Tuesday, May 25, 2010
ICE ICE BABY MOULTING - UGG
Ice Ice Baby and our other adopted penguins are now finally leaving the colony on their winter migration. Their final destination is the coast of Brazil, and their journey will take them along the entire coastline of Argentina and Uruguay; an impressive journey indeed.
The last few weeks have been spent building up their fat reserves at sea, and then undergoing a complete change of feathers (called the molt). Ice Ice Baby spent most of the molt period in the nest. Even though egg-laying and chick-rearing is now finished until October, the nest offers valuable protection from the cold Autumn (Fall) winds, which can chill Ice Ice Baby to the bone during the molt.
The feathers provide excellent protection from the cold, but during the molt these feathers fall out, leaving Ice Ice Baby with patches of bare skin. Eventually the new feathers grow in to replace the lost feathers, but it takes about three weeks to complete the process.
This has to be the most miserable month of the year for Ice Ice Baby; shivering in the cold wind with half the feathers missing, unable to go to sea to feed for almost a month, and with absolutely nothing to do except sit still to conserve valuable energy, thinking about how cold and hungry they are. I attach a photo showing a penguin just starting to loose his feathers. Thankfully Ice Ice Baby's ordeal is now over, and the most relaxing part of the penguin year is now beginning.
Near the north and south poles, the days are very long in summer, which means more hours of daylight for the penguins to catch food for their chicks. But in the winter the days become very short, so the penguins migrate northwards towards the equator in search of longer hours of daylight.
During the winter the penguins never leave the water, because the sea has everything they need. They feed, rest, and even sleep, bobbing about in the open ocean, 20 kilometres or more from the coast. Although the weather on land becomes very cold during the winter around the penguin colony, the ocean is so large and deep that the water temperature only changes by two or three degrees between summer and winter, so penguins do not migrate to avoid the cold. It is the longer hours of daylight during which they can fish which drives them northwards.
Penguins cannot fly for two reasons. Firstly, their wings are too small to be of any use in air, because they are adapted for "flying" in the water. Wings can only be good at one or the other, either good in air or good in water, because birds need large wings to fly in air, and small wings to swim underwater. Of course there are many birds that can fly, and swim underwater, but none of them are fast swimmers in water, because large wings cannot be flapped quickly in water. Around 60 million years ago, not long after the extinction of the dinosaurs, penguins gave up trying to fly in order to make their flippers perfect for use underwater, and the result is that penguins can swim 5 times faster than any waterbird that flies.
The second reason that penguins cannot fly is that they are too heavy. Bones are heavy, so birds that fly have hollow bones filled with a honeycomb of air pockets and thin bone filaments. Such bones are rigid enough to fly, but fragile, which is why birds break their wings so easily. Light weight also means that the bird has difficulty diving underwater, without bobbing back up to the surface like a cork.
Once again, by giving up flight, penguins were able to turn their hollow, fragile bones into strong, solid bones. This not only makes their bones strong enough to survive being bashed against rocks every day, but also means that penguins can remain underwater with ease, without bobbing up to the surface like ducks and cormorants do.
Birds that fly suffer huge handicaps in the water: large cumbersome wings, excess buoyancy that makes diving difficult, and fragile bones. By giving up the power of flight, penguins have got rid of all these handicaps, and have dominated the southern oceans for around 60 million years. Despite their small size, penguins are amongst the southern ocean's top predators. They flap their small flippers rapidly to propel themselves at up to 20km per hour, steer using their feet as rudders, and can dive to over half a kilometer below the surface. No seabird on Earth is so well adapted to life in the ocean.
Being such good swimmers, migrating from the southern tip of South America to Brazil each year is an easy task. Indeed, with nothing else to do except swim, eat and sleep, the next four months are like a winter vacation for the penguins.