Johan Grotes and Joyce Kolk developed a trap sprung indicator to speed up their trap checking along the banks of the Wairaurahiri River that runs from Lake Hauroko to the sea in south-eastern Fiordland.
After seeing the sprung trap indicator in action John McIlroy reckoned it should be publicised far more widely. In many cases it could possibly save a lot of time checking trap lines. Together he and Kit Grigg came up with a slightly modified design that cost only about $1 per trap and could be installed within 2-5 minutes on DOC 150 and DOC 200 traps in the field. The basic materials are a small piece of pre-drilled treated timber (30x10x350 mm) painted orange, a woodscrew (SS, 8gx38 mm CSK Sq) and washer that acts as a pivot and a standard 100 mm cable tie.