Most swans breed once a year. The Australian Black Swan is the only swan species that breeds twice a year. Now, having said this, it also depends on the habitat, individual swan and the flock.

Animals and birds can practice what is called stability- quasi equilibrium meaning carrying capacity of the habitat. If whatever reason, such as environmental, man-made or other catastrophe, the natural resources cannot support a certain number of animals/birds, the wildlife will practice a form of birth control. The flock/herd will never go above or below the carrying capacity of the habitat. If there is a large loss due to disease, hunting, predation or general disturbance of flock/herd numbers, the wildlife will reproduce to reach the carrying capacity. Additionally, if a certain species is significantly reduced in an area, then another species will attempt to fill the vacuum.

This is why we vehemently oppose the killing of Mute Swans in the U.S. based upon non-scientific research showing the swans are exponentially increasing in certain areas. If the carrying capacity of the habitat cannot support a large number of birds or animals, they will not reproduce. So, in most instances, when everything is well with the habitat and the flock, the swans will produce yearly to maintain the carrying capacity of the habitat. The Regal Swan