That's a tough decision. I usually error on the side of caution and do a slow integration for about 3 weeks. But if you aren't planning on keeping him, you may not want to introduce him. My hens stopped laying for a little bit when first introducing a new member and after my rooster needed to be...
Great idea to keep the mystery chicken separate from your other chickens. I look forward to some pictures in the morning.
I get a lot of rooster dropped off in my woods but the farmer across the field loves taking in these roosters to join his large flock. I hope you are able to keep him if it...