This stage is tricky because you have to follow this exact setup to get the 3 star mastery. Enter the planet at the angle shown.
Power Activation Point
Use your sword power to break the wooden block from the “first” cage. You will have to use your bird to crash into the second one. This is because the rocks from the first need to drop first. Then the second set can drop on them to get you additional points.
Without the setup and extra points, you will not be able to obtain the three stars in this stage.
First Shot Result
The stones drop and crushing the pigs on the right side of the planet. Your bird continues and take out the bird on the top left. The bottom left pig is also killed by moving blocks caused by the metal balls shortly. You will then obtain your three star mastery.