As compared to all the other event buildings you cannot place an EE spell on the owl. I guess it's a new building and the devs forgot to place in the "EE-possible" buildings. Nothing urgent.
Hm, now that you mentioned that I noticed that you cannot place an EE spell on the Fire Phoenix (that also requires pet food) as well. So you cannot place EE spells on event buildings that require pet food. I don't understand why (they could get pet food for the extra effect and EE for the extra culture) but ok. Now I know it.
Thank you for the quick reply.
you cannot place EEs on any Pets.
The devs couldn´t figure out how to program two different enchantments on the same building (at least not in the time they were given by Inno)