Ah, clever. It didn't quite click in Aedan's mind until he was already after her that she might have had an ulterior motive behind the swimming. Not that he minded, made the chase more interesting.
When he lost track of her, he instinctively shifted into his bird form, flying up to get a better view over the trees. He wasn't really in the right state of mind to attempt climbing them as a human. Maybe that was cheating, but... did it really matter? If you didn't set down rules when you told a mage to catch you, it wasn't like they could be broken.