Possums were introduced to New Zealand in the 1830s to start a fur trade. With no natural enemies their population totals 70 million – about 20 possums for every person. In one night 20 possums will eat 6kg of vegetation. That same number of possums will eat two tonnes of food, including native trees such as pohutakawa, rata, totara, kowhai and kohekohe, in a year. More than 400 possums have been caught in Waikowhai Reserve since the Auckland Predator Control Programme began in 2004.