My sister has chickens and they are mean. I think they will peck at a tort. They peck at each other. Plus I would be concerned about the chicken poop around the tort.
My chickens don't bother my torts, but they do make a big mess everywhere. They try to eat the tortoise food and they leave little steaming hot piles everywhere. I haven't seen my tortoises try to eat it, but they might have. Now I keep the chickens out of the tortoise area entirely. Thats the safest bet.
I have seen several breeders of multiple species of tortoises have chickens in the same area, I do not like the idea. However, a flock of peacocks fly into our open tortoise fields and never no problems.
I had a sick tort brought to me with ear abscesses, the tort was kept with birds, We did a culture abd the bacteria found was from bird feaces.
Also The Tortoise trust have done their own study on this and have found that alot of infections are from bird fecal matter when the 2 are kept together.
thanks for all the help guys. the desert tortoise has the run of the entire back yard which is all native desert plants and D.G. so I think that chickens are out of the question.