By stretching a line along the pond side, which is invisible for herons, the access to the pond will be blocked. The ringing noise of the little bells will prevent a heron for days at a stretch from making another attempt. The line can be applied simply and nearly invisibly. The length of the line is sufficient to protect ponds with a circumference of 12.5 metres. The supply includes 8 rods, 25 metres of nylon line, 8 jingle bells.