That over a quarter of the population of black swans exhibit homosexual tendencies?
A flamboyantly homosexual swan couple and their brood.
Swans are more or less monogamous water birds. They reinforce their pairings with frequent preening and sex. Should one die, the other usually lives out the remainder of it's life alone. Generally, when two male swans pair off, one mates with a female, she lays eggs in their nest, and then they chase her off. And because the males are so much bigger, their baby cygnets have up to ten times the survival rate as their hetero counterparts.