Research Article

Sika deer (Cervus nippon) were introduced into the central North Island, New Zealand, in the early 1900s. They rapidly established, increased in numbers, and extended their geographic range, eventually displacing sympatric red deer (Cervus elaphus). Sika deer are an important game species, but they can also severely damage native forest, especially where they occur at high densities. Here, we provide the first comprehensive assessment of annual and seasonal home range and movement ecology of adult male and adult female sika deer in New Zealand.

Ecological restoration to mitigate human impacts on the environment is increasingly widespread, particularly in forest ecosystems. Exotic plantation forests have been posited as beneficial for the restoration of forest ecosystems by creating a favourable microclimate in the understorey for native vegetation to establish. Native seed dispersal into plantation forests is a vital part of this process.

Using a sequential adaptive experimental design, we successfully demonstrate that a passive eDNA detection field tool, consisting of pear-baited alkathene pipes equipped with Dacron filters for eDNA capture, can effectively monitor occupancy by a cryptic Otago skink (Oligosoma otagense) population. Detection rates using our eDNA tool were approximately 30–50% higher than those recorded by field teams historically in the Awa Nohoaka Conservation Area.

In New Zealand, predation on endemic biota by house mice (Mus musculus) is a pressing conservation issue. While rodenticides are commonly used, efficacy and bioaccumulation are a concern. Cholecalciferol (vitamin D) offers a reduced risk of bioaccumulation. Our 14-month field study assessed the effectiveness of cholecalciferol-laced bait, which reduced mouse density by up to 59% from peak levels, yet was insufficient for sustained suppression of mice to the low levels required for conservation management.

New Zealand’s native birds are particularly vulnerable to predation from introduced mammals, especially rodents and mustelids. The prolific seeding of trees during mast years triggers rodent irruptions, and the subsequent increase in mustelids can have devastating effects on native bird populations. Waitutu Forest, in Fiordland, New Zealand, has experienced declines in many of its bird populations and has been subject to pest management since 2008 to reverse these trends. A monitoring programme was established to determine the success of this management.

In an area targeted for predator control, untrapped land can act as a source of new predator recruits into the trapped area, reducing biodiversity outcomes. We investigated how increasing the size of untrapped land could drive up costs and also compromise the ability to control predators. Using an individual-based simulation model, we explored how increasing the size of untrapped land impacted rat, possum, and stoat densities and how monetary costs rise because of the need for extra trapping effort near the perimeter of the untrapped property.

In New Zealand, the Nationally Endangered kea (Nestor notabilis) is a large endemic parrot susceptible to non-target mortality from 1080 (sodium fluoroacetate) which is used to control introduced mammals that threaten native biodiversity and livestock. Across all 1080 operations monitored since 2008, mean kea mortality is estimated to be 13%. Public concern around kea by-kill remains high and, consequently, significant effort is directed towards mitigating 1080 risk.

Coastal seabirds are valuable indicators of ecological change in nearshore marine systems impacted by human activities. This study examined how human population growth and urban expansion have influenced the long-term dietary patterns of karoro (southern black-backed gull Larus dominicanus) in Auckland, Aotearoa | New Zealand. Specifically, we assessed whether increasing urbanisation has led to a dietary shift from marine-based prey to greater reliance on terrestrial and anthropogenic food sources.

Studying the effects of inbreeding in wild avian populations can be challenging due to attendant concerns and restrictions when working with endangered species. Therefore, naturally inbreeding species listed as Not of Concern, such as the communally breeding pūkeko (Porphyrio melanotus melanotus, family Rallidae), may provide an excellent model for experimental analyses of inbreeding. We hope that this work will eventually inform conservation efforts directed at endangered species.