Bleeding hen.....any ideas how?

[2emma2]

Hen is an enclosure completely enclosed. No holes anywhere in the fencing and no holes in the ground. She is the only hen in the enclosure. Today she has missing feather on the top/side of head but the skin is not read. Right around the sideof her head close to where the neck starts she is bleeding. How could this have happened? Can her feet reach her head? Could a mite make her bleed like this?

 

[Young Heritage]

Do you have a roo with her? If so he could have done the damage while trying to hold her down.

 

[2emma2]

No, she has been the only chicken in there for a few days and there is no sign of another animal entering the coop.