a few questions... but first Welcome to BYC

from the San Diego high desert.
How old are your hens
Hows the temperature in your neck of the woods.
Whats their diet.
When having behavior issues there is also space concerns how much space do they have to be chickens in. In hot climates they will need more than the usual four square feet per bird coop space.
One temporary fix for the picking till you determine the cause is to Paint their feet blue with blue coat... Looks goofy and is a mess to apply but it hides any pink or blood specks that attract pecky beaks. Blue coat can be bought at the feed store and is a thin antibotic ointment applied by a dauber in the cap. Wear rubber gloves if you can and pants that you dont care.
Its good stuff to have on hand any way. even if you never use it again. I keep a bottle in the critter first aid kit.
deb