A plonka is a flat, wide stone used as the main component of a simple trap for catching small birds. The stone would be propped up with a stick and bait placed underneath. When a bird pecked at the bait, the stick would fall and the stone would trap it. These traps were often set on window ledges of upper floors. The most prized catch were birds from the thrush family, and the most common hunters were elderly women. The motive was often hunger, but also culinary tradition.