Endangered male Northern Quolls are giving up sleep in favour of having more sex – and it could be killing them, according to new research led by the University of the Sunshine Coast.
The study investigated why male Northern Quolls (Dasyurus hallucatus) – carnivorous marsupials the size of a small cat who usually mate themselves to death in one season – do not survive to breed again while females can live and reproduce for up to four years.
The findings, published today in Royal Society Open Science, suggest not enough sleep is contributing to the post-breeding die-off of males.
“They cover large distances to mate as often as possible and it seems that their drive is so strong that they forgo sleeping to spend more time searching for females,” says UniSC Senior Lecturer in Animal Ecophysiology Dr Christofer Clemente.
“Something is definitely causing their health to fail after just one season and we think it is linked to sleep deprivation,” Dr Clemente said.
“The dangers of a lack of sleep are well documented in rodents, and many of the traits associated with sleep deprivation we see in male quolls, and not in females.”
He said the male quolls lose weight, become aggressive and appear to be reckless when it come to their survival.
To make the most of their one breeding season they also let themselves go when it comes to their appearance. Their condition declines, with a notable increase in parasites, mostly likely because they devote less time to grooming.
Unusual breeding strategy
The Northern Quoll is the largest mammal known to invest its energy into just one breeding season, a strategy known as Semelparity, however the cause of death is unknown.
As part of the collaborative study with The University of Queensland, researchers fitted backpacks with trackers on wild roaming male and female Northern Quolls on Groote Eylandt, off the coast of the Northern Territory, Australia
Lead author, UniSC PhD candidate Joshua Gaschk said the behaviours, activity budgets, speeds and distances travelled were measured to track differences between males and females.
“Male quolls breed for one season, while females can breed for up to four, so this suggested that if no difference was detected in their daily behaviours that they perish due to an unexplored aspect of their physiology,” he said.
“Instead, we found that male and female quoll behaviour differed significantly in many ways.”
Overall, males spent less time sleeping and resting than females. They walked more and travelled longer distances. Males were also not as vigilant when it came to searching for food and eating, avoiding predators and grooming.
“Sleep deprivation, and associated symptoms for a prolonged duration would make recuperation impossible and could explain the causes of death recorded in the males after breeding season,” Mr Gaschk said.
“Two males, who we named Moimoi and Cayless moved for 10.4km and 9.4 km in one night respectively. An equivalent human distance, based on average stride length, would be around 35-40km.”
“They become easy prey, are unable to avoid vehicle collisions, or simply die from exhaustion.”
Researchers say the initial data highlights the need for further studies to provide insights into the effect of sleep deprivation on quolls and the wider Dasyuridae and Didelphidae families of marsupial mammals, found in Australia and Papua New Guinea.
“We want to determine if sleep deprivation is experienced by other family members, such as opossums, antechinus (marsupial mice) and Tasmanian Devils,” Mr Gaschk said.
“Virginian opossums (Didelphis virginiana) undergo a similar physiological change to other semelparous species but do not experience the die-off, while Tasmanian devils (Sacrophilus harrisii) experience a similar loss in condition and a reduced immunocompetence.
“If male quolls forgo sleep to the detriment of their survival, Northern Quolls become an excellent model species for the effects of sleep deprivation on body function.”
The study was supported by the Australian Research Council through a Discovery Projects Grant
Media enquiries: Please contact the Media Team media@usc.edu.au