Ah yes.
A) Spaces between the pics. GOOD!
B) Bird looking. Good.
Sharp eyes, good DOF. Fill-flash in the last? NIce blue eye here .
500x333 pixels is very webfriendly, but also quite small (on my screen) ... you might try to go 600x400 or even 800x600 with bird pics, I think ... and you might consider cropping them so the bird is not always all centred (?)