Adult swans typically nest in pairs, rather than in colonies, and don’t necessarily mate for life. According to the University of Michigan Animal Diversity Web, mute swans have been seen with up to four different mates and have also been known to leave one mate and pair up with another. Pairs do remain together throughout the breeding season, but may switch partners the following year. Together they build a nest that can be as large as 6 feet across where they will hatch as many as nine babies.
The male swan, called the cob, helps the female, known as a pen, to look after their babies, called cygnets until they are a year old. The young don’t spend more than one day in the nest once they hatch. If the pen is still brooding eggs, the cob will take care of any cygnets that have already hatched, leading them directly to the water. Though they can swim from birth, cygnets may sometimes ride on the backs of their parents or take shelter under their wings until they are old enough to strike out on their own.