United States - April 17, 2025 Wolves defend their territory not just with teeth and howls, but also with smells. Wolf packs create a "smelly fence" to warn other wolves that the land is taken. Every week or two, a pack patrols the outer edge of its territory. They sniff around and leave scent marks, usually with the breeding pair peeing on trees, rocks, or shrubs. At the edge of their territory, wolves are twice as likely to scent mark compared to the middle areas. During patrols, they check for signs that other packs may have crossed into their land. If they detect another group’s scent, they know a trespass has occurred. However, not every interaction leads to a fight. Sometimes, meetings can be friendly, especially if a wolf is searching for a mate. This scent-based boundary system helps wolves avoid risky fights and keeps packs spaced out. It shows the complex social world of wolves, where information travels through smell as well as sound and sight.