The largest number of mute swan eggs on record is 13 and we have had a pair that had 10 eggs, 9 of which hatched. So, swans can produce 1-13 eggs.

Swans of the same gender will mate and go through the nesting phase. Two males will mate, build a nest and sit until they get tired of sitting. Nature instills in animals and birds the need to mate and nest. Obviously, with 2 male swans you will get a nest, but no eggs. Male swans usually are responsible for building the nest.

Female swans will mate and produce eggs. Both females may be producing a clutch so one bird may or may not be responsible for the large number. If there is no male, the females will build the nest to have a place to lay the eggs. Obviously, the eggs will be infertile.

We had a case where owners donated a swan stating that the bird was a female and pinioned. When we got possession of the swan, it was able to fly (not pinioned) and was actually a male. The owners had the bird for many years. Frequently, people will purchase or take possession of swans from individuals who will state that they are sure that the gender is correct, without having any true gender tests conducted which leads to confusion during the mating/nesting season.

Unless you have the swans DNA sequenced or cloacally checked by a veterinarian there is no accurate way to determine the gender just by looking at the birds. If you get the birds checked, please let us know the results. It will be interesting to know if what you think you have is actually what you have in your possession. Good luck. The Regal Swan