1. Collect bird feathers throughout the game. These can be found in various locations, including trees, bushes, and rooftops.
2. Use the bird feathers to craft a bird call. This can be done by combining two bird feathers with a piece of string at a crafting station.
3. Equip the bird call and use it to summon the blackbirds. The blackbirds will fly down and begin to attack the enemies.
4. Use Shrek's or Donkey's attacks to defeat the blackbirds. The blackbirds are relatively weak, so a few hits should be enough to defeat them.
5. Repeat steps 2-4 until all of the blackbirds have been defeated. Once all of the blackbirds have been defeated, you will be able to progress through the game.
Tips for defeating the blackbirds
* Use the bird call in an open area to give yourself plenty of room to maneuver.
* Be careful not to get surrounded by the blackbirds. If you do, use Shrek's or Donkey's crowd-control attacks to clear some space.
* Use the bird call as often as possible to keep the blackbirds coming. This will help you to quickly defeat them all.