Tyler, the crow and owl hoot calls are to induce a "shock" gobble. Sometimes a gobbler will sound off at any loud noise, like the slamming of a car door. The owl hoot can be used early in the morning (before sunrise-when owls are vocal) to provoke old Tom to tell you where he is; you would not want to be using a turkey call because the birds would still be on the roost and not actively calling. You guys are making me envious with all this talk about turkey hunting!