Swans copulate throughout the year. But, depending on swan species (Black swans produce two broods of cygnets a year), most swans mate during the spring to produce eggs.

Copulation to produce eggs takes place approximately 2 weeks prior to the laying of eggs and nest building and continues daily until the first egg is layed. Then, copulation continues daily until the female swan has reached her allocated number of eggs that she is to lay. So, pregnancy in a swan may or may not mean the time that the female's hormones are high enough to instigate mating and the production of eggs. Once the female swan lays an egg, this means she is no longer pregnant. However, the swan is capable of producing 1-13 eggs so pregnancy again can be from one day to two weeks of age until all eggs have been layed. We hope this makes sense. The Regal Swan