Check out these naked chicks!

16 11 2010

Progression of feather loss in affected chicks. Normal juvenile feathering ultimately grows in (see photo e)

A new study out in the journal Waterbirds reports on an apparent disorder in feather development in African Penguins (Spheniscus demersus) in South Africa and Magellanic Penguins (Spheniscus magellanicus) in Argentina. The abnormalities were first observed in 2006 among African Penguin chicks raised in the SANCCOB rehabilitation center in South Africa.
In both species, the normal sequence of feather development involves loss of the hatching down as a second downy coat grows in. That down is subsequently replaced by juvenile feathering. At no time is bare skin exposed during normal feather development.
In the rehab center, birds with the disorder lost their down and it was not replaced with new down or juvenile feathers for some weeks, leaving the birds looking like plucked chickens for an embarrassing period of time. The disorder did not lead to any deaths, and all the birds ultimately went on to grow normal juvenile feathers. However, affected birds took longer to attain a healthy weight for release, and were smaller overall than their unaffected counterparts, suggesting that the disorder has a detrimental effect on the bird’s overall energy balance.
A year after being detected at the rehab facility, the disorder was seen in Magellanic Penguins in the wild, and two years after that, in a wild colony of African Penguins. The number of birds affected in the wild colonies was far lower for both species than in the rehab setting. The authors of the journal article suggest that this is because of the close quarters in a rehab facility, which may encourage the spread of any infection involved in the disorder. The SEANET blogger would argue for consideration of another factor: birds taken in by a rehab center may not be the fittest individuals in the population, and may be more prone to disorders and diseases of any cause.

In any case, your blogger is also interested in seeing what further work is done on the subject. Hopefully, some diagnostics (skin scrapings or biopsies, for instance) will shed at least some light on this mysterious malady. There is a lot still to be discovered about this, and SEANET will spread the word as additional studies appear.





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