Hej,
IMO, use wide angle (35mm), use Av F2.8 (or is it 2.6 on A570 IS), and choose a day with more light, and NO digital zoom. I think you need like 1/500s to get the body of the bird sharp. You need a lot of luck, too. ^^
Not sure how you can get the focus right, maybe hyperfocal at 2m something, or maybe fixed but with a DOF calculator, get a decent focus zone, depending where is the flower (potentially the bird) and where is the cam.
