One sure fire method that has worked for us up here in Calgary has been a sprinkling of cayenne pepper over the area on the ground if they are reaching up and getting the buds from there. if they are hanging from the trees, a light sprinkling over the leaves may not damage the rose leaflets permanently-but you may want to investigate that further.In any event, once the critters get a blast of that stuff bail out fast and rarely return soon. Another thing is that it may have to redone if heavy rain persists.