Well i usually setup my camera, plan the shot, then when the birdys arrive it take a burst of about 20-30 shots in space of 10 seconds.
This was shot on Manual Auto Focus (As i call it). I basically set the lens on autofocus then i can then tweak manually once locked on focus (My lens allows me too) and since its a Sigma HSM lens its fast glass.
Shots taken on F2.8 - 640 iso (Usually ill work on 200-400 iso but it wasnt a particually sunny day was quite dull)
Also for the second shot, the trick was metering my exposure on the foliage behind the birds. Luckily the foreground was in the shade so they was in a lot darker environment to the background creating the shot you see