A flamingo stands on one leg. Some believe that the bird turns off one side of its brain when sleeping. It tucks in the leg controlled by that side of the brain. The long legs also demand extra work from the heart while circulating blood. And when it stands in cool water, the heart has to circulate more blood to keep the legs warm. By taking one leg out of water, it reduces the load on its heart. This also helps conserve body heat. Standing on one leg could help it to camouflage itself: a single leg merges with the reeds and grasses.