reproduction

Ecology of a brushtail possum (Trichosurus vulpecula) population at Castlepoint in the Wairarapa, New Zealand

Brushtail possums at a 21 ha site at Castlepoint in the Wairarapa, New Zealand, were studied with capture-mark-recapture from August 1989 to August 1994. The mean annual adult population density, based on counts of mature possums trapped each year, was 8.7 per ha and varied by only small amounts during the study period. The median survival age was 32 months (95% CI 28–39) for females and 27 months (95% CI 26–30) for males.

Selection for melanism and for low reproductive rate in Trichosurus vulpecula (Marsupialia).

Agouti grey pelage, as found in the opossum and many other mammals, is a generalised concealing coloration. In dense vegetation melanic pelage also is concealing, but the melanic phase displaces the grey one in rain forests where, in the current absence of predation, selection is not for colour. This local dominance suggests close linkage of genes for melanism with ones for toleration of humidity.

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).

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.

Population biology of small mammals in Pureora forest park .1. Carnivores (Mustela erminea, M. furo, M. nivalis, and Felis catus)

Populations of four species of carnivores were sampled over the five years 1983-87 at Pureora Forest Park, by regular three- monthly Fenn trap index lines supplemented with occasional control campaigns by shooting and additional traps. Stoats were the most frequently collected (63 captures), followed by weasels (18), cats (15) and ferrets (13). Stoats ranged throughout the mosaic of forest types but especially the older exotic blocks, hunting rabbits, rats, possums and birds. The mean age of 55 stoats trapped was 15 months, and their maximum life span about 5 years.

Population-Dynamics and Diet of Rodents on Rangitoto Island, New Zealand, Including the Effect of a 1080 Poison Operation

The objective of this study was to quantify the population dynamics, morphological characteristics, and diet of rodents on Rangitoto Island (Hauraki Gulf, New Zealand) to provide information for the future development of an eradication strategy. An aerial 1080 operation to eradicate possums and wallabies was carried out two months after the study began. The effects of this operation on rodent population dynamics are discussed. Both ship rats (Rattus rattus) and mice (Mus musculus) were trapped on Rangitoto Island over a 15 month period.

The Effects of a Natural Increase in Food-Supply on a Wild Population of House Mice

Changes in density and breeding of the house mouse (Mus musculus) in a New Zealand forest dominated by hard beech (Nothofagus truncata) were monitored for 2.5 years. Mice bred during winter and increased dramatically in density only during a beech mast year. Mice readily ate the endosperm and embryo of hard beech seed in die laboratory and chemical analysis showed it to be a very nutritious food source, similar in quality to Fagus beech seed in the northern hemisphere.

Aspects of the Ecology of Feral Pigs (Sus scrofa) in the Murchison Area, New Zealand

Seven feral pigs (Sus scrofa), radio-tracked in relatively undisturbed rough pasture and forest near Murchison, New Zealand, for periods of 18-186 days, occupied home ranges of 28-209 ha. The immature pigs were significantly more active and had significantly larger home ranges than the adults, particularly adult females. The pigs were mainly nocturnal but they varied individually. The frequency of grazing and the rooting up of pasture and bracken (Pteridium esculentum) varied seasonally.

Brushtail Possums (Trichosurus vulpecula Kerr) in a New Zealand Beech (Nothofagus) Forest

Brushtail possums were studied over a period of four years by live-trapping, poisoning and kill- trapping on an altitudinal transect (455-1500 m a.s.l.) in beech (Nothofagus) forest in South Island, New Zealand. There was a single breeding season in autumn in which most females (including 80% of one-year- olds) panicipated. Trap-revealed ranges of adults were up to 1 km long and some immature males dispersed up to 10 km. Capture rates in live-traps were highest in beech/podocarp forest at 455-460 m a.s.l. and declined with altitude.

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