Undertaking one of the world’s largest and longest-running tracking programmes of its kind, Professor Craig Franklin — School of Biological Science at the University of Queensland and also Director of Research at the Steve Irwin Wildlife Reserve — focused on the responses of saltwater crocodiles to changing environmental conditions, including the impact of human-induced environmental change.
To gather data, Franklin’s team — including Steve Irwin’s daughter, Bindi Irwin — surgically inserted transmitters into more than 150 saltwater crocodiles, enabling the researchers to monitor the locations and body temperatures of the animals.
“The reason that we measure the crocodiles’ body temperature is that it governs, to a major extent, the physiology of organisms, from how they move to how they process food and how long they can stay underwater,” explains Franklin.
The resulting 5 million individual recordings from the reptiles yielded some surprising findings: “We have had some beautiful results that show that a small increase in water temperature has a huge impact on the crocodiles’ ability to hold their breath underwater,” says Franklin. “We’ve seen crocodiles dive for up to seven hours at a time.”
The study looked at saltwater crocodiles from a tropical river system in Australia, whose body temperatures were found to conform to their aquatic environment, mimicking the temperature of the water.
“That goes against the paradigm for crocodiles in that they bask and warm up,” says Franklin. “That doesn’t seem to be the case with our animals.”
Main image: The study looked at the effects of climate change on saltwater crocodiles living in tropical river systems in Australia. © iStock