Aerial Gymnast ?

I spent much of an absolutely gorgeous Monday morning in the Peter Murrell Reserve at Kingston. The reserve was very much alive with bird activity, and two of the more obvious denizens, were the Swamp Harrier and the Brown Falcon. The harrier spent much of its' time, soaring and calling, announcing to others that this territory was occupied. At the tree top level, the Brown Falcon, was noisily calling and performing fast fly pasts. As I walked back to the car park, I noticed the harrier hovering over the forest canopy, but I suspect that my appearance caused it to climb higher and start to spiral over the open ground. The 'brown' must have noticed this too, and followed suit, albeit at about 15 metres lower, mirroring the harrier as they both climbed higher. Although I was some distance away, I took the accompanying shots. As I was processing the images, I noticed that the 'brown' had its' head fully inverted (I assure you that I haven't manipulated the image!). Well I suppose that's one way of keeping an eye on a potential competitor!