Louis, I know that spot :wink:
That is pretty cool, the first time I have seen the Little Green Heron along with the GBH.
I always shoot everything in AF-C. One thing that I find that helps is to not have focus occur with a half-press of the shutter button, but only via the button on the back of the camera. This was a recommendation from Ron Reznick in a class a long time ago, and it serves me well. The other nice thing about this is that you don't accidentaly have issues with the AF trying to "take over" if you have manually focused on something. This may help, I can show you this next time we meet. Also, could you be having issues with VR on the tripod? I am not particularly VR savvy yet, but isn't the 80-400 one of the lense you have to turn VR off when using a tripod?