How long after mating do black swans lay their eggs?

After mating and building the nest, there is approximately 2-3 weeks before the egg laying begins. Once the female begins to lay, she will produce a new egg every 12-24 hours and it can take up to 2-3 weeks before all the eggs are laid. Once she has laid all her eggs then the incubation period begins and usually lasts about 6 weeks before hatching. Males and Females alternate sitting on the eggs during the incubation period.