The following flying creatures must be found for the Room of Rewards.

Seagulls can be found at the boathouse.

Crows are at the Stone Circle.

Pixies are in a desk in the Defense Against the Dark Arts room.

Doves are at the bridge at the Viaduct.

Bats are below the Stone Bridge. Go to the Stone Bridge and light all the torches with Incendio. Then, climb down the pipe shown and maneuver your way to the bottom. You will discover the bats.