In the swan world, the males build the nests. Male swans will mate with a male or female swan (as long as the males are very young and introduced together as a young pair. If males are introduced at a later age without growing up together, they will not accept each other and fight).

Female swans will mate with a male or female swan (again if they are the same gender they must be introduced at a very young age or grow up together or the two females will not accept each other as a mate).

Male swans will mate with a male and build the nest with obviously, no eggs. Once the testosterone levels go back to normal, the boys will get the idea that they are sitting just to be sitting and will abandon the nest and go back to their normal daily routines.

Female swans will mate with a female and build the nest. One or both will produce eggs, obviously not fertile. Again, once their hormone levels return to normal, the females will recognize that the eggs are not viable and will abandon the nest to return to their normal daily activities. The Regal Swan