Freshwater turtles found basking in the moonlight

Nocturnal basking has only recently been reported in wild freshwater turtles, but this study suggests that the behaviour is widespread and occurs in many species.

Postdoctoral Researcher at La Trobe University Dr Donald McKnight said he first observed freshwater turtles nocturnal basking at the Ross River in Townsville.

“They were coming up at night and sitting on logs exhibiting very much the same behavior they do during the day; when we looked into it, it wasn’t something that turtles reportedly did,” Dr McKnight said.

“We think it's related to temperature. The water is staying so warm at night that it's actually warmer than the turtles like to be and they can cool down by coming out of the water.”

“It’s widespread across the turtle family tree, with the caveat that it is only in the tropics and the subtropics where it occurs,” Dr McKnight said.

Dr McKnight first observed the behaviour with a colleague, Dr Eric Nordberg at the University of New England, on the banks of the Ross River in Townsville, Australia.

For this study a team of researchers from around the world put cameras on basking logs to monitor the nocturnal activity of as many freshwater turtle species as possible.

Cameras taking one photo every two minutes were set up in 25 locations across Australia, Belize, Germany, India, Seychelles, Senegal, Trinidad and Tobago, the USA and South Africa. These captured data on 29 species from seven of the freshwater turtle families.

The study Nocturnal basking in freshwater turtles: a global assessment, was published in Global Ecology and Conservation.