Publications Archive

Abstract: Life history and ecological characteristics of extant mergansers (Tribe Mergini) are summarised and used to infer those likely displayed by the extinct merganser from “mainland” New Zealand (Mergus sp. indeterm.). I speculate this was a river-dwelling species, plausibly a year-round territorial occupant of mid-lower reaches of rivers, whose subadults and non-breeders may have aggregated seasonally on broad lower reaches, including estuaries. Of extant mergansers, its ecology was probably most similar to that of Brazilian merganser (Mergus octosetaceus). Holocene sea-level rise and loss of habitat may have induced changes in social structure of Chatham Island merganser. A plausible life history and ecological template, however speculative, can aid evaluations arising from other sources of evidence e.g. locations of fossils and bone stable isotope chemistry.

Kororā, little penguin, breed in New Zealand and Australia with two subspecies now recognised after numerous taxonomic revisions: Eudyptula minor minor only in New Zealand, and E.m. novaehollandiae, in Australia and Otago on the southeast coast of South Island, New Zealand. One of the distinguishing features of E.m. novaehollandiae is the possible laying of a subsequent clutch by the same female after successfully fledging chicks (double brooding). In this study in Wellington, North Island, 25–53 nestboxes used for breeding were monitored for 10 years, 2014–2023 to determine abundance and breeding success. From the 380 clutches, 81% of eggs hatched, 87% of hatched chicks fledged, 70% of eggs fledged chicks, and 1.32 chicks fledged per clutch. Micro-chipping of adults from 2021 allowed identification of individuals at most locations. Double brooding was suspected prior to 2021 and was confirmed at one location in 2023. This is the first record of double brooding of kororā on the North Island. Genetic analysis of the female will resolve whether E.m. minor can double brood or if E.m. novaehollandiae has reached the North Island.

Banded rails (Hypotaenidia philippensis) were monitored using footprints before, during, and after the partial removal of 1.8 ha of mangroves (Avicennia marina) from a 2.4 ha area in the Ruakaka estuary. Mangrove removal occurred in two phases: adult trees in winter 2014 and juvenile plants and pneumatophores in winter 2015. Banded rails were only detected on the margins of mangroves during adult tree removal, and then throughout the cleared areas after seedling and pneumatophore removal. In 2016, 2018, and 2020, rails showed a similar use pattern in the uncleared and cleared areas to that used before mangrove removal. After mangrove seedling and pneumatophore removal, potential predators, including cats (Felis catus), were present most of the time, and mustelids (Mustela spp.) were present in summer.

Understanding plant invasions is important in conservation ecology and land management, as invasive plant species worldwide have caused irreparable damage and often incur substantial control costs. To record the dispersal vectors for the invasive barberry (Berberis glaucocarpa) in a New Zealand regenerating forest, video cameras were used to film 24 barberry plants in fruit in Kowhai Bush, Kaikoura. During 242 hours of video, a total of 101 foraging events were recorded by four bird species: silvereye (Zosterops lateralis), blackbird (Turdus merula), song thrush (T. philomelos), and starling (Sturnus vulgaris). The four bird species varied in visitation frequency, time spent on plants, and fruit removal rates. The estimated daily contribution to recorded barberry fruit removal was 42.8% by song thrush, 32.6% by silvereye, 24.3% by blackbird, and 0.2% by starling. No endemic bird species were observed feeding on barberry, despite bellbirds (Anthornis melanura) being common in Kowhai Bush. Removal rates for ripe barberry fruit were relatively modest (1.14% per day), but given the ~3 month fruiting season, represented a sizable seed rain in the surrounding forest. Although barberry is now sympatric with several introduced frugivores in New Zealand, none of its dispersers from its native range in Nepal and northern India are present. Instead, dispersal in New Zealand is facilitated primarily by introduced European bird species and native silvereyes.

The spotted shag (Phalacrocorax punctatus) forages in coastal marine waters up to about 16 kms offshore, and typically nests in rock cavities and on ledges of coastal cliffs. Some shags roosting on the Tata Islands and perhaps at sites nearby in Golden Bay, northern South Island, come near or onshore at Tata Beach at dawn. Counts of these shags were carried out to determine monthly and annual fluctuations in numbers during the 10-year period 2009–2018. Numbers peaked in winter (May–August), the likely non-breeding season of the spotted shag in the northern South Island. Mean numbers per count per year peaked in 2009 (1037 shags), declined up to 2014 (309), and then remained fairly stable through to 2017. It is unknown whether this decline in abundance is the result of fewer spotted shags overwintering in Golden Bay after breeding elsewhere in the northern South Island, or whether the regional population has declined. Future monitoring of the spotted shag, particularly of its abundance and breeding success at colonies, would be useful so that any changes in its conservation status in the upper South Island will become evident.

