Warrenheip and Maungatautari
Abundance of weta in a pest-free environment
Several species of cave weta (Rhaphidophoridae) and tree weta (Hemideina spp.) occur at Warrenheip. Ongoing studies of these nocturnal creatures document abundance and diversity, both within the Warrenheip reserve and outside it, in order to track changes over time. This information will be used to assess whether weta are useful indicators of ecological changes following eradication of mammalian predators.
Ground dwelling and soil invertebrates as indicators of change at Warrenheip
This DRP was commenced by an EcoQuest student during the period February to May 2000, and was repeated a year later. The aim of this study is to record changes in the invertebrate fauna within the pest-free Warrenheip reserve using pitfall traps to compare the composition and abundance of the invertebrates with those found in pitfall traps in adjacent areas where pest eradication and /or restoration plantings have not occurred.
Monitoring of newly introduced endemic fauna in Warrenheip Reserve
Since 2001, juvenile Northern brown kiwi, Mahoenui giant weta and pateke [brown teal] have been translocated to Warrenheip. Some of the kiwi and pateke were fitted with radio transmitters. Students monitored the movements and habitat use of the kiwi and pateke using radio telemetry. The first 100 Mahoenui weta to be translocated were tagged and numbered. A small number of the weta also were fitted with radio transmitters. Students monitored dispersal and habitat use of the weta by visual searches of the release sites and surrounding habitat, as well as radio telemetry. During subsequent releases of Mahoenui weta a trial was run, using diodes and transponders to monitor and relocate the weta.
Survey of the flora and fauna of the Mangahanene Stream and evaluation of the state of the aquatic habitat within the Warrenheip reserve
The aim of this study was to develop, and trial, repeatable field techniques for grading sections or reaches of streams for their state of health, and techniques for determining priority management requirements in order to improve stream health. The focus was on user-friendly, low cost, effective field methods for stream assessment that can be used by landowners to determine management priorities of the (sections of) streams that flow through their land. EcoQuest students applied stream-testing techniques, using sections of the Mangahanene Stream, which flows through the Warrenheip reserve.
Community structure of invertebrates (ground dwelling and arboreal) on Maungatautari
These projects marked the beginning of a long-term study. The aim is to measure, track and document community changes in response to removal of mammalian predators following completion of the predator-proof fence. In 2004, students carried out baseline surveys on diversity and abundance of invertebrates within the cells, immediately following predator eradication efforts, and outside of these cells, where mammalian predators are still present. Invertebrate communities were sampled, using pitfall traps and beating of vegetation, inside and outside the enclosed cells, on both sides of the mountain. In addition, sampling was carried out at several elevations outside the enclosures.
The invertebrate team caused huge excitement when an adult male Hochstetter’s frog (Leiopelma hochstetteri) turned up in one of the pitfall traps. Unfortunately, the frog had died in the trap. Traps were immediately closed, and Dr. Matt Baber surveyed the surrounding area for live frogs. Two more were found the same day, a further 10 (including juveniles) were located that week, and a second colony of the frogs was found elsewhere on the mountain in subsequent weeks. Hochstetter’s frogs are an endangered species, and had been assumed locally extinct on the mountain. This was the first new find of a population of this species in a decade!
Flowering & fruiting phenology, and community structure of vegetation on Maungatautari
Typically on the New Zealand mainland, flowers and fruit of native vegetation are consumed by introduced possums, and much of the seed that does reach the forest floor, is eaten by rodents. If goats and deer are present, seedlings and saplings are much depleted in the browse tier. Permanent transects and vegetation plots were established and surveyed, both inside and outside the enclosed cells, on both sides of the mountain. In addition, sampling was carried out at several elevations outside the enclosures. Diversity and abundance of plant species, forest structure, as well as seedling abundance were described. It is anticipated that there will be changes in abundance and diversity of plant and tree species following the removal of mammalian pests and predators.
A baseline study of plant phenology was carried out, to facilitate documentation of changes over time. This study was the beginning of an assessment of food availability for species that will eventually be reintroduced / translocated to the area, following the eradication of pest and predators.
Pest-proofing waterways
One of the challenges of using pest-proof fences is how to provide for fish passage, while preventing small mammals from entering the reserve areas using waterways. Special floodgates have been designed by XcluderTM. In 2004, students investigated the movement of fish, and the escape behaviour of rats in a small enclosure on the outside of one of a floodgate, where a pipe for fish passage was installed below the gate. No native fishes were found in the streams. Rats were trapped and released into the enclosure, and their behaviour was recorded. There is a lot more work to done on this aspect of ensuring the mountain can become free of mammalian pests.
