New Zealand

Assays for the toxin sodium monofluoroacetate (compound 1080) were undertaken on arthropods collected from toxic baits after a brushtail possum (Trichosorus vulpecula) control operation in Nothofagus forest in central North Island, New Zealand. The 1080 concentrations measured (mean 57 mu g per g, max 130 mu g per g) are considerably higher than those reported by other researchers who collected arthropods randomly after control operations.

Hihi (or stitchbird, Notiomystis cincta) is a rare honeyeater endemic to the North Island of New Zealand. Hihi were translocated from Little Barrier Island to Mokoia Island, Lake Rotorua, in 1994. Mokoia is a small (135 ha) island with secondary vegetation, so there was some doubt as to whether the island had sufficient diversity of fruit and nectar sources to support a hihi population. This paper reports data collected in the year after the translocation on the density, distribution and phenology of plants likely to be used by hihi. We address the following questions.

The risks to non-target species of a newly developed bait containing either 0.15% 1080 or 0.6% cholecalciferol in a gel matrix were assessed. Very few of them ate gel bait. The safety of the gel bait is further enhanced by its placement in the purpose-designed bait station from which little spillage occurs, and which can be placed so that it is out of reach of most non-target animals. Comparative data show that nontarget species are considerably less susceptible to cholecalciferol than to sodium monofluoroacetate (1080).

Poisonous baits used for pest control in New Zealand commonly contain green dye and cinnamon oil to make them less attractive to birds. Research aimed at reducing the impact of poison based pest control on birds has shown that some birds are initially deterred from feeding on blue or, to a lesser extent, green coloured food and are attracted to yellow or red food. We determined whether colours that deter or attract birds affected the acceptance of non-toxic and toxic cereal baits by captive brushtail possums (Trichosurus vulpecula).

The field use of brodifacoum baits (Talon(R) and Pestoff(R)) to control brushtail possums (Trichosurus vulpecula) has increased in recent years. This has raised concerns of secondary and tertiary poisoning, resulting from the transfer of this toxicant through the food chain. In New Zealand, feral pigs (Sus scrofa) are known to scavenge possum carcasses and and may also gain access to bait stations containing possum baits. We have determined the concentrations of brodifacoum in muscle and liver tissue from captive pigs after primary and secondary poisoning.

Toxins, especially sodium monofluoroacetate (1080) and brodifacoum, are widely used throughout New Zealand for control of introduced mammals that are considered pests. This level of toxin use (not necessarily with these toxins) is unlikely to decline for at least 5-10 years. Ecological consequences derive both from mammal population reduction or eradication, and from using toxins as the control method.

We analysed biomass allocation of Pleurophyllum speciosum (Asteraceae) and Anisotome latifolia (Apiaceae) to explore the 'megaherb' phenomenon, the apparent importance of large-leaved, colourful forbs on southern oceanic offshore islands. The two species had similar shoot dry weights, with high leaf:stem ratios. Even within the megaherb form there are differences in shoot allocations, with Pleurophyllum investing more biomass in rhizome than foliage, compared with Anisotome.

Insect communities from a range of successional vegetation stages on the central North Island volcanic plateau were characterised and compared using Malaise trapped beetle samples. Results were derived from sampling series conducted in a total of ten sites over three separate summers. Divisive classification successfully grouped samples according to four main habitat types despite temporal and spatial separation of samples within these groups. A four-week period in early summer was found to be optimum for sample discrimination according to the main vegetation types.

Population structure, diversity and gene flow in four populations of Aciphylla glaucescens were studied using allozymes. Six of the seven putative loci were polymorphic in at least one population. Within populations the mean percentage of polymorphic loci was 68%. Gene diversity for Aciphylla glaucescens (H-e = 0.258) was greater at the species level compared with other outcrossing, wind pollinated plant species (H-e = 0.162). The mean diversity among populations of A.

Eradication of rodent species from some offshore islands has proved to be an effective means of conserving native animal communities and restoring natural ecological processes on the islands. As methods of eradication differ fur different rodent species, a truthful monitoring method to detect species presence and relative density is essential for a successful eradication programme.