Chlidonias nigra surinamensis (Gmelin)
Other Name.—Marsh Tern.
Description.—Size small; tail short, forked. Adults in summer: Head and underparts black, save under tail-coverts, which are white; upperparts gray; bill and feet red. Adults in winter and immature: White, with pearl-gray back and wings and dusky spots on head; bill and feet dusky. Length: 10 inches.
Range in Pennsylvania.—Irregular as a migrant throughout the Commonwealth; more frequently seen than other Terns about marshes and on small bodies of water; usually seen between April 25 and September 30. Though it is thus to be seen in midsummer irregularly, it is not known to nest in Pennsylvania at the present time.