Yowling and wandering cat advise!!

I recently (as of Monday) took in a male black cat that was a stray we had been feeding for about 2 months. Took him to the vet on Monday and he was fixed that day. It is now Friday and EVERY night it's the same thing: wanders the house, yowling. I refuse to let him back outside and back in the house where my 5 other cats are. My vet told me it would take at least 30 days for all the testosterone to clear his system. But when it does, will this behavior stop?? It has been keeping me up all night long! I read somewhere that if the wandering behavior is something he has done pretty much his whole kitty life (thus far) it more then likely will continue. Ugh, really hoping it's not ture!
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Anyone have any answera or advise? Greatly appreciated!!

Hi and welcome to the cat site!

Male hormones once fixed take about 20 days to adjust. The pee will no longer smell so strong, and he will settle down.

You said that you won't allow him back in the house with your other cats, but won't allow him back outside, so where is he staying?

Thankfully he has not sprayed in the house. He is staying in the house with the other cats. I just don't want him going back outside and having to keep flea treating him every month (we get ours from the vet and its a bit pricey). Its just the yowling won't stop!

Much of the yowling is stress related.

New house, new family, new smells, sights, sounds, and other residents pets.

He will adjust, really he will.

I know too well how annoying and frustrating the yowling is. 

Is he bonding with you or anyone in particular? If so, can he be in the room with that person during the night?

Given time and lots of patience, he will settle down.

Not only his hormones but in general, his disposition.

It's just like rehoming an outdoor cat. It must be contained and acclimated for a full month for him to be released and stay where he is.

First week he is not taking in anything about his new surroundings, he has a mindset of resisting his new place and can only think about getting back to where he was living.

Week 2 is a bit quieter, as he becomes hopeless that he will be going back, as the end of the second week approaches, he will start becoming more in tune to his new home.

By week 3 his memory of his old home is beginning to fade, and he continues to take in the new place, smells, sounds, sights, etc.

Week 4 he is accepting that this will be okay, this must be where he will live,  he feels safe and is fed and cared for.

Very similar to your boy and his thinking.

Actually he has bonded very well to me and my boyfriend. We did try keeping him in the room with the door shut at night his first 2 nights home, and all he did was cry. Now we let him wander the house as he pleases (still hissing at the other cats but we watch him) and it has helped a little bit but still yowling. Maybe he does want back outside cause that what he is used to, but he doesn't really seem to be resisting living here. 2 days before we took him in he was sleeping behind our garage in a pile of leafs and now he sleeps anywhere he wishes and loves to cuddle. Just hoping he quiets down soon, currently 32 weeks pregnant and have barely slept for the past nights and when the baby comes (if we still have him, our main Gail is to re home) he won't wake the baby with his yowling.

Well either way, if he is rehomed or not, in a short amt of time he will def. be settling down.

Many of us here are so grateful for caring people like you, you have changed his life forever, taking him in, having him fixed which is huge, will have a great impact on his future

I wonder if you'd have any luck with feliway?

Not sure. The yowling has thankfully stopped. Bow it is his aggression towards the others.

He needs to settle down. The whole situation is a totally new experience for him. He is used to running outside, getting food irregularly (except when you were feeding him), being cold and switching places often. Now he is indoors with new people and new cats and everything is different. He needs some time to understand those cats are his friends not enemies just like you. If they don't bother him and just let him be you will see everything improves soon.