Upon googling "can I feed cherries to chickens" I got the answer, yes, the chickens will eat the cherry part and discard the pit. Well, I have nan-king cherries (very small pits) and after feeding the flock of 3 month old EEs these cherries, I didn't see as many pits as I expected. I watched as a cockerel ate a cherry and swallowed it, no pit expelling going on. Now, a human eating a cherry pit is no big deal, it goes right through. A chicken, however, uses a gizzard to grind up that which it eats. I gotta believe the chickens are getting the full dose of cherry pit cyanide when they consume a cherry pit.
None of those chickens have died so far, so obviously the cyanide did not reach the level required to kill a chicken. I do wonder, however, whether the cyanide collects in a chicken heart or liver and would be potentially dangerous to butcher shortly after eating cherry pits. I have read that cyanide does not accumulate in a body like mercury does, so I gotta believe the danger (if there ever is any) passes rather quickly.
The net, I no longer plan to feed the chickens Nan-king cherries. Whether I can keep them away from the tree in the spring when cherries fall off, that's another question.