The Family Alcidae consists of seabirds commonly known as auks, including puffins, guillemots, murres, and auklets. These birds are adapted for diving and swimming, using their wings to "fly" underwater in pursuit of fish and other marine prey. Most species have compact, streamlined bodies, short wings, and webbed feet that aid in swimming, while their flight in air is rapid but often laborious. Alcidae are typically found in cold northern oceans, nesting in colonies on cliffs or rocky islands. They are socially gregarious, often forming large breeding colonies, and play an important role in marine ecosystems as mid-level predators.