hi i have 4 rir, 1 slw, 1glw, and 4 bsl. i went out to the brooder to check on them and all the sex links are being picked. they are 3 1/2 weeks old and this is the first sign off picking. i have them in a 150 gallon rubber maid horse trough. i have a clear 250 watt bulb. why are the picking on the sex links only and how do i separate them but not keep them away so when the are healed they wont be accepted back in to the flock. please help they are bloody on there bottoms and also on there right shoulder.