Jock-- They had a somewhat similar problem on the adjoining estate when I lived in Ireland; a couple of young thugs were coming up from Dublin on a regular basis and shooting fallow deer in the rump with a crossbow. The attacks stopped when a burned out car was found by the side of the road up in the Wicklow mountains and next to it were two lads whose legs had been worked over with a couple of heavy hammers. The Guards investigated, but in the end came up with no viable leads. However, the police presence during the investigation must have put the wind up whoever was responsible, because there were no further attacks on the deer herd.