The player is supplied with 5 Boomerang Birds.
It's hard to use Boomerang Bird and the fortress is quite hard to ruin.
3 Star Strategy
Shoot the first bird right in front of the first Large Pig, causing it, and the 4 small pigs to its left and bottom are killed. Shoot the next bird in a similar style at the second Large Pig. Since the second attack hits a larger portion of the structure, a third bird is usually needed. Shoot the fourth bird so it hits below the glass portion of the structure. The final unused bird awards the player 10,000 extra points.