My hen, Alejandro, liked to pick at ANYTHING the slightest bit abnormal. Whenever I went outside to sit with her, she'd clamber into my lap then start looking for ways to draw blood (or so it seemed). She would try to pry off fingernails and toenails, nip freckles and moles, and boy did she get excited if she found a scab that wasn't covered! She'd tear it off and eat it before you had time to react. You also had to be mindful of any loose buttons - I had to wrestle them out of her beak a few times to prevent her from eating them.