Proposal (509) to South
Transfer Chlidonias leucopterus from Hypothetical List to Main List
Effect on the SACC List: This transfers a species from the Hypothetical List to the Main List.
Background: The Hypothetical List currently reads:
Chlidonias leucopterus White-winged Tern: Published photo from Rio Grande do Sul, Brazil (Aldabe et al. 2010).
Aldabe et al.’s abstract reads: “On 20 November 2008 a single White-winged Black Tern Chlidonias leucopterus in complete breeding (alternate) plumage was recorded in Lagoa do Peixe National Park, Rio Grande do Sul, southern Brazil. The bird was photographed showing the diagnostic black underwing coverts. It is suspected that it was an occasional visitor. This is the first record for Brazil and South America.”
Photographic evidence: Two photographs are reproduced in the publication (just email Van Remsen if you need a pdf). They clearly show the diagnostic pure white upperwing-coverts, diagnostic white rump contrasting with a black head, throat, and breast, together with diagnostic black underwing-coverts.
Recommendation: There can be no doubt about the identification, there seems to be no controversy over the authenticity of the locality data. The only anomaly is that the first author did not see the bird. I recommend a YES vote to add this species to the main list as a vagrant to the region.
Aldabe, J., Rocchi, A. & Mondón, G. 2010. Primer registro de Chlidonias leucopterus (Charadriiformes: Sternidae) para Brasil y Sudamérica. Rev. Bras. Orn. 18(3): 261-262.
Mark Pearman, October 2011
Comments from Pacheco: “YES. O CBRO acompanhou com interesse a divulgação e confirma as qualidades do registro.”
Comments from Pérez: “YES. Evidence is clear and is supported by the Brazilian Ornithological Records Committee, as stated by Fernando.”
Comments from Jaramillo: “YES. Looked at the photo and it appears undeniably to be that of C. leucopterus. This one was overdue for South America as well!”
Comments from Zimmer: “YES. The published photograph from Lagoa do Peixe leaves no doubt as to the identification, and this is a likely locale for such a bird to turn up.”