Not sure on that. What breed are they? I know with Cotton Patch you can tell male from female at hatch by color, Males are lighter than females, but that is because their color is sexlinked, as well as Autosexing (genders are different colors at birth). If they aren't an autosexing breed there is no way to tell without genetic testing or vent sexing, and from what I'm seeing, in the autosexing breeds the males are white or predominately white...
If that was a Cotton Patch, which it's not, I would say female, would be better if there were two (of differing gender) to compare, but like I said, that may not be accurate if they aren't an autosexing breed...