Odd damage on Ilex x wandoensis from Korea

We were pruning the Hollies on Korean Hill today that were damaged during the snowstorms of February. Branches falling from the tall pine trees onto the understory Hollies snapped off a few trunks. Amanda noticed that they weren't broken high up where the trunks were thin, but mostly within 3-4 feet of the ground. Closer examination revealed these odd patterns, presumably the result of some animal action??. The wood behind was weakened and so that's where the trunks broke. One particularly enterprising Holly had, in response to the injury, sent up a flurry of watersprouts from the healthy wood below the damaged area. It was providing new leaders to replace the doomed leader. The world, being the perverse place that it is, of course that tree didn't suffer any storm damage. It will be ready though, when the time comes.