Here is our guide to get 3 stars on Poached Eggs Level 1-21.
1. Aim the bird at the leftmost portion of the structure.
2. Aim the next bird at the middle part of the structure.
3. Aim the third bird at the wooden base of the middle structure.
4. Weaken the rightmost structure by aiming the blue bird, and then the red bird at it.
5. Aim the yellow bird at the remaining debris.