Ah yes, should have mentioned each image is likely to be of a different individual. It got a bit hard to keep track of them as they were chasing each other around a bit. I hadn't set the time on the camera correctly but they were recorded early in the morning, so I had wondered if the colour variation was down to the individuals wanting to warm up to being hot enough?
In two of these images you can clearly see the pale anterior edge to the ear opening which confirms tympanum. A clear side shot of the head is a great help here.