Is this rat damage?

[Humble Shack Farm]

Hi! This morning I found one of my silkie roosters was missing a large patch of feathers on his head/neck and was bloody. I don't know what could have hurt him so badly. It looks like something pulled out a bunch of feathers and broke some others (maybe some new ones too that hadn't fluffed up yet). The back of his neck was red and swollen, and one spot was bleeding.
I'd like to know what could have caused this injury so I can protect the rest of my birds (two large flocks that will be increased in late June with new chicks ). I evaluated whether it might have been caused by a fight, but the other roosters that he lives with are not known for fighting and certainly not for actually injuring each other. Silkies mostly fight by jumping around and up and over each other with their feathers fluffed up (they look like fighting cotton balls, LOL!).
We have had rats in the coop in the past, and though we covered the access points with hardware cloth (and covered the whole ceiling) there are a few areas in need of repair to keep the rats out again so it's possible they are getting in. Last night's temps were below freezing.

 

[ChickenCanoe]

It could also have been a weasel or mink, however they would have likely killed the bird.

 

[Humble Shack Farm]

It appears that the injury may have been caused by some of the other roosters after all (I breed silkies so there are often multiple roosters at times, the older ones keeping the younger in their places). I hadn't seen any aggressive behavior between them, but today when I returned the injured rooster to the flock (after treating his injury and keeping him warm last night) I actually saw two of the younger birds corner him in the coop.
Those two roos are spending the day by themselves, separated from the flock, and they'll get one more chance to assimilate back into their proper places in the pecking order. If that doesn't work out they'll have to find new homes immediately because I can't have them tormenting the other rooster.
The only good things about this discovery is that I actually saw something happen so I can now protect my other rooster, and it doesn't appear that a predator found it's way into the coop.