How did he know Mulgarath would turn into a bird?
-Spoilers-
At the end when the kid throws the book off of the house, how did he know the ogre would shape shift into a bird? I mean he could have stayed the same ( A thing that size could withstand the fall, plus he's magic) or he could have morphed into another animal that Hogsqueal couldn't eat. Then they'd be totally screwed.
Did he have preset shapes to shift into ( Like a werewolf can only be a man or wolf) or was it just a case of fridge logic, its a kids film so it'd have to work?