dispersal

The measurement of parasitism rates of wasp nests;lt Pelorus Bridge, New Zealand, at different distances from the initial release point suggests that the mean displacement of the parasitoid has increased by 1—1.5 km y(-1) from 1988 to 1993. Since average parasitism rates within this radius at any given site show little trend over time, this suggests an approximate 3-fold increase in the total parasitoid population each year, two-thirds of which is devoted to dispersal and one-third to maintaining local populations.

A 20-year capture-recapture study of alpine grasshoppers spanned three distinct sequences of abundance, featuring in turn dis-equilibrium, equilibrium and secondary cyclic equilibrium. This succession of population patterns in the most abundant species, Paprides nitidus, retained high stability between generations. It arose via superimposed life- cycle pathways and adaptive responses between grasshopper phenologies and their environmental constraints.

Records of official deer control operations in the Kaweka Range between 1958 and 1988 have been used to describe the pattern of official hunting, to indicate changes in hunting efficiency, and to show trends in the proportions of sika and red deer in sympatric populations. The pattern of hunting largely reflected wild animal control priorities, and to some extent the resources available.

Twenty-three kiwi were radio-tracked for 16-116 weeks in a Northland reserve. Eighty-three percent of the kiwi made use of the numerous forest remnants scattered over farmland outside the reserve. All remnants isolated by up to 80 m of pasture were used by kiwi. The maximum distance kiwi walked between forest remnants was 330 m. Longer migrations of up to 1.2 km from the reserve were made by kiwi using small forest remnants as 'stepping stones'.

The available literature on ragwort is reviewed. The ecological behaviour of ragwort can be explained by its tendency to act as a colonising plant, which is encouraged by pasture disturbance. Ragwort-infested pasture and closed pasture alternate with each other, and this is influenced by a number of environmental and management factors.

The breeding ranges of thar are described as they were in 1976 and 1984 and compared with previously described ranges in 1936, 1946, 1956 and 1966. Commercial hunting during 1972-1976 harvested about 32000 thar and along with habitat limits in some areas this slowed the rate of dispersal into new areas and eliminated thar from the periphery of their range in other areas. The rate of thar dispersal from the time of their liberation in 1904 until 1936 was non-linear and recalculation of their breeding ranges from 1936-1966 shows rates of dispersal consistent with an exponential curve.

Adele (87 ha) and Fisherman (3.6 ha) Islands lie 800 m and 1100 m, respectively, offshore in Tasman Bay, Nelson. Both are covered predominantly in native forest and scrub. There are mice (Mus musculus) on Adele Island but no rodents on Fisherman Island. Both islands are within swimming range of stoats (Mustela erminea) which have colonised Adele Island and occasionally visit Fisherman Island, 700 m distant.

Tiritiri Matangi Island (‘Tiri’) in the Hauraki Gulf of the northern North Island of New Zealand was deforested, pastorally farmed, and then farming was abandoned in 1972. This history is typical of many northern New Zealand islands. The island’s modern history is less typical; since 1984 it has been the focus of a major restoration project involving thousands of volunteers. No original forest remains, but grazed secondary forest in a few valley bottoms covered about 20% of the island when farming was abandoned. Tiri’s wild vascular flora was recorded in the 1900s and again in the 1970s.

Mortality and/or dispersal immediately after release can cause translocated populations to fail over both the short and long term, particularly at mainland sanctuaries. However, post-release mortality and dispersal can be limited by releasing individuals with an increased probability of survival and site attachment. We monitored a South Island saddleback (tieke; Philesturnus carunculatus carunculatus) population, translocated to a mainland sanctuary, for one year after release to understand the combined influence of post-release mortality and dispersal on initial establishment.

The introduced brushtail possum (Trichosurus vulpecula) is a major environmental and agricultural pest in New Zealand but little information is available on the ecology of possums in drylands, which cover c. 19% of the country. Here, we describe a temporal snapshot of the diet and feeding preferences of possums in a dryland habitat in New Zealand's South Island, as well as movement patterns and survival rates. We also briefly explore spatial patterns in capture rates. We trapped 279 possums at an average capture rate of 9 possums per 100 trap nights.