Publications Archive

This paper describes North Island kokako (Callaeas wilsoni) recovery actions and outcomes since 2000 at 11 sites with relict populations, and at 12 other mainland and three offshore island sites to where they have been translocated. Populations are now secure on pest-free Te Hauturu-o-Toi / Little Barrier Island and Kapiti Island, and Tiritiri Matangi Island is a valuable advocacy site. Maungatautari is a large (3,300 ha) pest-fenced and pest-free site that has demonstrated rapid kōkako recovery. All other sites are unfenced and require ongoing control of key pests. The national total of kōkako pairs has increased from c. 458 in 2000 to c. 2,327 in 2023; however, latest counts indicate populations at seven sites have declined. Future kōkako recovery will be assisted most by improved, large-scale pest control tools for unfenced mainland sites, and by sustained effective pest control in large key relict populations (Pureora, Te Urewera, Rotoehu, Mapara, and Mokaihaha).

Te Araroa Trail runs for more than 3,200 km between Cape Reinga and Bluff, along the length of Aotearoa New Zealand’s two main islands. All birds seen and heard along the trail during the austral summer were counted in 1,720 contiguous transects during 124 days of walking from north to south between 2 November 2023 and 11 March 2024 (84.7% of transects were 2 km long). A total of 106,207 birds of 107 species were counted during daylight transects, at a mean encounter rate of 32.6 individuals per km. The highest counts were for house sparrow (Passer domesticus – 12,517 birds), chaffinch (Fringilla coelebs – 5,806), and red-billed gull (Chroicocephalus novaehollandiae – 5,427). The species recorded most frequently were chaffinch (62.3% of transects), silvereye (Zosterops lateralis – 58.5%), and Eurasian blackbird (Turdus merula – 56.7%). Bird communities are summarised and compared for 19 sections covering the entirety of the trail, providing a baseline for comparisons within regions and over time. Northern and/or southern limits are presented for 30 species with restricted distributions. Comparison of counts along sections of the trail that were trapped (233 km, including 22.4% of forest) with counts from untrapped forest sections revealed that tūī (Prosthemadera novaeseelandiae), kererū (Hemiphaga novaeseelandiae), and New Zealand fantails (Rhipidura fuliginosa) were more abundant where predator control was undertaken. Twenty of the fantails seen in the South Island were black morph (5.6%), with the remaining 339 (94.4%) pied morph, indicating that the proportion of black morph birds has been stable over the past two decades. In addition to describing bird communities likely to be encountered on different sections of Te Araroa Trail, this account (and the dataset it is based on) provides a baseline for comparing New Zealand bird communities over time and space.

A colony of the Nationally Vulnerable Hutton’s shearwater (Puffinus huttoni) was established by translocations to Te Rae o Atiu, Kaikōura Peninsula from 2005. Weekly observer visits to the wooden nestboxes, and records from passive integrated transponder readers, provided detailed records of breeding activity. Birds visited many nestboxes in a season, with up to 29 birds recorded at one nestbox, and one bird recorded at 23 nestboxes. Breeding started at 4 years for males and 5 years for females. The pre-laying exodus by females averaged 11.8 days; however, there were instances of birds making up to three brief visits back to the colony. Egg laying was usually on the night of arrival back from the pre-laying exodus, and was asynchronous — average 6 November, but as late as 25 December. There were seven instances of two eggs being found in a nestbox in one season, with evidence of relaying in at least one case. The average hatching date was 13 December, incubation averaged 52 days, with a mean hatching success of 58%. Fledgling period was 87 days on average, with a mean success of 88%, resulting in mean productivity of 52%. Chicks left nestboxes on average 8 nights before fledging, before their first migration to Australian waters. Adults stopped visiting the nestboxes on average 17 days before their chicks fledged for females and 8 days for males. Fledging mass averaged 415 g, 75% of the mean peak mass of 550 g. Single parents successfully fledged a chick when the mate was lost or ceased visiting for up to 71 days before fledging, and a light mass chick (310 g) returned to Te Rae o Atiu and paired up. Divorce occurred in 36% of pairings that did not end with the loss of a partner; 87% of birds had at least one divorce, and one bird lost one mate and divorced six times in 13 years. Nestbox fidelity showed changes by many pairs, especially if there has been a change of partner.

Buller’s albatross Thalassarche bulleri is generally considered to comprise two subspecies: T. b. bulleri, which breeds on islands south of the South Island, New Zealand; and T. b. platei, which nests on the Three Kings Islands, off the northern tip of of the North Island, and on outlying islets of the Chatham Islands east of New Zealand. Although the name platei has been widely applied to the latter population, some authors have suggested that its type specimen is in fact a juvenile T. b. bulleri. As a result, those birds breeding in the Chatham and Three Kings groups have sometimes been considered to represent an unnamed subspecies, or even species, given recent evidence of their genetic differentiation. Because our own morphological examination of the specimen was inconclusive as to which population the type of platei belongs, we subjected the individual to molecular testing. From this, we can confirm that the name platei has been correctly applied to the northern population of Buller’s albatross.

The distributions of birds on the islands of Aitutaki were surveyed 3–13 Oct 2024. We describe 22 resident and migratory species across the 17 islands of the almost-atoll Aitutaki, with regionally important colonies of red-tailed tropicbirds (Phaethon rubricauda), red-footed boobies (Sula sula), and wedge-tailed shearwaters (Ardenna pacifica), as well as a population of the IUCN-vulnerable blue lorikeet (Vini peruviana)on Aitutaki’s main island. While Pacific rats (Rattus exulans) and cats (Felis catus) are present on some islands, others potentially remain rat-free. Over the last 25 years, the reef island of Motukitiu has undergone a substantial habitat transformation from introduced coconut forest to native atoll broadleaf forest, enabling the recovery of seabirds.  Prevalent threats to the birds of Aitutaki include the introduction of additional rat species, spread of Pacific rat to currently rat-free islands within the almost-atoll, unsupervised tourism, and habitat modification on the small islands.

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.