Diversity and same-sex pairings in birds

Both male and female swans have been observed forming same-sex pairs in which they will court, nest, and rear eggs. Studies have found that this behaviour is more persistent in male swans than in females and particularly Australian male black swans, who form stable, long-lasting same-sex relationships with each other.

During courtship, male same-sex pairs of black swans have been seen performing courtship displays and mating behaviours, similar to those of opposite-sex pairs. They have also been known to chase off other opposite-sex pairs to steal their nests, including eggs. They will then incubate the eggs and raise the chicks.

Some studies have found that same-sex pairings have a higher success rate in raising chicks, about 80% compared to 30% in opposite-sex pairs. This may be because the pair of males can defend a larger territory, and the incubation duties are shared more evenly between the same-sex pair.

The iconic flying rainbow of Sydney, the Rainbow Lorikeet is a brightly coloured parrot that is native to the eastern coast of Australia. Both males and females of the species look identical, and it is impossible to identify their sex just by observing them.

They are known for their striking plumage, which features a bright red beak, blue-mauve head and belly, green wings, tail, and back, and an orange-yellow breast. Their distinctive coloration makes them hard to miss and is the reason for their name.

Rainbow lorikeets were abundant in the 1800s, became rarer between the late 1800s and 1950s, and have since recovered. Today, they can be easily spotted in many of Sydney's parks and gardens. Rainbow lorikeets are widespread in Eastern Australia and are also common in Perth.

Wild penguins have been observed engaging in same-sex courtship and pairing for decades. George Murray Levick, a British explorer, studied a colony of Adelie penguins in Antarctica in 1911-1912 and observed same-sex behaviour among the birds. His observations were documented in a paper, Sexual Habits of the Adelie Penguin, which was privately circulated among a handful of experts but not published widely due to what was deemed shocking material for the time.

In recent years, same-sex pairs of penguins in care have also been observed engaging in mating rituals, including the famous Sphen and Magic, a male pair of gentoo penguins at the SEA LIFE Sydney Aquarium. Staff were inspired to give them a second egg from another couple, which they successfully hatched, raising the chick together.