Not sure that this really belongs in this forum but it is a Flash question more than strobist ??.
I hope Tony, Rich, Col etc will find it here.

On Saturday afternoon I spent some time down by a creek at Blackdown Tableland where there were quite a few species of small birds, Honey-Eaters, Thornbills, Fairy Wrens, Scrub Wrens etc, having their afternoon drink and bath.
I was relatively close, maybe 20 mtrs, once I had worked out their routine and found an appropriate bush to perch behind.

My problem is that a large quantity of the shots have got the bird "Flash Dancing"

40D, 580 EXII, 120-400 Sigma
ISO 400/800 1/250 f 8 / f6.3, -2/3 FEV

I tried Highspeed sync at 1/250, I tried dropping speed back to 1/200 (std sync speed), I tried first curtain syn and second curtain sync ??........

My question is - How to I prevent or minimise this behavior or is it just a fact of life ???