HELP!! What can i do to treat and prevent chicks from pecking their tails off !!!!

[alejandro209]

my chicks are starting to change feathers and others are pecking the tail feathers off and unfortunately I had one that died because of the constant attacks and it was to late when I noticed and i had to separate two that are in the same proses but i have 15 and not enough cages to separate each one that is starting to change feathers please help ASAP