What is a female swan called?

A female swan is called a pen. Its male partner is called a cob. The pen's offspring that is one year or younger is called a cygnet.

A pen usually breeds in late April to the beginning of May. She lays a white egg every other day until it totals between five to nine eggs. While she incubates them for over 30 days, the cob defends the nest against possible predators. The newly born cygnets take to the water after one to two days. The cygnets' initial foods consist mainly of invertebrates and plants. Growing rather fast, they become fully feathered when they are nine to 10 weeks old and start flying once they are around 15 weeks old.