Launch your first shot with a really wide angle into the planet. You want it to circle around the planet and take out the pigs that are located on top of the rocks.
Power Activation Point
Activate your power when you have a clear shot to kill the pig as shown in the picture.
First Shot Result
After this launch, you should be able to kill the majority of the pigs in this stage.
Use the big bird as a final pick up to take out any surviving pigs. You will then make yourself a three star master.
Second Shot Result