Well done! I second the comments made by David Wu SoftDev.
Great job of drawing and smoothly animating the flapping bird sprite, and nice shading to add depth to it.
It's great to see the difficulty gradually increasing with more and more enemies of different types as you progress further.
It's also really nice that death doesn't mean starting over, however I did find myself getting a bit impatient waiting for the revival to happen. At least it gives you extra motivation to try harder not to get hit, though.
Nice entry!