Not really. Flash hasn't scared away birds from what I've seen, even skittish ones.
+1 - I like shots just like the one you attempted, but would be lost w/o flash esp. on crop - that's why I got the 600rt with the 200mm reflector.
The FX-3 with a 600EX-RT on a RRS B91-QR flash bracket with an FA-QREX2 extender.
Looks nice, but it's always a hassle to order from the US to Europe (shipping time/fees & customs)...
... thus the question: does the "Better Beamer" make a big difference on 300mm vs. the plain 600rt (200mm reflector)? For what I'm shooting the 600rt seems to have enough juice even for 300mm on crop - or does the larger light surface result in significantly softer shadows?