Thirty-one North Island weka (Gallirallus australis greyi) were released on Pakatoa Island (26 ha), Hauraki Gulf, New Zealand in Aug 1996. The population then fluctuated between c.19 and 182 individuals, including c.6-55 pairs. The last of the translocated weka died between Jan and Jun 1998, during a drought and after the rodenticide Talon® was laid to kill Norway rats (Rattus norvegicus), and only weka <1 year old survived. Most young raised in Dec 2001-Jan 2002 died during a drought in Feb – Mar 2002. The weka population increased during a period of higher rainfall from mid-1998 to Dec 2001. The higher population resulted in smaller home ranges, higher frequencies of diurnal spacing calls, more aggressive behaviour, and a higher incidence of plumage damage. The large fluctuations in population size on Pakatoa I suggests that future translocations of weka should select islands with wetter and less variable rainfall patterns.
Few places have been as ecologically devastated by the introduction of exotic mammals as Phillip Island in the Norfolk Island group. Pigs (Sus scrofa), goats (Capra hircus) and rabbits (Oryctolagus cuniculus) denuded the island so severely that massive amounts of soil and underlying substrate were lost through erosion. Rabbits, the last of these exotic animals to be removed, were eradicated during the 1980’s. Since then the extent of vegetation on the island has been increasing by natural revegetation and through plantings and seeding. Fourteen species of seabird currently breed on Phillip Island. Five species—Providence petrel (Pterodroma solandri), Kermadec petrel (P. neglecta), white-naped petrel (P. cervicalis), flesh-footed shearwater (Puffinus carneipes) and red-tailed tropicbird (Phaethon rubricauda)—all have ecologically significant populations. In this paper, we review the current status of the seabird populations breeding on Phillip Island, and suggest how vegetation restoration is likely to affect each species. We update previously published notes and present unpublished material collected by us over more than 3 decades. We document when each species was first discovered, reveal the location of nesting sites, describe breeding phenology and nesting habitat, report on any banding activities and returns, and discuss potential threats.
Conservation management of threatened species (single-species management) is likely to confer benefits to non-target native species, although there are few studies. We examined the relationship between the relative abundance of New Zealand pigeon/kereru (Hemiphaga novaeseelandiae), tui (Prosthemadera novaeseelandiae), grey warbler (Gerygone igata), fantail (Rhipidura fuliginosa) and tomtit (Petroica macrocephala), and intensity of mammalian pest control conducted to protect the endangered North Island kokako (Callaeas cinerea wilsoni) in the Hunua Ranges, 40 km south-east of Auckland, New Zealand. Study areas were subjected to either high intensity (Kokako Management Area, KMA) or low intensity (Milne Stream and Rata Ridge) pest control, and we established 17 monitoring stations per study area and conducted 17 x 5-minute point counts of forest birds in all 3 areas. Abundances of kereru, tui, tomtit, were significantly higher in the KMA. Our findings suggest that single-species management targeted at kokako also benefits some non-target native birds. The contribution of single species conservation management to overall ecosystem integrity is not well understood, and further research is needed to improve the ecological value and cost effectiveness of such management techniques.
Bird nests often contain objects produced and manipulated by other animals, including human rubbish. The function, if any, of these items remains unclear, and it is unknown whether they might serve a signalling role to increase the conspicuousness of the nest lining or contribute to its crypsis. We located several nests of the introduced song thrush (Turdus philomelos) in New Zealand containing discarded cigarette butts. These items were embedded into the dried mud-matrix of the nest and appeared visually inconspicuous to the human observer. However, human and avian visual sensitivities are dramatically different. We used full-spectrum reflectance spectrophotometry, combined with perceptual modelling of the avian visual system to assess the contrast between mud lining, garbage, and the colours of thrush eggs. Our analyses confirmed that, when perceived by birds, cigarette butts were similar in appearance to the nest lining and showed sharp contrast with the eggs. We suggest that cigarette butts form an opportunistic structural component of the song thrush nest. It remains to be determined whether human-made objects in song thrush nests serve anti-predator or an olfactory signalling function. This study illustrates the application of avian perceptual modelling to test signalling based hypotheses for the extended phenotype of birds, including nest architecture.
A total of 57 reef herons (Ardea sacra) were counted during a survey of the entire 1,500 km coastline of the Marlborough Sounds in spring 2006. Most birds were encountered in the outer part of the sounds rather than the more developed inner sounds. The total New Zealand population is estimated at 300-500 birds. Both the Marlborough Sounds and national population appears to have been stable for the past 40 years. With a small but stable population the reef heron’s threat classification in New Zealand should be changed from Nationally Vulnerable to Naturally Uncommon. The species is secure overseas with New Zealand being the southernmost limit for the species.
