I had another go at the Great Crested Grebe today and got some shots of its mating dance. Quite a performer (I posted a few others on the 1DX thread, http://www.canonrumors.com/forum/index.php?topic=8079.2595
600mm f4L IS II, 1.4xIII extender
1/1000s, f13, ISO800
Great shots of very cool birds, Location ?