I just realized that all this seriousness about this theme is "for the birds" ;-) We're never gonna nail it down! So here's one for fun:
1. It's a significant event (in the birdie world);
2. Of short duration;
3. Has the organization of forms which gives the event it's proper expression;
4. Has the static and the dynamic and the synergy between the two;
5. Unrepeatable? Naww... probably not... he's gonna get the same look again if he doesn't get the next sunflower seed.
Close, but no sunflower seed...
On second thought, 4 outta 5 ain't bad... is it? ;-)