weta

The advent of mammal-resistant fences has allowed multi-species eradications of mammals from ecosanctuaries on the New Zealand mainland. However, maintaining eradication of house mice (Mus musculus) has proven difficult, and at some fenced reserves they are the only exotic mammal present and reach a high population density. Over 5 years we examined the impacts of mice alone on biodiversity at Sanctuary Mountain Maungatautari by comparing forest blocks with relatively high and low numbers of mice.

Restoration of urban forest remnants is an increasing activity worldwide, but the effects of restoration efforts on local wildlife in urban remnants remain poorly understood. Understanding the benefits of restoration can also be confounded because of difficulties in monitoring the abundance of representative species, or understanding their ecological requirements.

Brodifacoum is a second-generation anticoagulant used for rodent control in New Zealand. Concerns about the poisoning of non-target species have resulted in restrictions being imposed on the mainland. It is, however, still commonly employed on offshore islands. Previous research investigating the poisoning risks of brodifacoum has generally focused on birds eating brodifacoum bait (primary poisoning) or through depredation of live rodents or carrion containing brodifacoum residues (secondary poisoning).

Most research into the diet of stoats in New Zealand has been in low altitude valleys such as the Eglinton and Hollyford Valleys. Yet much of New Zealand’s national parks (e.g. Fiordland National Park) consist of many small montane valleys and alpine areas. This research identified the key prey species of stoats inhabiting such small montane valleys and alpine grasslands.

Melanic and non-melanic mountain stone weta Hemideina maori (Orthoptera: Anostostomatidae) from the Rock and Pillar Range exhibit differential rates of melanotic encapsulation, a response to the presence of pathogens within the body. Because pathogens normally enter the body via food contamination, we hypothesised that dietary differences between the colour morphs might exist. We used faecal pellet analysis to determine the diet of the mountain stone weta.

European hedgehogs (Erinaceus europaeus) have recently been identified as a conservation threat in New Zealand. Hedgehogs were kill-trapped at 14 wetland and braided riverbed sites in the upper Waitaki Basin between late October 1997 and early February 1998 and their gut contents described. The most commonly eaten prey were Coleoptera (present in 81% of 192 guts), Lepidoptera (52%; n = 192), Dermaptera (49%; n = 192), Hymenoptera (42%; n = 192) and Orthoptera (31%; n = 319).

Artificial refuges and mark-recapture techniques were used to monitor the non-target impacts of handbroadcast application (simulating aerial application) of Wanganui No.7 cereal-based baits containing 0.15% (1500 µg g-1) 1080 on populations of weta and other invertebrates in Tararua Forest Park, North Island, New Zealand. Wellington tree weta (Hemideina crassidens) and a cave weta (Isoplectron sp.) were the only species of weta that occupied the refuges.

The mountain stone weta Hemideina maori, a tree weta, is a cold-adapted New Zealand insect that shows increasing body size with increasing altitude and decreasing temperature. This study modelled the monthly survival probability of adult weta at three sites (high, medium and low altitude) in the Rock and Pillar Range, Otago. Survival was predicted to be lowest at the low elevation site where weta are at the lower limit of their current altitudinal range. A total of 504 adult weta were marked and released at all three sites between November 1999 and May 2002.

The most distinguishing feature of the tree weta genus Hemideina (Orthoptera: Anostostomatidae) is their cephalic weaponry, which is thought to be the result of sexual selection on males to aggressively defend groups of reproductive females. Mountain stone weta H. maori is a tree weta that shelters in cavities under flat rocks on rocky outcrops in the alpine region of the South Island.

Tree weta (Hemideina) are an important component of New Zealand forest ecosystems and have been identified as possible invertebrate indicator species in restoration programmes. We present designs for artificial weta roosts that have been used to monitor tree weta in Hawke's Bay for five years. A variety of invertebrates use the roosts including two species of Hemideina. Our data suggest that occupation of roosts may take a number of years, each roost monitors a very limited area, and that occupation by invertebrates fluctuates seasonally.