abundance

The Hochstetter’s frog (Leiopelma hochstetteri) is a nationally At Risk – Declining species, but management decisions for this species are limited by the lack of established monitoring protocols and analytical methods. We compared methods for inferring spatial and temporal patterns in abundance on Aotea (Great Barrier Island) using count data collected from fifteen 100 m stream transects in 2012, 2015 and 2021. Each transect was surveyed 2–3 times on the same day each year.

Habitat disturbance is a significant factor contributing to biodiversity decline worldwide. Amphibians are particularly vulnerable because of their specific microclimatic and microhabitat requirements. In Aotearoa New Zealand, Archey’s frogs (Leiopelma archeyi) have shown some degree of resilience to severe habitat disturbance historically. However, it is unknown how much L. archeyi populations are currently being impacted by historical and ongoing mining activities and development within their range.

New Zealand (NZ) is an internationally significant area for penguins. All NZ penguin species are listed in ‘at risk’ threat categories. The naturally uncommon Snares crested penguins (Eudyptes robustus), which are restricted to NZ subantarctic islands, are highly susceptible to localised stochastic events and human activities. There has been uncertainty about population size and trends for Snares crested penguins.

There are many examples in the literature of a positive correlation between the distribution of a species and its local abundance, i.e., widely occurring species tend to be more abundant locally when they do occur. Such relations have been documented over a wide range of taxa and spatial scales. There are five major hypotheses seeking to explain the relation: Random placement, Sampling error, Niche width, Demography, and Metapopulation dynamics. However, there is little evidence to distinguish between them, especially for plants.

For two summer/autumn periods (1999, 2000), we studied the movements and survival of feral ferrets (Mustela furo L.) at a site in North Canterbury that had been previously subjected to intensive control of ferrets. Movement distances of juvenile ferrets from the place of initial to final capture were generally low (median = 1.2 km) though variable [mean = 2.5 ± 1.0(±S.E.M.), range 0.1-21.7 km]. The estimated instantaneous mortality rate of juvenile ferrets was high (mean = 0.8 per year), though imprecise (95% C.I.

The spatial distribution of feral ferret (Mustela furo) activity and denning were studied using ink-print tracking tunnels and radio-tracking within pastoral farmland containing a mosaic of grazed (developed and semi-developed) and ungrazed pasture, scrub, tree plantation and scrubby fence lines at Palmerston, East Otago, South Island, New Zealand. Ferrets concentrated their activity in grazed areas but within these areas they were found more often where herbs, scrub and woody cover were present, and where there was an ecotone between pasture and vegetation cover.

Stoats were monitored by three methods through an aerial 1080 poisoning operation at Waimanoa, Pureora Forest in August 1997. Tracking rates and number of live captures were used as indices of abundance, and radio-transmitters were used to follow individual animals. All 13 stoats with radio-transmitters within the poisoned area died between 2-18 days after the operation. No mustelids were tracked or live-trapped after the operation for three months. Of the radio-tracked stoats that died, rat remains occurred in 67%, passerine birds in 17%, cave weta in 17% and possum in 8%.

Stoat (Mustela erminea) density was estimated by live-trapping in a South Island Nothofagus forest, New Zealand, at 8-9 (Jan/Feb 1996) and 15-16 (Aug/Sep 1996) month intervals after significant beech seedfall in autumn 1995. Absolute densities were 4.2 stoats per km² (2.9-7.7 stoats per km², 95% confidence intervals) in Jan;Feb 1996 and 2.5 stoats per km² (2.1-3.5 stoats per km²) in Aug/Sep 1996. Trappability of stoats increased in the latter sampling period, probably because mice (Mus musculus) had become extremely scarce.

Changes in Hieracium abundance in Eastern Otago tussock grassland were examined by sampling 163 sites in 1982 and again in 1992. For Hieracium pilosella, H. praealtum and H. lepidulum, as well as Agrostis capillaris for comparison, colonisation of new sites was recorded, as well as extinction of species from sites over the 10 years, and changes in cover. H. pilosella colonised the majority of sites from which it had been absent in 1982; it disappeared from only a few sites where it had been present at very low cover.

Polistine and vespine wasps were captured in Malaise traps in two fire-modified shrubland habitats of varying canopy height and composition at Lake Ohia, Northland, New Zealand. Prey consumption rates were calculated for the Asian paper wasp (Polistes chinensis antennalis) occupying these two areas of shrubland and a home garden in Whangarei, Northland. The sites were systematically searched for nests and wasp prey determined by intercepting foragers returning to nests.