All my birds love cherries (even the canaries get a half each) and, as they are in good price right now (they need to be organic), they have been getting them, at least, once a week. And they get them whole, too! I've never had a problem with any of them swallowing the pits. The only thing you need to do is remember that you fed him cherries because you are going to find scary black poop after and, if you are like me, you will panic BIG TIME if you don't
And try giving him blueberries, July is the best month for them, they are highly nutritious and my zons LOVE them! (Bad poop alert for them as well as blackberries, another favorite of them).