How hormones affect penguins' suits
In a traumatic three weeks they shed their old feathers and develop their
new ones. In that time they cannot swim and therefore cannot eat.
Dr Belinda Cannell, who has been watching the behaviour of Little Penguins for many years, is looking into the hormonal changes behind the moulting of Perth's penguin colony on Penguin Island.
The change is dramatic because the birds switch from rearing their young to looking after themselves in order to build up fat to see them through the moulting.
"If they swim during that time, as the new feathers push the old ones out, they can drown as their feathers get waterlogged because there's no oil in them at that stage," said Dr Cannell.
In collaboration with Professor Graeme Martin of UWA's Faculty of Agriculture, Dr Cannell is looking at how the levels of the hormones thyroxine and prolactin affect reproduction and incubation behaviour, fat deposition and feather synthesis in the birds.
She suspects that thyroxine is important in the change that penguins experience when moulting -- from the rapid gaining of fat in preparation for the moulting and then the production of replacement feathers.
She believes that low thyroxine levels are needed to deposit fat and high thyroxine levels are needed to produce feathers. How the birds' hormone levels change to bring this about is one subject of her research.
The 12-month study is funded by the Australian Research Council.
The penguin file
We have a significant colony of Little Penguins on Perth's doorstep.
About 1000 of them live on Penguin Island off the metropolitan coast and they are pretty special. Here are some facts about our own penguins:
- they are the smallest species of penguin in the world
- the Perth colony is the most northerly nesting spot in the world
- the Navy "keeps an eye on" a small group of penguins on Garden Island
- it is unique that such a population of penguins lives so close to a major city
- during the last pilchard plague, the penguins had a feast
- unlike other Little Penguins, the Perth colony commonly broods twice a year instead of once
- the Leeuwin Current affects the penguins' breeding -- in strong-current years they breed later and once rather than twice in that year
- some of the colony are in a CALM-built enclosure called the Penguin Experience where visitors can see them in an above-ground pool with clear sides.
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