Awwwe. I have seen worse however. Do you have any sort of "toys" or amusements for the other birds to investigate? Some hanging CDs , tennis balls, Orange halves, even a few water-color-painted wood blocks. Chickens can get bored and start to "pick" on one or more birds in the flock. I have also seen this behavior when there is not enough perching space for all the birds to use at night. Too many roosters in the flock can also get them riled up.