Abstract
Four species of hummingbirds (Archilochus alexandri, Calypte anna, Selasphorus sasin and S. rufus) keep ther feet and toes in a special patch of downy belly feathers at low ambient temperatures (Ta), gradually expose them as temperatures rise and hold them fully exposed at high Ta when hovering and perching. Since the position of the feet depends on Ta, it probably influences the birds'' heat transfer coefficient.

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