Lowest temperature endured by a bird

The lowest temperature endured by any bird is an average temperature of -20ºC (-4ºF) by the breeding emperor penguin (Aptenodytes forsteri) on the Antarctic sea ice where the windspeed can vary from 25–75 km/h (16–47 mph).

“The means whereby Emperor penguins survive in harsh conditions are several remarkable physiological and behavioural adaptations, all arising from the need to minimize heat loss and the expenditure of energy. Their body size and shape give a relatively low surface-to-volume ratio, and the flippers and bill are 25% smaller as a proportion of body size than in any other penguin species. Heat loss is further reduced by extreme proliferation of the blood-vessel heat-exchange system, which is twice as extensive as that of any other penguin. Blood vessels flowing to the feet and flippers lie very close to the veins returning blood to cool, resulting in minimal heat loss. Emperor’s also recover heat in the nasal passages through exchnage between inhaled cold air and warm air to be exhaled (about 80% of the warm air is retained), and by excellent insulation provided by the very long, multi-layered, high-density feathers that completely cover their legs.” – Firefly Encyclopedia of Birds, 2003, edited by Christopher Perrins