The birds hoover over the water and dive to catch their prey. They will eat almost any type of fish, if of the appropriate size. The interior least tern is one of three subspecies of least terns and is the smallest member of the tern family. The interior least tern is a swallow like bird eight to nine inches long with a 20 inch wing span and is distinguished by its glossy black head. The interior least tern has a gray back and wings, and a white underbelly and forehead.
Males usually have orange webbed feet, while females have yellow webbed feet.
Both the male and female bills are yellow-orange with a black tip. The interior least tern is known for its graceful and buoyant flight. The interior least tern was placed on the Endangered Species List in 1985, while its relative, the California least tern, was federally listed in 1970. The severe decline in interior least tern populations is largely attributable to river channelization, irrigation diversion and damming along the species prime nesting ground. Interior least tern's nesting grounds consist of dry, flat, sparsely vegetated sand and gravel bars found within wide river channels.