Darwin (the Great Briton, not the Australian rubbish tip)

I've been thinking about Darwin quite a bit recently. Not sure why. Probably something to do with the fact he's been on telly recently for this "100 Greatest Britons" programme. Anyway, it got me to thinking why survival of the fittest doesn't really seem to apply to birds. Probably not the subject to discuss on a public forum where I'm open to all sorts of accusations. Catch me down the pub and I'll expand on my theories.