Well I never keep strays in isolation, if you take your birds to race, I bet someones birds are carrying some thing. You better be sure of your own birds health. Birds come to me and I feed and water with mine, however I then chuck 'em out. An Irish stray I had came in, every day for two weeks, but he didn't stay in the pen, infact he left the pen every time I went near. I only knew he was Irish after the wind turned east and he made a try for home, he came back coverd in blood and well bashed up. I got him well and when the wind changed again he went back home. I love pigeons and I love that stray...............!!!!!!!!!!!!!!!!!! Treat them as you wish others would treat yours.