Aim straight in between the two planet spheres. You will need to really aim right in between for this stage to work.
Power Activation Point
Activate the power at the location shown in the picture. The timing is extremely important because you need the split birds to go through the ice blocks at a correct angle.
First Shot Result
The birds fly through the ice blocks, knocking them down and killing all the pigs. You will then have enough points to guarantee you the three star mastery.