The American dipper (Cinclus mexicanus), also known as a water ouzel, is a stocky dark grey bird with a head sometimes tinged with brown, and white feathers on the eyelids that cause the eyes to flash white as the bird blinks. It is 16.5 cm long, has a wingspan of 23 cm. It has long legs, and bobs its whole body up and down during pauses as it feeds on the bottom of fast-moving, rocky streams. It inhabits the mountainous regions of Central America and western North America from Panama to Alaska. This species, like other dippers, is equipped with an extra eyelid called a nictitating membrane that allows it to see underwater, and scales that close its nostrils when submerged. Dippers also produce more oil than most birds, which may help keep them warmer when seeking food underwater. The song consists of high whistles or trills peee peee pijur pijur repeated a few times. Both sexes of this bird sing year round.