Wednesday, 2 February 2011

Northern Fulmar plumage variation

For fear of getting doused in foul-smelling vomit, I didn't fancy getting too close to this young Northern Fulmar on North Ronaldsay, Orkney, in August 2009. As is often the case with the less-appealing types of baby birds, they do tend to mature into beautiful adult birds.

Here are a series of adults photographed from Burness on Sanday a few days before. These birds are all of the typical double-light plumage morph, but I have organised them from darkest to palest. From these pictures it looks as though feather wear may be responsible for at least part of this variation.

Last September I was lucky enough to have an opportunity to snatch some photographs of a 'blue' morph Northern Fulmar while on a pelagic trip off Newcastle (this bird is probably best considered a light morph or intermediate morph; the terminology is confusing in a UK context because blue fulmars are darker than our normal double-light birds but are still considered light in comparison with darker northern birds). This is the best shot, and as you can see it is not the clearest. I really wish that I had asked for the boat to turn to get a second look at this bird, but at the time thought that no-one else was likely to be that interested. Also, I was slightly skeptical that it was a 'real one', but have since found out that there appear to be a small number of resident birds in the North East of this plumage morph. Oh well, I'll get better shots, and, more importantly a better look, next time.

Nice bird? Well, it looked pretty neat in real life, and had quite a grey-blue hue to its head, neck and flanks, and in flight it looked really good, but it is not as dark as more northerly blue fulmars (dark and double-dark morph birds). Note the much heavier marking across the bill, which is typical in the blue fulmar. I managed to pick up another blue fulmar (light/intermediate morph) while seawatching off Buness, Fair Isle, in October and am now quite a fan of them. I must remember to have a look out for one off Lothian over the next few weeks.

On the same pelagic trip there was significant variation in the appearance of the regular morph birds. In the next shot, the rear bird has heavily abraded or moulting coverts (maybe a sign of a failed breeder moulting early) and a yellowish tone to the white head and body feathers, which is quite common.

The bird in the foreground seemed substantially paler in the field and I think the whiteness of its head, body and tail is quite striking. This bird may be similar to the palest bird in the flight shots above. I wonder how different these birds would be to the triple-light morph, which may or may not exist. On the other hand, I think it is possible that they have abraded tail feathers that appear whiter than normal. Anyone know?

Finally, here is another bird with quite serious primary moult. According to BWP, primary moult occurs in rapid succession but growth of outer primaries is slow. That, I think, hits the nail on the head - only a couple more primaries to lose on that left wing, but the new ones have got some catching up to do...

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