Relative abundance of mammalian predators in the upper Waitaki Basin, South Island, New Zealand

An intensive predator trapping programme was implemented in the upper Waitaki Basin. New Zealand from October 1997 to January 1998. The aim of the programme was to prevent increased predation on vulnerable braided river fauna following decline in rabbits due to rabbit haemorrhagic disease (RHD). Fourteen sites were trapped using a standardised method, and trap catch results provided a relative index of predator abundance. In 101 650 trapnights, 1067 hedgehogs, 328 ferrets. 196 cats, 96 rats and 69 stoats were caught. Predator guilds varied among sites and guild composition tended to change through time; for example, stoat and rat catch rates increased. Cat and ferret catch rates Increased in the last month of trapping, which suggested that juvenile dispersal and immigration by adult predators from surrounding areas were high. This study provides baseline information on predator abundance and predator guilds in the upper Waitaki Basin against which future trapping programmes can be compared, in order to assess changes ill predator populations since the introduction of RHD.