Any kangaroo out in the open is in serious danger of overheating.
In the full sun, the temperature on the ground soars to 70 degrees.
By midday, the radiation is so intense they must take shelter.
In the shade, they are shielded from much of the sun's energy
but their body temperature can still rise.
So they lick saliva onto their forearms
where there is a network of blood vessels close to the surface of the skin,
and as the saliva evaporates, their blood is cooled.
This thermal image shows just how effective the process is.
The blue areas on the body are the cooler parts.
As the saliva dries, it has to be replaced.
And this is a real drain on the kangaroo's body fluids.
Even in the shade, the earth is baking hot.
So the kangaroos dig away the warmed topsoil to get at the cooler ground beneath.