Here is the full list of all 11 Songbird Symphony achievements.
Played your first song.
Have Egbert join Birb in his adventure.
Found the Songbirds' Memorial.
Gained entrance to the party.
Discovered Birb's identity.
Saved the forest.
Identified all birds and their feathers.
Found all the world notes.
Helped Egbert hatch.
Listened to Poot's plans for revenge.
Found the secret area with the developers.