Understanding Moulting and the moulting cycle
Moulting is the process during which feathers are replaced. It is necessary because penguin feathers, which form an insulating barrier between the bird and its cold marine environment and dually aid in the incubational processes of eggs and in the survivorship of newly hatched chicks at nest sites, do deteriorate with time and cease to perform these vital functions.
Like an ill kept wetsuit that has been damaged by the sun and the salt of the ocean – it must be replaced.
The dedicated pre-moult fattening period lasts about 35 days – a penguin must build up sufficient fat reserves (approximately a 30% weight increase) to be prepared to cater for metabolic requirements during the moult cycle. Depending on the food resource availability most penguins will overnight at feeding grounds – offshore, during this pre-moult period. Penguins arrive back to the colony to moult, fat and clumsy. About five days later their feathers suddenly stand up. This marks the beginning of the shedding phase of the moult cycle. During the synchronized moult season at Stony Point, which peaks in amounting numbers during December, each penguin is land-bound for approximately 21 days, and only once the new feathers form an effective insulation can penguins return back to sea long enough to replenish lost reserves.
During this fasting period the metabolizing of fat reserves results in rapid weight loss, and by the time a penguin returns to sea it weighs only 46% of its weight as to when it came ashore.
Moulting penguins usually congregate and remain motionless at the shoreline or landing stages at the colony during this summer occurrence. The coolness of the air that comes off the ocean's surface helps manage metabolic rates at a sustainable level. Initially a penguin loses muscular control over its old feathers and these fall out to be replaced by the new feathers. Once the moult phase is complete the penguin leaves the shoreline and has to return to the ocean and compete for dwindling food resources. They are absent from the colony for a period of about six weeks at sea recovering from the moult fast.
Penguins that have completed the moult phase are now dressed in clean 'starched' tuxedos.
Any unnecessary disturbance of moulting penguins during this highly sensitive period may jeopardize their future survival therefore it is imperative that all visitors who come to the colony during the summer period exercise a sustainable level of respect for these little creatures of the ocean so that they can prosper well into the future.
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