Five-minute bird counts in Pureora Forest Park were compared between one site in a 1978-81 study and two similar sites in a 1997-98 study. The two sites from the more recent study have had different levels of pest control since the historical survey. The mean number of birds detected per count was calculated for each species and the differences among the sites were tested for significance. The results suggest a dramatic decline over time (irrespective of pest control) in many small native insectivores, including the grey warbler (Gerygone igata), tomtit (Petroica macrocephala), fantail (Rhipidura fuliginosa) and rifleman (Acanthisitta chloris). A large increase in bellbird (Anthornis melanura) conspicuousness was detected. Increases were observed for robin (Petroica australis), kokako (Callaeas cinerea wilsoni), kaka (Nestor meridionalis), parakeet (Cyanoramphus novaezelandiae) and kereru (NZ pigeon Hemiphaga novaeseelandiae) between the historical site and the recent pest-controlled site, but tui (Prosthemadera novaeseelandiae) counts have decreased. The number of species with higher mean counts in the site with more intensive pest treatment suggests that pest control has had a positive effect on some bird populations. However, some species also increased at the site with less-intensive treatment, and tui is more conspicuous at this site than the controlled one. The study shows the value of historical bird count surveys for assessing long-term changes in bird populations, and suggests a need to make similar data sets from around New Zealand more readily available to researchers.
Cook’s petrel (Pterodroma cookii), a New Zealand endemic, now breeds on only three islands at the extremities of its former range. Holocene fossil bones have indicated sites of 11 extinct colonies on North and South Islands, showing that Cook’s petrels preferred hills Gallirallus australis) have endangered these last colonies. Breeding success, most affected by rat predation of eggs and chicks, deteriorated seriously after extermination of feral cats from Hauturu, but improved significantly after eradication of rats from Whenua Hou. Rats are now a major threat on Hauturu. Cook’s petrels should be considered for reintroduction to suitable mainland reserves, to enhance biodiversity and restore nutrient inflows.
The taxonomic status of the endangered orange-fronted parakeet (Cyanoramphus malherbi)) has been the subject of much debate since this endemic New Zealand parakeet was first described in 1857. The debate in the late 1800s and again over the past 30 years has been lively but inconclusive. We provide a summary of this debate and the most recent research into the taxonomic status of this parakeet based on mitochondrial DNA (mtDNA), assortative pairing, bill morphology, vocalisation, and comparative ecology. Based on all available scientific and historical data, we conclude that the orange-fronted parakeet is a distinct species.
Little is known of the causes of mortality in captive-bred brown teal (Anas chlorotis) released to the wild. To test whether feeding difficulties have contributed to the poor survival of released birds, we developed a method to detect starvation using the wing fat content of brown teal. We extracted the lipids from 4 outer wing components of 17 intact brown teal carcasses. The lipid content of each component reflected the birds’ nutritional condition (based on body mass and size, and visible fat). Lipids were also extracted from the outer wing components of 7 partial brown teal carcasses, 6 of which were from captive-bred released birds whose cause of death could not be determined. All of the released teal were found to have been in very poor nutritional condition immediately before death, implicating starvation as a factor in their deaths. Improving the feeding regime of captive-bred brown teal (pre- and post-release) is likely to increase their survival.
Bellbird breeding activity was monitored on Tiritiri Matangi Is in 1977 and 1978. The density of bellbirds breeding within the study area was 2.13 pairs ha-1. Resighting of banded adult birds in consecutive years was 69% and less than half the pair bonds were maintained into the following season. Breeding extended from Oct to Jan, with a peak in Nov. Most nests were built in tree ferns, and the mean clutch size was 3.6 eggs. Incubation and nestling periods were c. 12 and 14 days, respectively. The female bellbird was significantly more active than the male in care of the nestlings. Measurements of chick head and wing length were correlated with age. Nest success was 44%, and daily survival rate 97%. Predation, desertion, and exposure contributed to nest failure, and re-nesting was common. The mean number of nests female–1 season-1 was 1.3, while mean reproductive success was 2 chicks fledged. Young were independent 2 weeks after fledging, and moulted to adult plumage in their 1st year. The dynamics of the Tiritiri Matangi population, when compared with other populations, suggest that breeding behaviour is a flexible response to environmental factors, and will vary between populations depending on the level of predation, competition and habitat quality.
