A dog would circle three times (sometimes even more) before lying down. No one would really know the reason behind this peculiar behavior of a dog. Animal behaviorists believed that this is an inherent habit handed down by ancient dogs that lived in the wilds to the modern domesticated dogs.
Circling before lying down is a dogs defensive behavior. Dogs in the wilds would make sure that the location they have chosen to bed is not occupied by snakes, scorpions and other dangerous animals. By circling around before napping, the dog will see possible threats. Wolves stay in packs. This action is also the dogs way of knowing the location of other dogs in the pack.
Another reason for this odd behavior is comfort. The dog would circle around before lying down to tamp the grass, to compress the snow or to remove loose stones underneath the dirt that will make the bed uncomfortable. On a hot day, the cooler layer of the dirt is exposed when the dog circles the area it has chosen to lie down. The dogs coat serves as insulation against extremely cold weather. However, in the snow, these dog sleep together to take advantage of each others heat. By circling around, the dog will know from which direction the wind is blowing. The dog can then take the position that is most comfortable. Circling around can have another meaning when the dogs sleep together. The dog circles around to get more room and to warn the others not to encroach on his marked bed.
Circling around before lying down is the dogs way of marking its territory with its one of a kind scent. It would not be unusual to see a dog pee a bit on the place it is circling before it flops down. The dog is telling other dogs “Hey, this is my territory”. The dog is marking the territory so that it can be found again easily.
It is quite amusing to see a pampered dog circling the soft padded bed before slumping down. Certainly, the dog does not have to make a comfortable bed “comfortable”. So why then would the dog circle before lying down? Pet dogs actually don’t have to make their bed comfortable. Neither do they need to make sure that their bed is occupied by snakes. Its just that circling before lying down is an ingrained habit, similar to the humans habit of drinking a glass of water or flopping the pillows before lying down to sleep.