Stead, P. J, Stafford, J, Ruttledge, R. F & Ruttledge, R. F / June 1969 – vol. 62, issue 6–244 Bill-length as a field-character of the White-winged Black Tern ? In his paper on 'Juvenile and winter plumages of the marsh terns' (Brit. Birds, 53: 243-252) Kenneth Williamson differentiated without qualification between the bill of the Black Tern Chlidonias niger as 'long, slender and looking slightly decurved' and that of the White-winged Black Tern C. leucopterus as 'short and stubby' (p. 249) and ... This article is only available to registered users.To read more, please log in or purchase a subscription.