it's too big. try pixelling at maybe half the size it's at now.
stop dithering. it isn't helping.
don't use black in just one spot. if your use of black isn't consistent, then it flattens the image.
clean your lines. plenty of jaggies in there. use aa to smooth out the unavoidable jagged line segments.
use hue shifting. it makes a palette much more interesting.
break the monochrome look. unless his beak and talons are made of the same stuff as his feathered body, they should be a different color.

And most importanly:
use references, preferably photgraphic. if you are using references, post them.