A couple of Snow Geese seem to be flying in tandem, but in reality are a part of a huge flock of tens of thousands of birds. The white puffy specks in the bokeh are all snow geese.
And yes the autofocus on the Nikon D300 seems very quick and accurate. I would be careful of using the 51 AF Pts w/3d tracking on large flocks of birds, the af may have a hard time deciding on the subject. But if you are going to isolate close birds in a flock with bokeh it seems to be bang on. I'm going to have so much fun learning about all the finer details of this fine camera.