Hardcore Harry Potter fans will go to great extremes to show their devotion to their favorite characters–and to the world Harry and his friends live in–with everything from tattoos to costumes to…pet ownership?

That’s exactly what’s causing some problems around the U.K., according to The Mirror. When the books and films were at their peak of success, fans everywhere decided they wanted a cute little owl of their own, just like Harry’s loyal companion, Hedwig. The problem is, owls are very hard–and expensive–to take care of unless you have a proper place to house them. Now that the final installment of the movies has been released and the mania surrounding it has died down, people are realizing how much work it takes to care for a winged animal and are releasing them into the wilds of Britain, where they are creating havoc.

Besides the messes owls can make with feathers and droppings, the newcomers are also taking over territories previously inhabited by smaller animals, and some are starving to death in their new homes.

Pam Toothill, who works with an owl sanctuary in North Wales, says she had just six owls in her care before the movies were released; now she has 100.

“Owls need enough space to be able to flap their wings five times before landing back on a perch, or they get a chest ­infection. But we had one lady who was keeping two owls in her bedside cabinet in her ­bedroom. And there was a chap with a ­European Eagle Owl, which has a 5ft wingspan, in his one-­bedroom flat. It’s insane,” she said.

While it’s not illegal to keep an owl for a pet in the U.K., it is illegal to release one into the wild, and carries a steep fine for the owner.

Author J.K. Rowling has acknowledged the problem and is urging fans to use their Muggle heads when it comes to pet ownership.

“If anybody has been influenced by my books to think an owl would be happiest shut in a small cage and kept in a house, I would like to take this opportunity to say as forcefully as I can, ‘you are wrong’,” she said.