Squamata: Varanidae
Varanus pilbarensis
I was sitting in a shady rock recess watching and photographing birds coming into the waterhole in front of me when I was surprised by this Pilbara Rock Monitor wandering past me on its way down the rocks.
It hadn't seen me and while it was out of sight investigating a crevice below me I quickly changed the camera lens to one more suitable for a close-up subject.
The monitor reappeared and this time it was my turn to be the surprise. It stopped in its tracks momentarily, and then bolted up the rock face past me and disappeared.