A small (9 inches) tern, the Least Tern in summer is most easily identified by its black cap and white forehead, deeply-forked tail, black-tipped yellow bill, and dark wing tips. In winter, this species becomes duller on the head and face, becoming dark-billed and pale headed while retaining black eye-patches connected to a dull black hood. This species’ small size and yellow bill help distinguish it from other tern species occurring in its range. Male and female Least Terns are similar to one another in all seasons. The Least Tern breeds along coasts and large rivers across the United States. In winter, birds breeding in the U.S. spend the winter from Mexico south to southern South America. Other populations breed in Mexico, Central America, and parts of the Caribbean, many of which are non-migratory. Least Terns primarily breed sandy beaches, islands, and mud flats. In winter, this species may be found along beaches or in near-shore waters. Least Terns mainly eat small fish, but may eat small invertebrates, primarily crustaceans, as they become available. Least Terns may be most easily seen standing or walking along the shore or on the beach, where their dark wing tips and (in summer) yellow bill may be most apparent. With the aid of binoculars, it may also be possible to observe this species feeding by diving headfirst into the water. Least Terns are most active during the day.
Uncommon migrant in this region. Arrives mid-April, leaves mid-October. Breeding colonies occur on the lower Potomac and Eastern Shore from late May to early August.
The bird on the left is a juvenile female.
Collected By: Mr. Hamilton
Locality: Washington, DC (Carp Ponds)
Sex: Female, Juvenile
Catalog ID: 75367
The bird on the right is an adult male.
Collected By: Wm Palmer
Locality: Cobbs Island, VA
Catalog ID: 153320