|The essential Dutch Birding paper is also available as a PDF on the Birding Frontiers memory stick.|
I mentioned that Martin was lead author on the essential ID paper for this Nearctic tern that was published in Dutch Birding back in 2007, and should add that in addition obtaining the back issue of that journal, the same paper is also available as one of 25 articles on the excellent value Birding Frontiers memory stick (order for just £11 including p&p here). You'll need Acrobat Reader (download free) to view the material, which includes a superb plate of Cabot's (aka American Sandwich) and Sandwich Terns by Ian Lewington.
|Apparent Cayenne Tern Sterna acuflavida eurygnatha (Cemlyn Bay, Anglesey, 8 June 2006). Note the dull orange-yellow tone to the bill, the same colour also being visible on the knees and feet.|
|Apparent Cayenne Tern Sterna acuflavida eurygnatha (Cemlyn Bay, Anglesey, 8 June 2006). From this angle the bill appears more strongly yellow. In some Cayennes, the upperparts can apparently be slightly darker grey.|
Feedback on this or the current status of any claim for Cayenne Tern with the BOURC would be welcome - as a potential split in its own right, eurygnatha has the potential - if the record is accepted - to become a new British bird. In the meantime, thanks to Tristan Reid for allowing me to use his informative images.
Thanks to Ed Smith for drawing my attention to an image from Venezuela of a Cayenne Tern which, like the Cemlyn Bay bird, has similarly yellow areas on the legs - perhaps this is more a feature of this form than illustrations have hitherto suggested. There has also been recent discussion on ID-Frontiers of the identity of a Sandwich-type Tern photographed in Chicago, Illinois, USA, in September 2010 - Greg Neise makes a reasonably strong case for this bird being a European sandvicensis rather than a North America acuflavida (see here), but I guess that's one the committees will be wrangling over for some time.
* NB Watch out for a review of the Birding Frontiers memory stick in a forthcoming issue of Birdwatch.
- Olsen, K M, and Larsson, H. 1995. Terns of Europe and North America. Christopher Helm, London.
- Shealer, D. 1999. Sandwich Tern (Thalasseus sandvicensis), The Birds of North America Online (A Poole, Ed.). Cornell Lab of Ornithology, Ithaca. Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/405 doi:10.2173/bna.405