Thanks all. I shot these at my neighbors house. They have several feeders in their yard and gangs of 20 or more birds will show up at one time and buzz around everywhere. You'd be surprised how much noise these little tiny birds can make.
As for focal length, I tried to be a 300mm whenever possible. I would watch with the lens at 70 and once I spied a bird I could bring it to 300mm and start shooting.
For shutter speeds, they ranged from 1/650 all the way up to 1/8000. I had the camera at f-1600 in the morning and as more light came on the bushes I lowered to 1250 and then 800. Any slower and you'll end up with a blur where the wings should be.