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

An intensive predator trapping programme was implemented in the upper Waita ki Basin. New Zealand from October 1997 to January 1998. The aim of the pro gramme was to prevent increased predation on vulnerable braided river fauna following decline in rabbits due to rabbit haemorrhagic disease (RHD). Fou rteen sites were trapped using a standardised method, and trap catch result s provided a relative index of predator abundance. In 101 650 trapnights, 1 067 hedgehogs, 328 ferrets. 196 cats, 96 rats and 69 stoats were caught. Pr edator guilds varied among sites and guild composition tended to change thr ough 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 area s were high. This study provides baseline information on predator abundance and predator guilds in the upper Waitaki Basin against which future trappi ng programmes can be compared, in order to assess changes ill predator popu lations since the introduction of RHD.