[srcreigh]

In this case a better indicator is that Ravens can use thermal winds to effectively float in the air, while crows can't and have to flap.

[BugsJustFindMe]

"Can/can't" isn't a great general indicator, because "doesn't" doesn't imply "can't" except circumstantially. If you see a bird floating, it might be a raven. If you see a bird not floating, you still have no idea.