Malung, Sweden: Jennie Tiderman-Osterberg lets loose a high-pitched call into the Swedish forest, her voice rising and falling in a haunting, eerie melody.
The echo reverberates through the woods and moments later, three cream and black cows emerge from the trees. The bells around their necks jingle as they make their way towards her to return to their shed. This is kulning -- a form of Scandinavian cattle-calling dating back to the Middle Ages.