My pigeons & chickens share a run & everyone gets along. I had a large coop w/a secure, roofed run, and built lofts on the far end. The pigeons have a high shelves for their food & bath. I asked the same question you posed when I started the project, and most pigeon people thought it was ill advised, as chickens are predatory. A couple things that I think makes my set up work are: I got Silkie chickens, which were not my first choice (not great layers), but they cannot fly & have a wonderfully gentle demeanor, thus pigeons can always get away; I do not breed the pigeons in my coop/loft. If a squab were to end up on the ground it would be killed. The pigeon are very messy eaters & the chickens hang around under their feeding shelf & clean up after them. It might also have helped that the pigeons were settled in first; the chickens grew up w/pigeons in their territory.