Scientists are baffled by a wildlife mystery: Why are some penguin chicks losing their feathers?
The illness known as feather-loss disorder has hit colonies on both sides of the South Atlantic and no one knows what is causing the condition.
Researchers from Washington, South Africa and Argentina have just published a paper into the phenomenon of 'naked' penguins.
Not-so-happy feet: A 'naked' penguin stands forlornly before the camera after baffling researchers with a sudden loss of feathers
It's a bit breezy in here... One of the forlorn 'naked' penguins leaving scientists baffled as to how they are losing their feathers
'Feather-loss disorders are uncommon in most bird species,' said P. Dee Boersma of the Wildlife Conservation Society and Washington University, who has studied Magellanic penguins for more than three decades.
'We need to conduct further study to determine the cause of the disorder and if this is in fact spreading to other penguin species.'
Feather-loss first emerged in 2006 in a colony of black-footed penguins at a bird rehabilitation centre in South Africa, according to Science Daily.
At least we have each other: Two of the featherless penguins huddle together for warmth as scientists try to figure out what is wrong
Disorder: A Magellan penguin who still has his feathers off the Atlantic coast of Argentina
Almost 60 per cent of the chicks lost their feathers, followed by 97 per cent there in 2007, falling to one in five in 2008.
Researchers also noted that while feathered chicks sought out shade in the hot midday sun, featherless chicks remained in the sun's glare. Many died during the research.
In four studies along Argentina's coastline in 2007, researchers observed the disorder in the chicks of wild Magellanic penguins which are closely related to African penguins.
In every case across the ocean, penguin chicks with feather-loss disorder grew more slowly than those with feathers.
Featherless chicks were also smaller in size and weight. Both were due to the increased energy spent in keeping warm in the absence of an insulating coat of feathers.
So far, the possible causes include pathogens, thyroid disorders, nutrient imbalances, or genetics.
Boersma told Science Daily: 'We need to learn how to stop the spread of feather-loss disorder, as penguins already have problems with oil pollution and climate variation.
'It's important to keep disease from being added to the list of threats they face.'(dailymail.co.uk)