The sex life of a tiny Australian marsupial known as an antechinus is already pretty bizarre. But now its mating season has gotten even stranger – and darker – thanks to the introduction of cannibalism, as observed by field researchers.
The great majority of these small marsupials live along the Great Dividing Range on the eastern coast of Australia. There are 15 different species of antechinus, with most living in hollow trees and resembling mice. What truly sets them apart from many other rodents and marsupials though, is their habit of mating so intensely each year that the males all drop dead after marathon bouts of sex that last for hours at a time during the animals' three-week breeding season.
“During the breeding season, male and females mate promiscuously in frenzied bouts lasting as long as 14 hours," said Andrew Baker from Queensland University of Technology's School of Biology and Environmental Science. "Certain stress-induced death follows for all males as surging testosterone causes cortisol to flood uncontrolled through the body, reaching pathological levels."
While the vigorous sex habits of the antechinus were no secret, what surprised Baker and his colleagues during recent field observations was what they saw after some of the animals' lengthy sex sessions. Two species in particular – mainland dusky antechinus and brown antechinus – were seen eating their dead comrades, in what has become the first photographed evidence of such behavior.
“Each species may benefit from eating dead males of the other," said Baker. “For the earlier-breeding antechinus species, it may mean that pregnant and lactating females can get high-energy food by cannibalizing the males of the later-breeding species as they die off. For the later-breeding species, both sexes may take the opportunity to cannibalize dead males of the earlier-breeding species, to help stack on weight and condition before their own breeding period commences."
In the study revealing the cannibalistic behavior, the researchers believe they found a dusky antechinus eating another member of its own species. They say that they are not sure of the sex of the feeding marsupial as both sexes eat during the high-energy mating season, but they suspect it is a male.
“The antechinus seen feeding on its dead comrade appeared vigorous and large-bodied, but it had damage to its right eye and hair loss on its arms and shoulders, which is associated with stress-induced decline in males," said Baker. "He was perhaps destined soon to become somebody else’s meal.”
This is the second instance of rare cannibalistic behavior in Australia getting caught on camera that we've reported on of late. The other was back in October and involved a black-headed python chowing down on a smaller version of its own species while it was still alive.
The new finding has been published in the journal Australian Mammalogy.