The horned puffin (Fratercula corniculata) is an auk found in the North Pacific Ocean, including the coasts of Alaska, Siberia and British Columbia. It is a pelagic seabird that feeds primarily by diving for fish. It nests in colonies, often with other auks. It is similar in appearance to the Atlantic puffin, its closest relative of the North Atlantic, but differs by a "horn" of black skin located above the eye, present in adult birds. The horned puffin's bill, which is larger than those of other puffin species, is red at the tip and yellow at the base. In summer (breeding) plumage, the bill's outer layer – the rhamphotheca – grows in size and turns bright yellow with a dark orange tip. The size and color of the rhamphotheca helps to attract a mate. The brilliant outer layers of the rhamphotheca are shed in late summer, as the face reverts to a gray and black color, and the legs and feet fade to a pale fleshy color. This phase is referred to as eclipse plumage. The puffin's bill has fluorescent properties that are also used to attract a partner. Puffins can see ultraviolet rays, allowing them to spot luminescence on the bills of other puffins during the courtship display.