Molto Bene: Penguin Molt Cycles

Penguin Molt Cycles

Exciting stuff huh? I can understand why you will need some convincing. So here goes.

Feathers are protein. Not as dense as muscle but a substantial investment when one's body is completely covered in it. Imagine if you had to regenerate your skin all in one go at least once a year.

Go ahead, grab a pinch of your skin between your fingers. Feel the thickness and the heft. Surprisingly, it is comparable to the thickness and heft of the insulating layer of feathers on a King Penguin. These creatures swim in some of the coldest seas on the planet, often a couple of degrees below freezing (Yes, below. The water can get that cold and stay liquid because of the salinity which prevents the formation of crystals until it gets even colder).

I know how cold it is because I went for a swim in Antarctica. Well, not strictly a swim, more like a crazy dash up to my neck and back out before the high pitched scream I was emitting did permanent damage to my hearing. We're talking voice-changing cold if you know what I mean.

Anyway, enough of me and my bid for the Vienna Boy's Choir. Penguins are hatched with a downy coat that covers everything except their feet, eyes, beak and anus. A place to see out of, a place for nutrients to go in and out and a way to walk without gumming up the apparatus and tracking stuff in on the rug. Other birds have bare patches between tracts of feathers to allow them to radiate heat off their bodies. Penguins can't afford to lose heat. If they do get hot they head to the water or engage in gular flutter (another exciting topic we'll skip for now. Think panting like a dog). A Penguin's feather tracts are continuous. This is the bird version of sea otter fur. The feathers are so tightly packed that water can not get to the skin. Yeah, that's right, WATER cannot get between the feathers! So when I said it is about the thickness and heft of your skin, I wasn't joking.

As the baby penguin grows it adds more downy feathers. The hard-working parents aren't just feeding a chick, they are supplying a feather factory too. That takes a lot of krill. A lot. So the chick grows bigger and bigger until it even surpasses the weight and girth of the parents. Why? Because now it is going to throw away all that hard work and molt into adult plumage. When they are sufficiently fat (see the picture) they re-route those food resources from bodily growth and development into making feathers.

The old baby stuff gets pushed out from underneath and falls off leaving funny looking, temporary Mohawks, chest hair or afros. Seems a waste, but they need the first downy coat for survival on land and the second sleek plumage for life in the cold, cold seas.

When the old downy coat is gone they are too. They enter the sea where they are now responsible for their own feathers. Until they reach the next stage they work at fluffing and oiling the feathers to keep them working correctly. The oil comes from a gland at the base of the tail called the uropygial gland. Found on the pygostyle (pronounced PIG-O-STYLE, Ha Ha!) It doesn't look very attractive either (see picture).

They press the gland with their bill which causes it to leak a clear oily liquid. Using the bill they painstakingly dab and swipe transferring oil from the gland to all their feathers (Remember how many that was? I never gave you a count, but water can't get to the skin. Remember that). If the feathers don't get a coating they lose the repellency and water dampens them and they droop towards the skin making cold patches. Brrrr!

So depending on the species, they spend a year or several at sea eating krill, fish or squid, making uropygial oil and storing up fat. The fat is for the next stage. At some point the old feathers get worn down and need to be replaced. This part is tricky. They must come onto land and do nothing for days on end while they push out the old adult feathers. To go and feed in the sea at this point would expose them to killing cold. The old feather come out in messy patches. Compared to the usual, sleek, well groomed look, at this stage they look like they have mange or something.

The feathers coming in are the same color as the ones on top so they just look messy and diseased, but aren't. When I went ashore at a King Penguin colony the first time I saw these curved little white things all over the ground. Honestly, my first impression was "where did all these big toenail clippings come from?" It took me a while to realize no one was doing pedicures on the beach and saw that they were feathers. They were everywhere. There were small drifts surrounding rocks and sleeping elephant seals.

That's when it hit me, molting is a major life activity for birds. It uses up a huge amount of stored fat. I suppose a bird could even starve to death molting. The penguin story makes the whole process look more extreme, but I realize this is a time of vulnerability that compares with reproduction and rearing. Molting is a big deal.