Whoa! Great Egret Aerobatics

I made a brief diversion to Gould's Lagoon recently, while returning from a trip to New Norfolk. I had little time for anything but a quick scan, but seeing the resident Great Egret close to the highway, I couldn't resist getting out and taking a few shots. While it usually puts up with passing pedestrians, it was suspicious of my intentions, as you can see (top left image). However it allowed me to take a few shots before it flew a few metres, landed and carried on feeding. As I stood deciding whether to try for more shots, it took off again, calling with the usual croaking call, as it climbed ever higher, then circled some hundred metres or more over the lagoon. I watched, wondering whether I had been responsible for this action--I get, perhaps justifiably, paranoid about overstepping that indefinable line between legitimate watching and harrying birds, especially when attempting photography. So I stood there willing it back down to the lagoon, when it went into a series of high speed dives and loops, pulling what in an aircraft, would be described as high g turns. Frankly, I've watched many hundreds of egrets, but this display can only be described as awesome! As you can see, I shot off a few images, albeit from some distance away. If you look closely at the images (by clicking on them), you may see the distortion of its' body, particularly in the neck, during these high speed aerobatics. The whole episode was over in a matter of minutes, and it soon descended back to the lagoon, and after a few laps round it, landed on one of the decaying nest boxes, close to the hide. I returned to my car, quite relieved that the egret had returned, but still puzzled by the event. My thoughts as I drove back, were that perhaps it was a reaction to a predator, possibly a Peregrine Falcon, the local White-bellied Sea Eagle, or one of the overwintering Marsh Harriers, unseen by me. Perhaps you may have seen a similar display and have a better explanation. An interesting brief visit.