Thursday, 15 September 2016

More from the white-winged black tern at High Rid reservoir

A few better photos of the white-winged black tern from High Rid reservoir today. The bird performed really well, flying within a few feet at times, but it was quite difficult to follow in my camera due to its erratic flight and the light was so bright that most photos were burned out or silhouetted. Still, shouldn't complain, it's a cracking bird!

This photo shows the shoulder patch very well. Prior to this bird I used to think that a shoulder patch was diagnostic of juvenile black tern, but apparently it's not uncommon for white-winged black to also show this feature (British Birds 82: 296-319 July 1989). As you can see, the shoulder patch on this bird is small and clearly brown, whereas on juvenile black tern it would be larger and much darker brown or black. The bill is correct for white-winged black tern but wrong for black tern, which would have a longer and more pointed bill.

A nice shot of the white rump and pale wings contrasting nicely with the dark "saddle" with scapulars only faintly fringed pale. On juvenile black tern the rump would be grey, the wings darker, less contrast with the back and the scapulars would be fringed paler.

It was often harrassed by the black-headed gulls, especially if it landed on its favoured bouy, and it was very vocal in its defence. I don't really know why it keeps landing on the orange bouy, there are others elsewhere away from the gulls and closer to where it spends most of its time feeding, but it never seems to bother with these. I've not seen it land anywhere else.

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