Diurnal basking (sunning) is common in many ectotherms (cold-blooded animals) and is generally thought to be a behavioral mechanism for thermoregulation. Recent studies have reported the occurrence of nocturnal basking in a few distantly-related species of freshwater turtles, but the true extent of this behavior is unknown. Therefore, scientists from La Trobe University and elsewhere initiated a global, collaborative effort to systematically document and quantify diurnal and nocturnal basking activities across a wide range of freshwater turtle species and locations. They conducted camera trap or manual surveys in North America, the Caribbean, Europe, Asia, Africa, the Seychelles, and Australia.
“We first observed freshwater turtles nocturnal basking at the Ross River in Townsville, Australia,” said Dr. Donald McKnight, a postdoctoral researcher at La Trobe University.
“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.”
“We think it’s related to temperature,” he added.
“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.”
For the study, Dr. McKnight and his colleagues collected 873,111 trail camera photographs (25,273 hours of search effort) and obtained data on 29 species of freshwater turtle representing seven of the 11 living freshwater turtle families.
They collected data from Africa, Asia, Australia, Central America, Europe, North America, the Seychelles, and Trinidad and Tobago (in the Caribbean); however, most of the data came from Australia and North America.
In most cases, a minimum of three wildlife trail camera traps, set to time-lapse mode (two-minute photograph…
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