Seaecho, the staghorn will probably be fine but those "lesions" will never go away. Ultimately, as the fern ages, these fronds will be naturally lost and you'll then have a pristine plant again. That might take a year or two though. I have had squirrels damage a few fronds over the years, and yes, what I see on yours is similar to the damage the squirrels did to mine. The mouse may be the answer to our question.
