Both wolves and coyotes responded to the presence of the other species with increased marking. Coyotes reacted actively by overmarking scent marks left by wolves. The wolves' reaction was more passive. They investigated the coyote marks and occasionally overmarked them. The alpha male is the primary RLU scent-marker with occasional instances of other wolves using RLUs.
Wolves mark the borders of their territories with RLUs.
These scent marks stop other wolves from entering the area. RLUs also provide a scented map for wolves as they travel through their own territory. During times when the pack temporarily separates, scent marks, such as SQUs and scats, provide information about which portion of the territory has been hunted. Lone wolves do not leave scent marks because they do not want to attract the attention of resident packs. When two loners of the opposite sex meet, they use scent marks in the form of RLUs and SQUs to communicate.