The endangered New Zealand sea lion (Phocarctos hookeri) has recently been confirmed as breeding on Stewart Island/Rakiura, southern New Zealand. This area is thought to have the largest number of sea lion pups born outside of the New Zealand subantarctics. However, the sparse distribution and cryptic behaviour of this population means known human threats and their effects on the population will be difficult to determine, limiting conservation priority setting and management.
There is a lack of information about how elevation affects the distribution of ship rats in New Zealand. In this study, ship rats (Rattus rattus) were captured in traps set along a 2 km elevational transect (455–1585 m a.s.l.) in beech (Nothofagaceae) forest and adjacent alpine tussock at Mt Misery, in Nelson Lakes National Park, from 1974 to 1993. A total of 118 rats were captured.
Introduced mammalian predators threaten populations of endemic New Zealand skinks. Their effects on skink populations have been not often quantified on the mainland and are known primarily from skink population increases on islands from which mammals have been eradicated. Estimating skink population density with capture–recapture trapping is time-consuming and costly. Counting skinks in artificial retreats in specific weather conditions may be a useful and relatively quick way to index population density, but needs calibration for different habitats and species.
The study of amphibian spatial behaviour provides key information for species conservation. Most commonly used techniques to track amphibians are either unsuitable for small species or fail to give sufficiently fine-resolution data of habitat use. We report on the use of non-toxic fluorescent powders to track the fine-scale movement of a threatened New Zealand frog, Leiopelma pakeka.
While invasive rats are demonstrably inimical to indigenous vertebrate species, there has not been unequivocal evidence of benefit to invertebrate communities from management of these invasive mammals in New Zealand forest systems. The present study examined the response of land snail communities to intensive management of ship and Norway rats by sampling paired rainforest blocks, one block of which had been subject to intensive management of rats, while the other block had been without management of invasive rats and thus subject to ambient rodent infestations.
In New Zealand, aerial poisoning with 1080 (sodium fluoroacetate) bait is widely used for control of introduced small mammal pests in remote or forested areas. However this practice is controversial, partly because of perceived risks to native fauna, particularly birds. That perception originally derives from substantial mortality of some native bird species in pre-1980 control operations, which prompted changes in baiting practice to mitigate most of the risk.
Invasive rats can be capable swimmers, able to cross substantial water channels of hundreds of metres to colonise islands. This dispersal capability puts at risk islands close enough to infested areas for rats to reach unassisted. When reinvasion rates are high, biosecurity surveillance on islands might be supported by source population control to prevent re-establishment. However, biosecurity surveillance can only detect reinvading rats when they arrive and the source of reinvading rats might remain unknown.
One of the criteria for an effective bird repellent in a pest management context in New Zealand is that possum (Trichosurus vulpecula) and ship rat (Rattus rattus) kills remain high where repellents are used in poison baits. Repellents were used in baits applied within different treatment blocks as part of a large aerial 1080 operation in November 2013 near Haast on the West Coast of the South Island of New Zealand.
Aerial poisoning with cereal bait containing 1080 toxin is known to pose a risk to the kea (Nestor notabilis), an endemic New Zealand mountain parrot. For a bird repellent to protect kea during such poisoning operations, it must be effective in bait for 4–12 weeks after the bait is manufactured, as this is when most aerial 1080 cereal operations take place. Two bird repellents have been shown to be effective with captive kea, d-pulegone and 9,10-anthraquinone.
Substantial areas of alpine tall tussock grasslands are being retired from grazing as part of Crown pastoral lease tenure review because of the perceived negative impact of grazing livestock. However, relatively little is known about the effect of sheep exclusion on these grasslands. We analysed data from five grazing exclosure plots over a 6-year period to examine the effect merino sheep have relative to hares and rabbits in alpine tall tussock grasslands used for summer grazing.