Discovery and spatial assessment of a Hochstetter's frog (Leiopelma hochstetteri) population found in Maungatautari Scenic Reserve, New Zealand

We describe the discovery, genetic status, and survey of a Hochstetter's frog population (Leiopelma hochstetteri) found in Maungatautari Scenic Reserve, New Zealand. The strongest genetic affinities of the Maungatautari population are with a population of frogs at Mt Ranginui, approximately 55 km away, according to the single genetic sample taken. Frogs were found over an area of at least 120 ha on Maungatautari, and the encounter rate (0.66 frogs/person hour) and relative abundance (2.7/100 m) was low compared to most other populations. The survey results suggest that the population is relatively small, and that introduced mammals, particularly ship rats (Rattus rattus) and feral pigs (Sus scrofa) may pose a significant threat. Weather conditions and observer experience/bias were also likely to have influenced our results. Eradication of introduced mammals from Maungatautari is scheduled for late 2006. Continued monitoring of frogs will document their response to mammalian pest eradication, and the functional importance of Hochstetter's frog in a large mainland island free of introduced mammals.