Deeper, older cries. Crows attacking an owl. Attracts crows ready to join the action. Drive 'em crazy with this one. Mobbing crows attracts other to join.
Crows gathering from one to many, effectively calls others.
Single crow calls others to action. Crow cries create action. Large calling flock attracts snows and blues. Can be used for calling and tutorial. Recorded rattling of antlers attracts rutting bucks.