The intermediate disturbance hypothesis has been the focus of considerable analysis in terrestrial and aquatic systems. This model predicts that species diversity will be highest at intermediate frequencies of disturbance. Despite numerous theoretical and empirical analyses, the utility of the model is still the subject of intense debate.
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 relationship between fleshy-fruited indigenous species and adventive weeds in the diet of 500 mist-netted birds was studied in forest remnants of differing size and degree of modification. Fruit abundance Peaked in March and April, and most fruit was either red/orange or purple/black. The physical parameters of adventive and indigenous fruits were not significantly different. Six of the 15 passerine species netted are frugivores, and of those netted 77% had eaten fruit.
Historical and recent records indicate that kiwi are less numerous and widespread in Hawke's Bay than they used to be. The birds are still scattered throughout the ranges to the west and north of the region, usually at densities of about one bird per 100 ha. Kiwi have now almost completely disappeared from their former lowland habitats. The decline of kiwi in Hawke's Bay may have started before European settlement, but has been particularly rapid in the last 70 years. RePeat surveys of three populations between 1984 and 1990-91 indicate that the decline is continuing.
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.
Species-rich moth faunas at two sites in a montane tussock grassland at Cass show major declines in the abundance of many common species between 1961-63 and 1987-89, furthering a 50- to 70-year trend. The recent faunal record (202 species) is quantified by a 3-point light-trapping methodology based on independence of serial samples, minimised sample variability and a posteriori data standardisation. An historical record of vegetation change is also presented, pointing to a major decline in endemic herb species with the advances of an adventive grass, Agrostis capillaris.
The distribution and abundance of Hochstetter's frog (Leiopelma hochstetteri Fitzinger) in part of the catchment of the Motu River was assessed during two short surveys in 1981 and 1983. Specimens were found in most tributaries examined and on the banks of the main river, above extreme flood level. Crude indices of abundance were obtained by relating the numbers found to the time spent searching and number of stones and logs turned. Generally about four frogs were found per hour, but there was considerable variation in counts obtained in simultaneous searches by different observers.
We evaluated the accuracy and precision of three population estimation methods (mark–resight, distance sampling and five-minute bird counts) for two populations of South Island robin (Petroica australis australis) of known size in the Eglinton Valley, Fiordland, over 5 years (March and August, 2005–2009). The performance of these population estimators was compared to known robin abundance derived from simultaneous territory mapping of individually marked birds.
Robust monitoring systems are required to improve the ecological outcomes of management actions aimed at preventing biodiversity loss. We present a pilot study that measured assemblages of widespread and common bird species at the national scale in New Zealand. Bird surveys were undertaken at 18 sampling locations (six per land cover class: forest, shrubland and non-woody) randomly selected from a national grid. The full sampling protocol (five count stations surveyed on each of two consecutive days) was implemented at 80% of sampling locations.
The New Zealand Garden Bird Survey started in 2007 primarily to monitor long-term trends in common garden bird populations. The method was based on the Big Garden Birdwatch in the UK. Volunteers spent one hour in midwinter each year recording for each bird species the largest number of individuals detected at any one time in their gardens, as an index of abundance. A large number of species was recorded, the two most numerous being house sparrow (Passer domesticus) and silvereye (Zosterops lateralis).
