Northern Gannet (Morus bassanus) birds showing Fencing Behavior. This behavior is important for the birds to renew their bonds after fishing trips. Fencing is the first behavior a mating pair perform when reunited at the nest. This pair of birds is nesting in the gannet colony on Bonaventure Island, Quebec. Each bird makes a nest out of rocks, dirt, and seaweed. The nests are approximately a half meter apart. This is a motion analysis picture, made from eight images covering 1.3 seconds of time.