A collection of 16 birds from Hokianga, including the type specimens of banded rail Hypotaenidia philippensis assimilis and black petrel Procellaria parkinsoni, is recorded as presented to the British Museum in 1842 by a mysterious “Miss Rebecca Stone.” She is identified as Rebecca Stones of London, who presented birds brought from Hokianga by her brother William Stones. A further search for the collector in Hokianga, based on the evidence of the specimens and how they were obtained, prepared and documented, points to the Wesleyan missionary William White, and also reveals much about the practices of ornithology of the time. It also reveals that Hokianga Māori, notably Mohi Tāwhai of Waimā, played a significant role in obtaining and naming birds for the collection. The type localities for New Zealand banded rail, black petrel, and Botaurus melanotus are restricted to Hokianga, Northland.

Understanding the drivers for the seasonal movements of kea at landscape scales is critical to their conservation. Recent developments and increasing use of Global Positioning System (GPS) trackers prompted a small-scale trial on kea (Nestor notabilis) in Aoraki/Mount Cook National Park during October 2021 to February 2022. We attached a solar charged Druid Debut Lego™ tracker to four birds: two nesting females, a juvenile male and a recently fledged male. One tracker, with a raised solar panel, transmitted data by 3G cell phone network and the others sent data by 2G GSM cell phone network. The two trackers with raised solar panels collected and transmitted substantially more data than the flush-mounted solar panels. Location data was mapped, and elevation, distances travelled, 24-hour movement patterns and activity behaviour were analysed. The limitations of these GPS trackers are discussed, and recommendations are made for future use of GPS trackers on kea where topographic shading, power consumption, satellite reception, and data transmission are likely to remain significant challenges.

The Auckland Domain is the city’s oldest park and contains over 70 ha of contiguous, mature urban forest. Five-minute bird counts were made across one year within the domain forest in 2019 and 2020 and compared with counts conducted in 1987 and 1988, using the same methods and at the same survey sites, to investigate changes in the structure of the urban bird community. The abundance and species richness of native and introduced birds increased between the count years and there was structural change within the community driven by increases in the abundance of forest-adapted endemic species, tūī Prosthemadera novaeseelandiae, grey warbler Gerygone igata, and kererū Hemiphaga novaeseelandiae, and declines in generalist native species, silvereye Zosterops lateralis and fantail Rhipidura fuliginosa. Tūī showed the most profound increase in abundance between count years, reflecting regional conservation management of mainland and island forest habitats that benefit this highly mobile species. Increased abundance of eastern rosella Platycercus eximius and common myna Acridotheres tristis also altered community structure between count years, indicative of ongoing colonisation by these exotic species in the Auckland region since their introduction to the North Island. The fact that both these species compete with native taxa for nest cavities within forests is of concern. Our results reinforce the need to manage and protect maturing urban forests to enhance native bird populations. Such actions will also support the recovery of native bird populations at a landscape scale.

Birds collected and reported by the Austrian Novara Expedition while in northern New Zealand in December 1858 and January 1859 are described. These included birds collected at sea east of Northland and Auckland, and birds seen and collected between the Auckland isthmus and Waikato River during 18 days that SMS Novara was at Auckland. Notable records include the earliest known specimen of Pycroft’s petrel (Pterodroma pycrofti), and the earliest record of Kermadec petrel (Pt. neglecta) from near the New Zealand mainland. Scientists from the Novara encountered many species that are now rare or absent near Auckland city and northern Waikato, including brown teal (Anas chlorotis), long-tailed cuckoo (Eudynamys taitensis), New Zealand falcon (Falco novaeseelandiae), kākā (Nestor meridionalis), red-crowned parakeet (Cyanoramphus novaezelandiae), yellow-crowned parakeet (C. auriceps), bellbird (Anthornis melanura), whitehead (Mohoua albicilla), and North Island robin (Petroica longipes), and possibly also North Island saddleback (Philesturnus rufusater) and the extinct North Island piopio (Turnagra tanagra). Other specimens obtained in Auckland (of uncertain provenance) included North Island kokako (Callaeas wilsoni) and hihi (Notiomystis cincta). All these species became much scarcer or extinct following the introduction of ship rats (Rattus rattus) and stoats (Mustela ermina) and other mammalian predators to New Zealand after 1859.