All swans mate throughout the year as a bonding process. However, to produce a clutch of eggs, Mute Swans mate in March/April while Black Swans produce a clutch of eggs in January and in the summer.

We have been researching swans for 10 years and mating behavior. We have seen acts which look like an attempt to copulate between black swans and mute swans, but with no success in producing offspring. There may be an anatomical disparity which prevents such pairings.

However, we do know individuals who have intentionally mated black and mute swans and produced what is known as a "blute" swan, but again, this is a rarity in the natural setting. The Regal Swan