Call it sexist if you like but a type of threatened parrot has started favouring male offspring at the expense of female chicks as its environment changes.

Researchers at the Australian National University have discovered the swift parrot's breeding habits change much more quickly than previously thought when a predator intrudes on their area.

They produce more males to try to bump up the population.

The parrots have a new predator, a type of possum known as the sugar glider (it likes eating sugar). The sweet-toothed animal attacks female swift parrots in their nests. Because the mother parrots are sitting on eggs, they are easy prey.

"Female swift parrots can determine the sex of their offspring, and they are favouring boys over girls as they face diminished survival prospects in the wild," Professor Rob Heinsohn said.

"Instead of producing extra daughters to make up for a shortage of adult females they make sure their sons hatch first so they get more food and become more competitive in a tight mating market."

Read the full story at the Canberra Times website.