A quantitative survey of the bird community of Kaitoke wetland, Great Barrier Is., New Zealand between May 1998 and July 2000 using 5-minute counts recorded 33 species, most of which occurred in less than 10% of counts. The commonest species were North Island fernbird (Bowdleria punctata), fantail (Rhipidura fuliginosa), silvereye (Zosterops lateralis), grey warbler (Gerygone igata), welcome swallow (Hirundo neoxena) and (collectively) the exotic finches, yellowhammer (Emberiza citrinella), chaffinch (Fringilla coelebs) and goldfinch (Carduelis carduelis). Native wetland species also recorded were spotless crake (Porzana tabuensis), banded rail (Rallus phillipensis), Australasian bittern (Botaurus poiciloptilus), pukeko (Porphyrio melanotus) and Australasian harrier (Circus approximans). Distributional analysis of the commonest species (those occurring in more than 10% of counts) showed most had some association with a particular vegetation type(s), while few showed any change in conspicuousness with season. There was little apparent movement of birds associated with phenology of the main wetland plant species. The significance of Kaitoke wetland in providing habitat for a range of native wetland bird species is recognised. The current threat to this ecosystem from introduced pests and development pressure, and the paucity of data available on native wetland bird species to inform conservation management, is discussed.
The breeding success of northern New Zealand dotterels (Charadrius obscurus aquilonius) on Matakana Island, Bay of Plenty, was determined over 8 seasons (1992/93-1999/2000) in managed and unmanaged areas. Management to enhance breeding success included shifting nests to reduce the risk of flooding during spring tides and storms, and reducing predator populations of brushtail possum (Trichosurus vulpecula), feral house cat (Felis catus), Norway rat (Rattus norvegicus), stoat (Mustela erminea), and southern black-backed gull (Larus dominicanus) at dotterel breeding areas. Measures taken to reduce the incidence of disturbance by people on breeding dotterels included erecting fences around nesting areas, and speaking to members of the public about the plight of the species. The number of breeding pairs on Matakana Island fluctuated between 19 and 31 during the 8 seasons. Overall, 35.1% of 276 nesting attempts resulted in broods hatching. The main causes of nest failure during incubation were flooding by high tides or storms, and predation. The proportion of nests in which 1 or more eggs hatched was fairly stable during the 1993/94 to 1997/98 seasons at 26.1-33.3%, but was 68.0 and 51.3% in the last 2 years. This marked improvement in nesting success was attributed to the increased duration of pest control: starting before dotterel breeding began and continuing until most broods had fledged. Nesting success during incubation in managed habitat (47.5%) was significantly greater than in managed habitat (19.5%). Overall, 52.6% of chicks fledged. The number of chicks fledged per season (5 – 33), and fledglings produced per breeding pair (0.26 – 1.08) increased through the study In conclusion, we make suggestions to further promote the conservation of the northern New Zealand dotterel.
The brown teal (Anas chlorotis) is a threatened duck endemic to New Zealand, whose single remaining stronghold is on Great Barrier Island. During a study at Awana from 1985 to 1987 it was concluded that the population was stable. We evaluated this proposition by analysing counts made at flocking sites between 1985 and 2001, examining their demography, and by developing an age-specific demographic model to predict the likely persistence time of the population. Numbers of teal at flocking sites declined between 1985 and 2001 though demographic variables did not change except for duckling survival rate, which increased from 26% during 1996 to 54% during 1999. Previous predictions of stability were based on an incorrect model and our model suggests that the brown teal population will halve every 4.1 years. The decline observed since 1987 could be halted by improving adult survival rate.