A mini-marsupial that engages in killer sex sessions has been found to cannibalise the males after frenzied mating.
Males of the antechinus species die from stress after their breeding season due to their large testes, with trysts lasting up to 14 hours.
The mouse-sized marsupials that are only found in Australia "mate promiscuously in frenzied bouts" during a breeding period lasting up to three weeks.
Female antechinuses' litters often have multiple fathers.
Certain "stress-induced" death follows for all male antechinuses after the breeding period, said Associate Professor Andrew Baker of Queensland University of Technology.
"Unfortunately for the males it's a physiological quirk that happens to them - their testes are so large," Prof Baker told AAP.
"It produces so much testosterone for their size that ... a physiological switch that is involved in stopping stress hormone cortisol from leaking all through your body ... fails.
"The cortisol just goes unbound all through their body ... and essentially it's just poison."
Male antechinuses have a lifespan of roughly one year.
Prof Baker's research has discovered dead males provide "cheap energy" for fellow members of their species.
Photos have emerged of both males and females eating their own.
The pictures of mainland dusky antechinuses feasting on a male were taken on a trek to Point Lookout in New England National Park, NSW, in August.
Cannibalism may have its benefits for antechinuses, Prof Baker said.
"For the earlier-breeding antechinus species, it may mean that pregnant and lactating females can get high-energy food by cannibalising the males of the later-breeding species as they die off," Prof Baker said.
"For the later-breeding species, both sexes may take the opportunity to cannibalise dead males ... to help stack on weight and condition before their own breeding period commences."
Antechinuses are usually known to eat insects, spiders and sometimes small birds.
Prof Baker's research has been published in Australian Mammalogy.
