It's a cold life being a king penguin chick

King penguin chicks on the Crozet Islands.
Photo by StormPetrel1. Some rights reserved.

SUBANTARCTIC - They may look warm and fuzzy, but scientists have shown that king penguin chicks are able to get very, very cold - and this ability probably helps them to survive through the lean, mean winter.

Scientists from the University of Strasbourg, France, studied heterothermy - the ability to survive despite large drops in body temperature - in king penguin chicks on the subantarctic Crozet Islands.

They did this, New Scientist reported, by inserting temperature sensors into several organs of 10 chicks (hmm ... I don't want to think about how they did that). The penguins were then left to go about their daily lives for about seven months. The scientists' findings were published on 16 August in the journal Nature Communications and show that parts of the chicks' bodies dropped by up to 15.7°C when they were inactive, local temperatures fell or when they were fed cold meals.

By allowing their body temperature to drop, the chicks appear to be able to conserve energy when they need to. The scientists said that king penguin chicks are able to fast for up to five months in winter, and during this period they show marked heterothermy.

The scientists also said that the heterothermy they had observed the penguins, who can weigh 10kg before fasting, is "remarkable" for a bird of their size and "may account for its unrivalled fasting capacity among birds".

Source
Penguins don't freeze, but they do get very, very cold, 19 August 2011, New Scientist

Nature Communications citation
Heterothermy in growing penguins. Götz Eichhorn, René Groscolas, Gaële Le Glaunec, Camille Parisel, Laurent Arnold, Patrice Medina and Yves Handrich. Nature Communications, 16 August 2011.