The deer around here are hungry with all of this snow. I posted some pics the other day of them near a bank covered with ground cover. Here is what they were after. Since it hasn't budded yet it should come back as good as new this spring. They were after it 5 or 6 years ago and it came back fine. I really feel sorry for them as all of their natural food is covered with 26 inches of snow. Once it melts and they can find their natural food again, then they will leave the ground cover alone.
The deer are saving you the trouble of trimming back your ground cover and they're getting a meal into the bargain. I'm sure the plants will be just fine.
I do feel bad for the deer at this time of year or when there is too much ground cover We were not allowed to feed when we lived in the country...when the spirea here are eaten by the rabbits they come back as good as new...they save me from trimming, I just wish they would do all of them and not just eat one or two to the ground....
The local newspaper carried a couple of appeals for farmers to start feeding deer. The snow cover's so deep they can't find enough to eat and will need help from now on until the grass is growing again. We'll still hunt them in autumn but at least they won't suffer now.