The polecat is well composed but I believe it is a captive (British Wildlife Centre) animal. I know that many wildlife photographers enjoy this sort of photography but I believe it should be made clear that the subject is captive, particularly if it would be difficult to photograph in the wild.
The Avocets pic is stunning. I note it's going to be included in the AA book featuring entries in the 2011 British Wildlife Photography Awards competition which will be available from 30/9/11. Pretty amazing for a photo taken on 27/9/11.