Like you I prefer to work wildlife without the tripod. That is the advantage of my Minolta 7D with it's built in image stabilization. Most times it will give the extra little help I need to get the image without a tripod. But as I get familiar with the Canon 400 f/5.6 it can be hand held if you have good light.
This is an unprocessed (just cropped) RAW test shot from yesterday handheld:
http://www.pbase.com/jhuddle/image/73138205.jpgThis was shot handheld in the field and it worked even though it was a very dark overcast day. Just had to punch up the ISO and shoot a wider aperture than I wanted:
http://www.pbase.com/jhuddle/image/72054501.jpgIn the field I also use whatever I can to steady the gear. Put the lens against a tree, kneel, shooters stance, hold breathe, etc. to get a sharp image.
