What did we all do before the Internet? The speed of communication sometimes just knocks me out. I forwarded the photographs of Sooty Shearwater on to Dr Ismael Galvan at the Department of Evolutionary Ecology, National Museum, Madrid who led the team that produced the original paper, which I'm going to have to purchase now. I enquired if Sooty Shearwater was one of the skins that they examined as supportive evidence and if they thought that the feather mechanism discovered could be present in Sooty Shearwater. this afternoon I had a reply which I'm sure he won't mind me publishing part of. Dr Galvan replied
"Thank you very much for your interest in our work and for sending these amazing pictures. In our paper, we aimed at describing the mechanism because it has been overlooked, but did not try to perform a comprehensive search of sheen feathers among birds. This is because we didn't conduct a comparative study, although this must to be the next step. However, we searched for these feathers in several species of birds from different phylogenetic groups, which led us to conclude that sheen feathers seem to have evolved in large species that are limited to generate conspicuous colouration through other mechanisms. Thus, the Sooty Shearwater fits very well in the group of birds we predict to have sheen feathers. Indeed, and although we didn't examined shearwaters in any museum collection, after viewing your pictures I'm almost sure that the silvery colour they display when in the sun is produced by the same sheen feathers we have described. Sheen feathers are easy to identify because they present a whitish, fuzzy appearance without iridescence. The effect in Sooty Shearwaters is very similar to the effect that can be seen in Bearded and Egyptian Vultures, you can be sure this is the same mechanism. However, I'd like to examine shearwater feathers closely. Do you have flight feathers of Sooty Shearwaters?"
So if anyone out there finds a Sooty and wants to forward on a couple of secondaries just drop me an email at firstname.lastname@example.org