I have been trying to develop my skills with wildlife as well and I started out with a 100-400 L---Though this is a great lens and has served me well, I think I am going to go withh the 400L prime. The pictures are clearly sharper with the prime and the prime is a little cheaper than the Zoom. I personally am not a fan of the extenders and only use them as a last resort. If you want to shoot wildlife (outside of a zoo), get as much reach as you can for the buck. My suggestion:


400L, 5.6: $1200.00 (read Bryan's review and look at Nate's bird Photographs)


Use the rest of the money for other things you may need or want, i.e. extender, good tripod, battery grip, memory cards, backpack, or a good walk around or Macro Lens.





Good luck