Why do dogs walk in circles before lying down?
Dogs often walk in circles before settling down for a snooze. This curious behavior is actually hardwired in them from prehistoric times. Fido's wild dog ancestors would walk in circles to make a nest — an area with stomped-down grass or underbrush where they could sleep. This behavior may have also driven out snakes or large insects that otherwise might have bothered them.
Moreover, a nest would mark the dog's territory, telling other dogs to stay away.