Very nice exposure control and light. Your angle was not ideal, if you would have moved further to the left you might have been able to see both wings. You could crop some off the top.
I'm viewing this on my old CRT at work and the whites look to be blown in some areas, although it could be my monitor as well.
If the subjects head were positioned so that it was looking at least parallel or toward you a bit, I think that would have made a much better presentation.
I would have allowed for a bit more room at the bottom personally, but that's just to my eyes :)
I like that you captured some action with the wings open. The exposure and whites look good to me. As mentioned the head turned away is a negative, and it's a little tight on the bottom.
A good effort here. I agree with the notes above and would add that if you could have gotten a bit lower it may have made for a more intimate portrait.
Welcome, Geurt
There have been some good suggestions made. I do like the composition and you really were very close to having the right angles,etc. I've seen very few birds posted from S Africa. Very interesting to know what's there so I'll be watching for more posts.