In what may be the ultimate sacrifice for lust, Australian scientists have discovered why the males of some species of marsupial are dying for sex.

Scientists have pondered for decades why the males of more than a dozen native species of insect-eating marsupials, including many small rodent-sized antechinus and phascogales, die not long after mating.

Agile antechinus. Credit:WWF Australia

A team led by Diana Fisher, of the University of Queensland, has confirmed the behaviour, known as dying off , was driven by the males' attempts to out-compete each other to father offspring during the short time females were fertile.

"The [males] spend all their energy mating," Dr Fisher, an Australian Research Council future fellow, said. "They have lots of partners. They have really long mating sessions, up to 12 to 14 hours in the case of antechinus."