[LGS]

Hi - Im new to the forum although i've been reading it for a while.  I have 5 black rocks and 1 light sussex that are all about a year old now.  I've noticed for the last month or so most of them have been going bald on their underneath - from the vent up to the chest (altough the chest is still featherd).  The bald patches are red and look sore.   All other feathers seem fine and all laying and behaving fine. Any ideas of what this could be?

[Roughlee Handled]

Hello and welcome.

Have you checked over for creapy crawlies?
Can you see the feathers on the ground?  Are the other birds eating them?
Do you give your girls supplements ie oyster shell or limestone flower? 
How big is there run / coop.
Can you photo the bald patch as this may help.
Are there any quills coming through?  Black/vien coloured small spikes
Could they be moulting? Every chicken will go through a partial and then one full moult every year.

[Foxy]

Could be a partial moult or maybe lice as Ruf suggests. If it was just one I would be thinking broody but not all of them, and not black rocks.
Where are they roosting at night? Nest boxes or on a perch?

[Debz]

Sorry to hijack your thread but my girls are the same at the moment.  They are warrens (pol August 08).  I have checked them for beasties and can't see any.  They have grit and oyster shell available at all times and they perch at night.  I have assumed that it is a bit of a moult but they are also pecking each other too.  Well two are getting pecked and although the third has bald bits too, she doesn't seem to have any sore bits.  Mine are still laying and seem bright enough which is why i thought moult.

[WhatCameFirst]

Strangely mine are a bit like it too, and definitely no creepy crawlies. They have little bald chests, just about an inch or so of bald patch.  But they do rub themslves :blink:  up against their chicken wire when they see one of us coming with an armload of cauliflower greens from the village shop, so ours could be "pressure baldness"??

[LGS]

Thanks for your replies.  In answer to your questions:

I have checked for crawlies and can't see anything although not sure what I am looking for. 
I can't see any feathers on the ground - I assume this means they are eating them?
They always have oyster shell/grit mix avaliable
Tthe run is about 4 by 2 metres
I will try to photo the patches but it will have to wait til weekend
And finally yes there does seem to be quills coming through but they just don't seem to come to anything
I'm not sure if it is the moult but it does not look like pictures I've seen in books.

Do you think it could be lack of something? - protein maybe?

[Roughlee Handled]

If there are quills coming through then I would say it is most likely to be moulting. 
Can I just point out a 2 by 4 metre run is possibly a little cramped for 6 chickens. The minimum required (and this is the absolute minimum) is 1 metre squared  per chicken and yours have 1.33m. I would normally suggest to people 2m per chicken minimum as this helps reduce behavioural problems like pecking.