That is predator damage in my opinion and your friend may be mistaken about what can get in.. pictures of the set up and surrounding area along with a location and perceived time can tell a thousand stories.. Even rats eat chicken. That's not the typical look of cannibalism. But I've had a duck scalped by raccoon reaching in look VERY similar to that. Half inch hardware cloth covers all opening now. Look at sofit vents as entry points and so on.
Mites or worms?! How much does your friend check on their chickens?
I presumed the injury to be AS IS and not altered by a knife when I suggested I don't THINK cannibalism to be the culprit.
Not a broiler.. that's almost to stupid to go looking for water and could die of thirst.. I watched my chickens get startled by a rat coming to feed in broad daylight. Try not to presume to many things just because you haven't seen it. Many things depend on hormones kicking in and learned behaviors.. some place rats don't show up until the broilers do.. They (chickens) don't automatically know to eat what they've never seen and doesn't run away like prey but approaches with confidence like a predator.. they usually observe.. rats.. are vicious and will fight back even to my barn cats.. so basically, with all due respect.. you can think what you want.. that doesn't make it true. But an open mind allows for insight!
A possibility but I think it would have been bad a day earlier.
