Thanks for that information. The only way I’d be able to quarantine him is to let him in my property out of the girl’s area to roam, no coop etc. he will not let me approach yet, maybe I’ll gain his trust. As far as asking neighbors, most people are completely fenced in so you cannot get to their home, like me. I’d hope no one abandoned him but there are cruel people

Maybe he will go home to roost tonight and if he’s back tomorrow I’ll have to make a decision. He’s gorgeous though.
If you have predators, he can't be left outside. He might roost near your hens though, and you might be able to catch him that way. Do you have a dog cage that you could set up in a garage or basement? That could be a place to keep him until his quarantine is over.
Personally (
this is bad advice I'm giving here and can be very dangerous), if this was me, I'd check him over for mites and if he passed the test, I'd throw him right in with my birds. I might quarantine him for a few days, but in a time that's too soon I'd throw him in with them. Yes, this is terrible advice and because you're not me, I don't think that you should do that
at all. The only reason why I'd be so trusting that he doesn't have anything because of the situation. He's young and abandoned. His previous owner most likely got him in the Spring, didn't know too much about chickens and this probably was their first batch, and when it was too obvious that he was a rooster, they made the (bad) decision to get rid of him. I've seen this plenty of times before, and the person's inexperience is the only thing that guarantees no disease. They get their chicks at
TSC and don't add any from anywhere else, thus unknowingly protecting their flock against disease.
Again, I've just given you terrible advice. I've rescued several roosters who were abandoned, as well as a flock of hens who were all of a similar case. I had no issues with these rescues, which many did land immediately in with my flock due to me trusting the inexperience of the person who abandoned them, except for one case. (And one is all it takes.)
There were three roosters wandering around my property, trying to get to the hens, and I was able to catch two of them. I
did quarantine these roosters, but unfortunately, I didn't recognize something I was seeing on one of the roosters as something to be worried about, so I threw them in with my girls once quarantine was over, thus introducing MG to my flock. With a whole flock infected, and still not knowing what MG even was, I dealt with it in my flock until I decided to stop chickens for a season and later learned about it here on BYC. I had no clue, risked my flock, and they lived with the consequences of that action. Since hand, I have played with that risk yet again, but then again, it's a risk and shouldn't be taken.