A survey of the entire 1,500 km coastline of the Marlborough Sounds between Sep – Dec 2006 located 9 king shag (Leucocarbo carunculatus) breeding colonies, including 2 new colonies. The total population was estimated at 687 birds, a figure similar to the 10-year average estimated for the period 1992-2002. The 4 largest colonies supported 85% of all birds recorded. The total population appears stable compared to earlier surveys, but there was a tendency for some of the smaller breeding colonies to be occupied only temporarily.
Using GPS technology, we tracked 3 juvenile northern royal albatrosses (Diomedea sanfordi) as they fledged from Taiaroa Head, Otago Peninsula, New Zealand. All birds flew north along the east coast of New Zealand before undertaking a trans-Pacific easterly migration to Chile. During their 8500 km migration, the maximum daily distance and speed reached were 1047 km and 110 km h-1, respectively, and the maximum altitude was 38 m a.s.l. Upon leaving New Zealand waters, the 3 albatrosses took between 16 to 34 days to reach the coast of Chile where they remained between 23°S and 58°S. The tracked albatrosses generally kept to within 100 km of the coast where the depth of water varied between 1000 and 2000 m. Overall, the tracked albatrosses on the Chilean coast spent 72% of the time resting on the water, primarily between 1800 h and 2400 h local time. Fix success rate of the GPS technology ranged from 56% to 85%. The use of solar charging and a long attachment period allowed birds to be followed continuously for 134 to 362 days. Our study confirms the value of GPS technology in uncovering the movements and life history of wide-ranging oceanic birds.
An appraisal of the conservation status of the post-1800 New Zealand avifauna is presented. The list comprises 428 taxa in the following categories: ‘Extinct’ 20, ‘Threatened’ 77 (comprising 24 ‘Nationally Critical’, 15 ‘Nationally Endangered’, 38 ‘Nationally Vulnerable’), ‘At Risk’ 93 (comprising 18 ‘Declining’, 10 ‘Recovering’, 17 ‘Relict’, 48 ‘Naturally Uncommon’), ‘Not Threatened’ (native and resident) 36, ‘Coloniser’ 8, ‘Migrant’ 27, ‘Vagrant’ 130, and ‘Introduced and Naturalised’ 36. One species was assessed as ‘Data Deficient’. The list uses the New Zealand Threat Classification System, which provides greater resolution of naturally uncommon taxa typical of insular environments than the IUCN threat ranking system. New Zealand taxa are here ranked at subspecies level, and in some cases population level, when populations are judged to be potentially taxonomically distinct on the basis of genetic data or morphological observations. In contrast, IUCN and BirdLife International bird threat rankings are assigned only at species level. This paper represents the first time that the entire modern New Zealand avifauna has been assessed from a conservation perspective. A brief analysis of patterns of extinction, threat, and rarity exhibited by the taxa listed is presented.
Pterodroma occulta was described by Imber and Tennyson in 2001 and tentatively named Vanuatu petrel. The first specimens of this bird were collected in Jan 1927, east of the island Mere Lava in Vanuatu (then New Hebrides), but their breeding grounds have remained unknown. After several exploratory visits to the Banks Islands I discovered a breeding colony of Vanuatu petrels on Vanua Lava in Feb 2009. Statements that this species breeds on Mere Lava were not substantiated.
The New Zealand storm-petrel Pealeornis maoriana Mathews, 1932 was described from 3 specimens collected in the 19th century. Since 1952 it has most commonly been considered a subspecies of Wilson’s storm-petrel Oceanites oceanicus exhibiting the ventrally streaked “Pealea” phenomenon. There had been no recorded sightings of the New Zealand storm-petrel in over 170 years before Jan 2003. Since then, observations off northern New Zealand of storm petrels believed to be this taxon have been made regularly during the austral summer. From observations and photographs, these birds appeared more similar to the New Zealand storm-petrel than to other storm petrel species occurring in the region. However, confirmation of their identity was not possible without capture. In Nov 2005 one was captured off Little Barrier Is, and 3 more were caught elsewhere in the Hauraki Gulf in Jan 2006. Analyses of detailed descriptions, photographs, and morphometric data of these birds provide conclusive evidence that they represent an extant population of the New Zealand storm-petrel. Our analyses of these data and comparison with the New Zealand storm-petrel museum specimens and 17 other Southern Hemisphere storm petrel taxa (subfamily Oceanitinae), lead us to conclude that this species is distinct.