The composition works nicely with a great view of the chick and its open bill. I would darken the sand a little and also make the blacks on the adult a little blacker.
Nice capture Harold, with just enough green in the background to provide some needed separation. The simultaneous calling and begging poses are great! I wouldn't mind a little more sharpness on the adult, but that is a tall order with that kind of magnification. I wonder if the Shadow/Highlight tool could help provide a bit more separation in the whites around the adults throat?