IS IT OR IS IT NOT MALTING

i have 8 hens which are about twelve months old,they have a run of about 20m square, and night time they have accomodations by means of a 8'x 6' shed,i feed them on layer's pellets and the odd greens,
for quite a while now they have been loosing their feather's, and i mean round the buttocks kneck and back,infact they look ready for the pot.
i have noticed that one of them is also bleeding on the  top area of the tail,
i have picked two birds up to examine, but on inspection i cannot see anythink,like mite or other bugs,i have also noticed the odd bird peck the one that is bleeding,does this one require isolating ? i would be grateful for your comments. cheer's  :?

cheer's foxy i will look into that advice,is your chicks bald round the kneck line aswell :o