NORDIK Barrborn Crow Set. The NORDIK Barrborn Crow Caller Series is specially designed to produce an extra wide range of different crow sounds. Easy to Use. Includes Locker "Basic Crow" and "Pro Crow". The Locker "Basic" produces softer sounds such as the familiar cry when crows declare the area safe. The Locker "Pro" can generate a whole range of aggressive sounds that irritate and attract the c