

Some Adélie penguin quick facts:

  • They were named by French explorer Jules Dumont d’Urville who named an island Adélie, after his wife, Adele. The Adélie penguin was first discovered on that island.
  • The longest distance traveled by an Adélie penguin is about 10,900 miles.
  • Adélie penguins are about 27 inches tall and weigh from 8 to 12 pounds.
  • They nest in the Antarctic summer in November to February in colonies of up to half a million birds or more.
  • They eat primarily krill and fish.
  • While swimming they pull their feet close to their bodies to become more streamlined, but they can stick a foot out to turn as much as 180 degrees in 1/5th of a second.
  • They build their nests only on land without ice or snow. The nest consists of small rocks, which are useful in keeping their eggs off the ground when snow melts. They often steal rocks from their neighbors.
  • The adults’ main predators are leopard seals, while the unguarded chicks and eggs are taken by skuas.

       
Judy Lehmberg is a former college biology teacher who now shoots nature videos.


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