
Originally Posted by
Markus Jais
The 4/200-400 VR from Nikon is a great lens and used by many photographers. Particularly with large mammals this lens is fantastic but also with birds if you can get close enough. It will not replace a 4/600 VR.
For birds I would recommend a 4/600 VR or the much lighter 4/500 VR. The 600 VR is heavy (Canon lenses are now much lighter than Nikon super telephoto lenses). Add a 1.4x and you will have a great setup.
For hand holding the 4/500 VR will be much lighter. The 2.8/400 is also heavy. Of course this all depends on your physical strength. I do handhold my Canon 4/600 II (3.9 kg) and can do that for quite a while but still wish it would be even lighter (the Nikon is much heavier).
A good combination would be the 80-400 + the 4/600 VR + 1.4x and a D600 (or D610 once out) and the D7100 due to the crop factor and good AF system.
I am not sure if this really answers your questions but I hope it is helpful. It depends a lot on what you want to photograph and how shy the animals are in your area.
Markus