Gasp! Professor was going to call a whole hippogriff herd! That would be interesting and exciting!

Ira thought about the question asked but didn't know the answer. But from others' answers she gathered that the owner must cast spell. So she raised her hand up and answered, "Sir, the owners of hippogriff are required to cast a, umm... a disillusionment charm on it to prevent it being seen by the muggles..."