Friday, 21 January 2011

Angel wings

I put the wrong yeast in the bread-machine the other day. Well, I'll take the loaf to Duddingston Loch after the school run as a treat for the ducks. "Don't kill one with that thing", I was advised. Fair enough since the loaf was like a brick.

The Canada Geese at the Loch seemed particularly appreciative and given that it has been a tough winter I didn't mind feeding these friendly brutes rather than saving morsels for other birds. A little too close for the lens perhaps, but I still get a kick from getting views of any birds like this.

Even feral geese...

One of the Canada Geese kept a little further away. It was suffering from angel wings - a distinctive developmental problem where one, or in this case, both wings are twisted and protrude from the bird sideways. I felt a little sorry for this one, but it did not seem to be particularly interested in my offerings. Nevertheless, look on the bright side, I thought, the condition provides a good view of the black tail, white uppertail coverts and black rump which are normally concealed from view...

It turns out that, while this developmental condition is not well understood, it is not necessarily thought to be genetic. Instead, it is hypothesised that it is a condition brought about by an inappropriate diet - a diet excessively rich in protein. Angel wings occurs in populations of wildfowl that are fed by humans and it is suggested that excess protein in the food provided by humans causes excessively fast wing feather growth in young birds. This increased feather bulk and mass causes the young developing wing-tip to twist at the carpo-metacarpal joint and the wing then develops in an inappropriate position.

Looks like this bird was right not to take my bread after all.

No comments: