The only time I've been involved with owl nests (or any other birds of prey) was if a nest with babies got displaced. If they aren't actively nesting then it shouldn't be a problem, they usually build a new nest in the Spring anyway.
Greg, who is Moss?
If it's a great horned owl not only mice and gophers .They will snatch rabbits ,squirrels ,kittens . They can be just as active in day time as they are at night too .
Birds of prey for some reason fascinate me .