Swans. Male swan (called a cob) Female (called a pen) Swans usually form pairs for life. The young or baby swans are called cygnets. Swan nests are usually a large pile of reeds and water plants. Female usually lays four to six eggs. She incubates them until they hatch about 30-35 days later.The male guards the nest from predators and may take over incubation so that the female can feed. The babies emerge short-necked and thickly downed.