My wife just witnessed a battle between one of our girls and a big fella called Tazzy from a couple of doors down through the catflap. I caught him near the backdoor the other day today and spotted him when the girls have been bouffed. I think we have our culprit.
What can I do about it? Could look into getting a chipped flap that would stop him getting in (if I can find one that would fit) but they like to fly in through the flap when being chased and they might smash their faces in/not get in in time.
I can keep chasing him off but he is pretty bold.