Declines in native birds in New Zealand have raised questions about whether seed dispersal limits plant regeneration and whether introduced mammals such as brushtail possums (Trichosurus vulpecula) can replace absent native birds. We determined the relative contribution to seed dispersal by birds and possums in native secondary forest at Kowhai Bush, Kaikoura. The number of seeds dispersed per hectare per day by each animal species was determined based on the number of seeds per faecal pellet, the number of faecal pellets per animal per day, and the density of animals per hectare.
The New Zealand avifauna has declined from human impacts, which might leave some larger-seeded native plants vulnerable to dispersal failure. We studied fruit dispersal in a lowland secondary forest near Kaikoura, where the only remaining native frugivores are relatively small (silvereye Zosterops lateralis, and bellbird Anthornis melanura). We tested whether two larger exotic frugivores (blackbird Turdus merula and song thrush T. philomelos) dispersed native plants with seeds too large for the two smaller native frugivores.
Fruit-eating animals play a key role in spreading non-native environmental weeds, via seed ingestion and subsequent dispersal. We reviewed available information on dispersal of fleshy-fruited environmental weeds in New Zealand. We found almost a third (32.9%) of 295 environmental weed species in New Zealand have fleshy fruits adapted for internal dispersal by animals. Fruiting phenology differs between weeds and native plants, with many weed species fruiting from late autumn until early spring (May to September) when native fruits are scarce.
The New Zealand mountain flora is rich in fleshy-fruited species but many terrestrial frugivorous birds are extinct or declining, potentially putting seed dispersal mutualisms at risk. To determine whether fruits are currently being removed by animals, we measured removal rates of eight fleshy-fruited mountain plant species from five families over two fruiting seasons, at two sites in inland Canterbury. We compared fruit removal rates within cages (no animal access to fruits), on unmanipulated plants (open-access to fruits by all animals), and within lizard-only cages (large mesh).
This study examined how forest edges, fruit display size, and fruit colour influenced rates of seed dispersal in an endemic, bird-dispersed, New Zealand mistletoe species, Alepis flavida. To examine rates of seed dispersal, fruit removal rates were compared between plants growing on forest edges and in forest interior, and also between two morphs of plants with different coloured fruits. Two aspects of fruit display size were examined: plant size and the neighbourhood of conspecific plants.
Introduced rodents and possums in New Zealand eat flowers, fruits, seeds and seedlings, but little is known about their impact on forest regeneration. We investigated seedling establishment in exclosures with mesh of two different sizes to exclude (1) possums and (2) possums and rats, at two mainland forest sites (beechpodocarpbroadleaved and second-growth broadleavedpodocarp) near Dunedin. We recorded all new woody seedlings that established over the next 2 years.
Recent work at several central South Island sites has shown that the bird-pollinated mistletoe Peraxilla tetrapetala (Loranthaceae) is extensively pollen-limited. We studied the diet, time-budget, and densities of its principal pollinator, bellbirds (Anthornis melanura, Meliphagidae), at Craigieburn to find out what aspect of bellbird ecology may be limiting pollination.
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.
The dispersal, germination and establishment of the New Zealand Loranthaceae (Alepis flavida, Peraxilla colensoi, P. tetrapetala, Ileostylus micranthus and Tupeia antarctica) were investigated. The most important bird dispersers were tui, bellbirds and silvereyes. These birds appear to provide reasonably good quality dispersal: fruits were swallowed whole and the seeds later defecated in germinable condition; birds tended to visit plants for only 1-2 minutes and eat a few mistletoe fruits each time.
Habitat use of a forest bird community was studied in temperate rainforests in South Westland, New Zealand between 1983 and 1985. This paper examines foraging methods, feeding stations and seasonal variations in the availability and use of food types and provides a brief review of the subject. The forest bird community was comprised of a large number of apparently generalist feeders and few dietary specialists. However, the degree of foraging specialisation should not be viewed only in relation to the food types consumed.