Cane toads have been found moving around during the day in some shaded parts of Western Australia despite the toxic pest usually being nocturnal.
It is believed the dreaded amphibians are active at night in Australia to avoid the heat.
But the Kimberley region has sandstone gorges, some of which offer enough shade to provide more comfortable habitats.
Just several kilometres away, at more exposed sites, other cane toad populations remain nocturnal.
Macquarie University researcher Simon Clulow said it was surprising to see the species change such fundamental behaviour.
“This suggests that cane toads are particularly good at changing their behaviour in response to their environment, something known as behavioural plasticity, which might assist their invasive spread into new environments,” he said.
The team looked at cane toads near the invasion front in El Questro Wilderness Park from 2013 to 2015.
Using remote cameras at eight locations, researchers monitored the toads’ activity and dissected some that were active during the day to examine their eating habits.
Lead author Sean Doody, from the University of South Florida St Petersburg, said the team found toads that were active during the day were more likely to flee from an observer than nocturnal toads.
“This increased wariness may have been due to them being at higher risk from predators at night, or being more conspicuous to predators during the day,” he said.
It is not known whether the toads preferred being active during the day, or if the change was beneficial.