Proposal (#25) to South American Classification Committee

 

Add Morus capensis (Cape Gannet) to main list

 

Manuel Plenge pointed out to me the recent publication of a photograph of Sula/Morus capensis in the paper that I circulated to all of you as a pdf file:

García-Godos, I. 2002. First record of the Cape Gannet Morus capensis for Peru and the Pacific Ocean. Marine Ornithology 30: 50.

 

We have this species on the Hypothetical List based on sight records from Brazil and Argentina (the latter possibly also a photo -- Alvaro is checking).

 

What I know about gannet identification was learned only moments ago. I think I see enough in the head and throat in the photo to exclude the similarly plumaged adult Masked Booby (Sula dactylatra), and the brief description notes presence of long gular patch and yellow wash on head. The black secondaries and rectrices, clearly visible in photo, eliminate N. Gannet (Morus bassanus). The key characters for distinguishing M. capensis from M. serrator are reduced black in rectrices and shorter gular stripe in latter. I cannot discern the length of the gular stripe from the photo. However, it is clear that the outer rectrices are black; if this is indeed diagnostic for capensis, as is widely reported in standard literature, then it "has to be" capensis. If anyone has information to the contrary, please speak up. With the caveat that I do not know these birds in detail, it seems safe to conclude that by conventional standards the photo does document the species for South America (and first for Pacific Ocean).

 

Van Remsen, 3 March 2003

 

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Comments from Jaramillo:

"I looked into it a bit, and indeed it’s a match for capensis. I also sent it to Ned Brinkley who has a great deal of experience with Gannets, including oddly plumaged adults observed in North America which have shown features suggesting other gannet species. He felt that the photo was of a classic capensis, with the gular stripe being a clincher. I vote YES to accept this species to the main list. I also apologize that I have yet to lay my hands on the photo that I recall of the Argentine record which was in El Hornero, a journal that is not all that easy to get around here. Even more difficult to get when the year one is looking for is out being bound!

 

Comments from Schulenberg: "I don't know a lot about Sula capensis, but based on what I do know, this photograph seems to be identified correctly. I assume that Sula serrator always has white outer rectrices, otherwise the identification would become more problematic. So I vote "yes". I seem to recall, a number of years ago, a report in British Birds on the first occurrence in the United Kingdom (and in all of the Western Palearctic?) of a vagrant from North America. The bird was photographed, and there was no question of the identification (Bay-breasted Warbler, if I remember correctly, which I may not). However, there was only a single observer of this bird. So the British records committee went to some trouble to have the plants that were visible in the photograph identified to species, in order to confirm that the photographs indeed were taken on the correct (eastern) shore of the Atlantic Ocean. At the time I thought, "Oh, those Brits. What a silly people, never missing an opportunity to be pedantic little poops". But now, even though I am voting to accept the record, I admit that I'd feel better about my actions if there were something visible in the photograph that would help confirm that the photograph came from Peru."