I've fed chickens/chicks to burms before, and quinea pigs. Actually, my burm went absolutely nuts for chicken. The only problem with chicken is that the stool afterwards tends to be pretty runny because of the feathers. Apparantly, they don't bind the stool like fur does. Also, I personally think chicken is not a good source of calcium, after all, their bones aren't very dense, so there can't be a lot of calcium there. I think you're ok feeding chicken every once in a while, but I wouldn't make it a mainstay of your snake's diet.