Trinidad and Tobago Field Naturalists' Club         Southeastern Caribbean Bird Alert         Trinidad and Tobago Rare Bird Committee
'Mystery Tern' (Sterna / Chlidonias sp.)
'Mystery tern' (Sterna / Chlidonia sp.) at Waterloo, Trinidad, 17 March 2002. Photos © by Floyd Hayes, shot with two different cameras at different angles. Note the black bill, dark facial patch, prominent carpal bar (probably indicative of immature), dusky primaries, red legs (partially obscured by mud), dark outer web of outermost retrix, and small size in comparison with Laughing Gulls (Larus atricilla) in bottom photo. To see the opinions of others, click here.

Clearly this an odd bird whose identity cannot be ascertained with certainty. There appears to be an emerging consensus that the bird was most likely a Common Tern (
S. hirundo) with an unusually pale hindcrown. Several respondents suggested it might be a Whiskered Tern (C. leucopterus), but the bill seems too large, the carpal bar too prominent, the wing coverts between the carpal bar and secondaries too contrastingly white, and the outer web of the outermost rectrix too dark. Other candidate species suggested include Gull-billed Tern (S. nilotica; bill too thin, legs wrong colour), Sandwich Tern (S. sandvicensis; shape and leg colour wrong), Roseate Tern (S. dougallii; carpal bar too prominent and outer web of outermost rectrix too dark), Forster's Tern (S. forsteri; carpal bar too prominent and outer web of outermost rectrix too dark) and White-winged Tern (C. leucopterus; bill too large).