Endemic biota of native grasslands commonly co-exist with introduced grazing mammals, and often this is seen as a conservation threat. The endangered pygmy bluetongue lizard (Tiliqua adelaidensis) is restricted to remnants of native grassland in the mid-north of South Australia, with a long history of sheep grazing. Pygmy bluetongue lizards use ambush predation from their burrow entrances, and prey capture may be more efficient in a habitat with low vegetation density. We experimentally investigated changes in predatory behaviour in this lizard, with different grass density.
The negative effects of introduced nest predators on the breeding success of endemic New Zealand parrots are well documented, as is their role in the general decline of these species. In contrast, little is known about the intrinsic intra-brood dynamics responsible for modulating fledging success in parrots breeding at sites free of introduced nest predators. We studied red-crowned parakeets over two breeding seasons on Tiritiri Matangi, an offshore island free of introduced mammalian predators.
In 1995 and 1996, release of 51 hihi (stitchbird, Notiomystis cincta) onto Tiritiri Matangi Island (wild caught on Hauturu, Little Barrier Island) marked the start of a research and ecological restoration success story. Although establishment of populations of hihi elsewhere in New Zealand has proven to be difficult, the population on Tiritiri Matangi Island has grown to c. 150 individuals and has become one of New Zealand’s few detailed case-study species.
Ongoing investigations into bird mortality caused by aerial 1080 poison operations to suppress pest populations will be required because the operational specifications continually change and improve. We summarise recent studies of bird deaths following 1080 operations and present six principles for use in prioritising future research into poison risk for bird populations. A decision tree (and supporting flow diagram) shows how the need for new surveys can be evaluated using these principles.
The use of non-destructive and non-invasive monitoring methods is often necessary for species of high conservation status. Developing monitoring methods to maximise numbers of individuals found is important, given that rare species can be difficult to locate. Artificial refuges called ‘weta motels’ have been used for monitoring tree weta (Orthoptera: Anostostomatidae) since 1992, but poor occupancy for Hemideina ricta and H. femorata necessitated an improved design and assessment of placement to encourage tree weta use.
Gravel beaches are discrete, irregularly separated habitats along New Zealand’s coasts. They are one of a diverse range of small, disparate, naturally rare ecosystems that tend to occur in extreme environments, and provide critical habitat for threatened, rare and endemic species. New Zealand’s gravel beaches are threatened by urbanisation, weeds, adjacent agriculture, introduced animals and predicted sea-level rise.
Nectar is an important factor influencing the level and persistence of butterfly populations, but particular sources of nectar may not be optimal for all species. In a farmland context, it is not always clear whether nectar sources used by butterflies are good quality species. They may be used opportunistically in the absence of true preferences, therefore possibly limiting maximal reproduction.
Two conservation tools have been developed over the last 10–15 years for species on the New Zealand mainland that are vulnerable to introduced mammalian predators: landscape-scale predator trapping networks, and eradication of predators within mammal-proof exclosures. We tested whether these tools would allow population growth of critically endangered grand skinks (Oligosoma grande) and Otago skinks (O. otagense) over three years.
Invasive mammalian herbivores (e.g. deer, feral goats and brushtail possums; hereafter ‘herbivores’) are widespread throughout New Zealand and their control is important for conservation. In addition to known biodiversity benefits, it has recently been suggested that herbivore control could lead to measureable carbon gains when aggregated across a large area of conservation land. However, a significant amount of uncertainty exists regarding the potential effects of herbivore control on carbon, and the practicalities of successfully implementing such projects.
Kea (Nestor notabilis), large parrots endemic to hill country areas of the South Island, New Zealand, are subject to anthropogenic lead (Pb) exposure in their environment. Between April 2006 and June 2009 kea were captured in various parts of their range and samples of their blood were taken for blood lead analysis. All kea (n = 88) had been exposed to lead, with a range in blood lead concentrations of 0.014 – 16.55 ìmol L–1 (mean ± SE, 1.11 – 0.220 ìmol L–1). A retrospective analysis of necropsy reports from 30 kea was also carried out.