The sire can be carrying agouti and you wouldn't know it with out testing or breeding. Agouti (which is basically bay, brown, and wild bay) only affects black so it wouldn't show on a red based horse like the sire.
His mane and tail are both black, so he's going to be a bay, I'm pretty sure.
Our filly was born a little lighter than this, and is now a dark brown, chocolatey color. I'm not sure what the exact term is for it.