New Zealand

Generalist entomopathogens as biological indicators of deforestation and agricultural land use impacts on Waikato soils

The relative abundance of entomopathogenic nematodes and fungi was estimated for 10 sites in each of indigenous forest, pasture, and cropland habitats by baiting soil samples with Galleria larvae. The steinernematid Steinernema feltiae (Filip) was the dominant nematode, occurring in soils from all three habitat types. The heterorhabditid Heterorhabditis zelandica Poinar was recovered only from soils of podocarp (Dacrycarpus dacrydioides (A. Rich.)) forests.

Comparison of two techniques for assessing possum (Trichosurus vulpecula) diet from stomach contents

Two techniques for assessing possum (Trichosurus vulpecula Kerr) diet from stomach contents ("point-sampling" and "layer- separation") are described and compared. Point-sampling involves sieving stomach contents, systematically selecting fragments from the retained material then, identifying and weighing these. Layer-separation involves separation, identification, and weighing of the discrete layers apparent in most possum stomach contents. In 41 of 43 stomachs examined, we were able to separate discrete layers that nearly always comprised a single food item.

Space use and denning behaviour of wild ferrets (Mustela furo) and cats (Felis catus)

We monitored the behaviour of 62 radio-collared ferrets and 25 radio-collared cats in dry, tussock grassland habitat in New Zealand's South Island. The total home range of adult male ferrets (102 ± 58 ha, mean ± 1 s.d.) was marginally greater than that of females (76 ± 48 ha), and averaged 90 ± 55 ha. Male ferret core ranges (27 ± 15 ha) were larger than those of females (16 ± 8 ha). Adult cat home ranges were similar between sexes, and were larger and more variable than those of ferrets (225 ± 209 ha). Core range size of cats was similar between sexes and averaged 54 ± 24 ha.

Effect of flowering on vegetative growth and further reproduction in Festuca novae-zelandiae

Flowering intensity and plant size were monitored in 155 Festuca novae-zelandiae individuals over four years to determine if trade-offs exist between inflorescence production and vegetative growth, and between inflorescence production in different years. Less than half of the population flowered in any one year, 36% of individuals did not flower at all, and only 17% flowered in all four years of the study. Mean number of inflorescences per individual per year varied from 1.54 to 5.53 (maximum = 85).

The diet of the North Island kaka (Nestor meridionalis septentrionalis) on Kapiti Island

Food of the North Island kaka (Nestor meridionalis septentrionalis) on Kapiti Island was identified while quantifying the foraging activity of nine radio-tagged birds from March 1991 to January 1992. Additional food types were identified by opportunistic observation of feeding birds and qualitative examination of nestling faeces. A diverse range of food was taken, including wood-boring invertebrates, scale insects, seeds, nectar or pollen, fruits, and sap.

Spider density and diversity in relation to disturbance in agroecosystems in New Zealand, with a comparison to England

Spider assemblages were sampled by quantitative sampling in pasture and arable habitats under different management regimes in the lower North Island of New Zealand. Density and species diversity increased with decreasing frequency and/or intensity of disturbance from two species and 1.8 individuals per m in wheat to 16 species and 130 indiv. per m in an abandoned, ungrazed pasture. The spider fauna was dominated by introduced species of money spiders (Linyphiidae). The most abundant species, Lepthyphantes tenuis, is also the most abundant one in British cultivated habitats.

Population biology of small mammals in Pureora Forest Park .2. The feral house mouse (Mus musculus)

Over five years from November 1982 to November 1987, we examined 395 mice collected from unlogged and logged native forest and from exotic forest at Pureora Forest Park, in the central North Island of New Zealand. Sex ratio, litter size, and breeding effort (pregnancy rate in females, proportion of males with visible tubules) were similar in all samples.

Distribution and abundance of small mammals in relation to habitat in Pureora Forest Park

Populations of ship rats (Rattus rattus), Norway rats (R. norvegicus), feral house mice (Mus musculus), stoats (Mustela erminea), weasels (M. nivalis), and ferrets (M. furo) were sampled with killtraps every three months from November 1982 to November 1987 in logged and unlogged native forest and in exotic plantations of various ages at Pureora Forest Park, central North Island. Mice (n=522 collected) were fewest in unlogged native forest, more abundant in road edge cutover forest, and most abundant in a young (5-10 year old) plantation.

The ecology of Bonamia and decline of bivalve molluscs

Bonamia is a protozoan parasite of the haemocytes of oysters (Tiostrea chilensis), in which it has an annual developmental cycle between November and August each year. The parasite transmits directly, oyster to oyster, and therefore disease spread is related to host stock density. The Foveaux Strait oyster population experiences large mortalities every 20-30 years, and these may be attributable to Bonamia. The parasite appears to become less pathogenic at the end of, and probably between, mass mortalities, and some oysters appear more tolerant of infection than others.

Sudden decline of cabbage tree (Cordyline australis): Search for the cause

Many cabbage trees (Cordyline australis) are dying throughout much of the North Island and the northern South Island of New Zealand. The symptomatology of those dying in urban environments is described, and is concluded to be consistent with the hypothesis that death is caused by a biotic agent entering through a leafy tuft of the branch system. This disease, which has been named Sudden Decline, usually leads to almost total defoliation of affected trees within 2-12 months. Disease incidence has increased linearly at about 11% per annum since 1987/88. Cultivated trees of C.