Thanks people, its really nice to chat with people who appreciate pics like these. They take a bit of effort and patience, as well as just watching and understanding how the animals are behaving. Most of the shots are cropped of course, some not that much though as the 500 really does have some reach and the birds get used to you if you just stand still and act like a tree
I'd love to get the 200-400F4 +1.4X, am going to wait to see how the price holds and what other things Canon release, including the much rumoured 100-400 replacement (which was sold to part fund purchase of a very crispy newish 300F2.8 secondhand). The 200-400 is still very hard to get anyway.
On Flickr I'm steve.mack