Little is known about the movement of stoats in alpine grassland, where several species of native birds, reptiles and invertebrates are potentially at risk from predation. Radio-tracking, live trapping and tracking tunnel techniques were used to sample stoats in two adjacent habitats to determine whether the home range of stoats in beech forest valley floors extends into neighbouring alpine grasslands in the Ettrick Burn Valley, Fiordland.
The sex ratio of the kaka population inhabiting the Waihaha Ecological Area, Pureora Forest Park was estimated between late October 1994 and January 1995. The observed sex ratio estimate was three males to one female compared to a capture rate (using mist nets) of six to one in the same area between January and June 1994. Females appeared to be less susceptible to capture than males. The skewed sex ratio toward male kaka was significant and suggests that female kaka suffer higher mortality (probably due to predation at the nest) than males.
This radio-tracking study reports the daily activity rhythms in autumn and spring of 11 stoats (Mustela erminea) (9 male, 2 female), 20 ferrets (M.furo) (8 m, 12 f) and 11 feral house cats (Felis catus) (7 m, 4 f) resident on coastal grassland, Otago Peninsula, New Zealand. Activity rhythms differed markedly amongst individual stoats in autumn, but little amongst individual cats and ferrets in either season. Stoats were equally active day and night in autumn, but were more active at day than at night in spring.
Home range dimensions and habitat use by ship rats (Rattus rattus) at Puketi, a kauri (Agathis australis) forest in Northland, were examined by live capture and radio-tracking over five weeks in September and October 1993. Home ranges of six females and five males averaged 0.86 ha in area and 174 m in length, with no significant difference in range area or length between males and females. There was substantial overlap in ranges between and within sexes.
Home range and diet of stoats inhabiting beech forest were examined by trapping and radio-tracking. Eleven stoats (6 female, 5 male) were fitted with radio-transmitters. Minimum home ranges of five females averaged 124 ± 21 ha and of four males 206 ± 73 ha. Range lengths of females averaged 2.3 ± 0.3 km and of males 4.0 ± 0.9 km. These differences were not statistically significant. Adult female stoats appeared to have mutually exclusive home ranges. Two females and one male had home ranges that were bisected by the Eglinton River.
Twelve kiwis were radio-tagged and tracked for 12-78 weeks in two sites in Hawke's Bay. Four bonded pairs had ranges of 19.1 to 42.3 ha (estimated by the convex polygon method), which were apparently defended against other kiwis. Two unmated females had ranges of 48.0 and 43.1 ha. Another unmated female occupied a narrow, circular strip, 5.4 km long, covering about 26 ha. The ranges of four kiwis in scrubland and eight in climax beech/podocarp forest were similar in size.
The den use of possums (Trichosurus vulpecula) may be density dependent, meaning that individuals change their denning behaviour in response to changes in population density. Increases in den use due to changes in density may result in increases in bovine tuberculosis (Mycobacterium bovis; bTB) transmission among possums, as infection has previously been correlated with den use. In this study, the den use of a possum population was monitored in 2011 before and after a density reduction event. Females increased their den use following density reduction, but males did not.
The presence of feral cats (Felis catus) in the braided river valleys of New Zealand poses a threat to native species such as the critically endangered black stilt (Himantopus novaezelandiae). Trapping remains the most common method to control introduced predators, but trap placement criteria have not been fully informed by advances in the understanding of the spatial ecology of the pest species. We assessed the suitability of Global Positioning System (GPS) tags to study the spatial behaviour of feral cats in New Zealand braided rivers.