Working on article on the subject right now
(BTW, does anyone out there have any decently-focussed photos of rabbits+chickens that they'd be willing to let me use? I =need= to find something to illustrate the article and am becoming desperate. Will consider paying for it, although let's please remember I myself am not being paid much for this -- and definitely I would send you a copy of the magazine when it comes out. Doesn't ANYONE want to see their bunnies and chickens [together in same photo] in print? Please please please???? PM me!)
Anyhow: Coccidia are NOT a concern, straight from the mouth of a U of Guelph parasitologist who specializes in coccidia. They are almost totally species-specific, and rabbits cannot be infected with chicken cocci or vice versa.
Biggest health concern would be salmonella; to a much lesser extent, pasteurella, listeriosis and e coli. I would not personally consider putting rabbits in with chickens that have had a salmonella problem (paratyphoid) in the past as they can remain carriers. The others mainly cause clinical disease in rabbits when the rabbits are already stressed by poor diet, cold, heat, social stress, etc or if everybody is just plain wallowing in feces from poor sanitation. Plenty of people do seem to mix rabbits and chickens without problems, mainly by keeping everything clean and everyone healthy to begin with. Putting hutch (raised above floor) in coop, or letting the buns and chickens live separately but share an exercise yard, is probably safer than living together 100% of the time if you are worried.
Word is to use straw NOT shavings if rabbits can get into coop w/chickens; and make sure they can't be eatin' at each others' foods. Chickens eating lots of rabbit food = malnutrition and poor laying; rabbits eating lots of chicken food = likelihood of serious, possibly fatal, intestinal or urinary-tract disease.
Disclaimer: I do not have rabbits myself, this is all info scavenged from others
Seriously, I am REALLY REALLY looking for photos, can anyone help?
Pat