Tree-cavity nesting is common for a broad range of bird species throughout the world. However, the majority of information on the use of cavity nests is largely derived from the Northern Hemisphere with little data originating from tropical or southern temperate areas. We discuss 3 factors (predation, microclimate, and cavity abundance) that may have shaped the evolution of New Zealand’s tree-cavity nesting birds. New Zealand’s landbird fauna possesses the highest percentage (24%) of secondary tree-cavity nesters (7 orders and 12 families) of any region examined. Given the high occurrence of tree-cavity nesting in New Zealand’s avifauna there may be environmental pressures that select for this form of nesting. Historically, birds were likely the main nest predators of New Zealand’s cavity nesting birds and indications are that nest predation levels are not comparable to some continental habitats. This suggests that other factors such as microclimate or cavity abundance may have played a disproportionate or complementary role in influencing the high percentage of tree-cavity nesting in New Zealand. However, evidence is limited and any attempt to identify selection pressures on tree-cavity nesting must be balanced against phylogenetic concerns, as some birds were likely tree-cavity nesters before their arrival in New Zealand.
New bioacoustic technologies offer novel ways to monitor bird populations in the field. Bioacoustic techniques can greatly enhance effective field time, enhance survey site coverage, and increase quantification of key time periods such as crepuscular and nocturnal hours. Moreover, digital files provide searchable, independently verifiable records. Historical impediments to the use of bioacoustics have diminished with unit costs declining and data storage capacities increasing. Recent software developments enable rapid extraction of targeted bird calls and facilitate ease of data analysis. This paper details the recent application of bioacoustic technology at a proposed wind farm site in the upper North I, New Zealand. In this case, bioacoustics were employed as a supplement to on-site field observations and as a complement to avian radar technology. Results illustrate the utility of bioacoustic methods, highlighting the range and scale of potential data outputs. In addition to the detection of flight calls and song, audible wing flap noise may provide a further means of identification for some species. Targeted monitoring of migrant birds, cryptic marshbirds, and rare seabirds are identified as potential future applications.
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.
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.
In a 5 year radiotracking study of 55 falcons on the Wairau Plain, Marlborough, the causes of death in 21 birds were identified. Of these, 10 (47%) falcons were electrocuted (7 juvenile females, 1 adult female, 1 juvenile male, and 1 adult male). Seven of the 10 poles were fitted with transformers. This level of mortality is thought to be too high to sustain a population of falcons. Suggestions are made how to mitigate the problem.
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.
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.