HELP! My hen is picking her own feathers!

[Farm Chic]

My hen is about 6 months old and she has been picking her own feathers! She is a polish hen and most of her tail feathers and around her tail area have been plucked right down to the skin! Any ideas as to why she may be doing this??

 

[katrinag]

Have you seen her do this? Have you check for mites/lice?

 

[Farm Chic]

my hubby has seen her do this and he said that he didn't notice any mites or lice. we have 20 birds, if one has mites/lice, wouldn't more than one have it?