Hunters Bob Cairns (left) and Geoff Alexander on Kāpiti Island in the early 1980s. The wooden stakes Bob is carrying were used to set up possum traps. One stake was driven into the ground, and a second one leant against it at a 45-degree angle. A gin trap was then placed on the angled stake – ground traps could not be laid, as kiwi would have been caught in them. The trapping campaign was followed by a mopping-up operation using rifles and trained dogs. In 1987 the island was declared possum-free for the first time since possums were released there in 1893. In the 1990s and 2000s, islands were usually cleared of other mammalian predators by aerial drops of edible pellets laced with the poison 1080.