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Post-translocation movements and ranging behaviour of roroa (great spotted kiwi, Apteryx maxima)

Notornis, 69 (3), 135-146

P. Jahn; J.G. Ross; V. Mander; L.E. Molles (2022)

Article Type: Paper

Translocations are increasingly used in kiwi (Apteryx spp.) conservation management, and their outcome is largely influenced by post-release dispersal and survival. A translocation of roroa (great spotted kiwi, A. maxima) to the Nina Valley, near Lake Summer Forest Park, is the first reintroduction of the Arthur’s Pass roroa population. In 2015, eight wild-caught adults were translocated from Arthur’s Pass National Park, following the release of ten captive-hatched subadults during 2011–13. We monitored the translocated kiwi by radio telemetry during 2015–17. Dispersal was highly variable among the released wild birds. The straight-line distance from the release site to the last recorded location ranged 0.5–10.3 km. Seven of the wild birds remained in the Nina Valley and covered an area up to 1,700 ha (95% utilisation distribution). Releasing the wild birds had no measurable impact on the ranging behaviour of previously released subadults. The current population founder group comprises a maximum of 13 unrelated individuals, and therefore further releases are necessary for a genetically viable population. Additionally, expansion of the pest-controlled area is crucial for the long-term persistence of the reintroduced population in the Nina Valley.

Habitat loss drives population decline and reduced mass of Rakiura tokoeka (Apteryx australis australis, Stewart Island brown kiwi,) at Mason Bay, Stewart Island/Rakiura

Notornis, 69 (3), 147-157

H.A. Robertson; R.M. Colbourne (2022)

Article Type: Paper

Between 1993 and 2018, the number of Rakiura tokoeka (Apteryx australis australis, Stewart Island brown kiwi) territories in 125 ha of retired farmland near Island Hill Homestead, Mason Bay, declined from 17 to 12 at a mean rate of 1.43% per year, and the minimum number of adults declined by 1.39% per year. These rates triggered a New Zealand conservation status of ‘Nationally Endangered’ for the subspecies assuming that they were typical of the whole of Stewart Island/Rakiura. Feeding habitat for tokoeka has been lost as the study site reverts from rough pasture to flax (Phormium tenax) and scrub; the mean mass of adult birds has decreased by 7.5% over 30 years despite a 30% decline in population density. Key predators of adult kiwi are absent, and predation of Rakiura tokoeka by feral cats (Felis catus) is known but is likely to be insignificant. With a conservative population estimate of 15,000–20,000 adults, and with the decline likely localised at Mason Bay, the conservation status of Rakiura tokoeka is more appropriately classified as ‘At Risk – Naturally Uncommon’. This research highlights the risks of extrapolating results from a single study, in this case with a limited geographical extent rather than a limited duration.

Continued increase in red-billed gulls (Larus novaehollandiae scopulinus) at Otago, southern New Zealand: implications for their conservation status and the importance of citizen science

Notornis, 69 (2), 81-88

C. Lalas; S. Carson; L. Perriman (2022)

Article Type: Paper

A published national survey of red-billed gulls (Larus novaehollandiae scopulinus) in 2015 recorded about 28,000 nests in New Zealand, a 30% decrease in 50 years. We compared nest numbers in 2020 at Otago, south-eastern South Island, with published records for 1992–2011 and 2015. In contrast to trends further north, numbers at Otago have increased but the average annual rate of increase dropped from 6–10% for 1992–2011 to 2% for 2011–2020. Citizen science provided a valuable input in 2020 with records of breeding at previously undocumented urban locations. The about 6,000 nests at Otago in 2020 probably account for 20% of the national total.

A basic statistical approach to determining adult sex ratios of moa (Aves: Dinornithiformes) from sample series, with potential regional and depositional biases

Notornis, 69 (3), 158-173

R.N. Holdaway; M.E. Allentoft (2022)

Article Type: Paper

Adult sex ratio is a basic component of breeding systems. Estimates of sex ratios of moa (Aves: Dinornithiformes) have ranged from near balanced to significantly female-biased. However, ratios have usually been estimated by simple ratios of females to males identified by some level of sexual size dimorphism or, at most, tested against a balanced ratio by χ2 test. Application of binomial tests confirmed a great heterogeneity, and high levels of uncertainty in estimates of moa sex ratios from different areas and from different kinds of fossil deposits. Large samples gave more constrained estimates than small, but even for some of the larger, binomial analysis often revealed a range of possible ratios, including one with a bias to males. Some causes of extreme values for swamp and lake bed deposits, including sexual differences in territorial behaviour, have been suggested before. However, a new issue – significant and sometimes abrupt changes in female and perhaps male body size through time – was identified here from series of genetically identified and radiocarbon dated moa from North Canterbury, New Zealand. The size changes compromise allocation of individuals to sex by morphometrics of limb bones, especially in undated samples. Intensive radiocarbon dating of series of genetically sexed moa of different taxa from a range of areas will be required to identify potential regional and temporal differences in their sex ratios before any interpretation of the evolution of size dimorphism and breeding systems based on moa sex ratios will be possible.

Widespread ground-nesting in a large population of feral rock pigeons (Columba livia) in a predator-free and urban native forest

Notornis, 68 (3), 224-233

J.V. Briskie; L. Shorey (2021)

Article Type: Paper

We found widespread nesting on the ground in a large population of feral rock pigeons (Columba livia) in an urban, but predator-free native forest reserve in Christchurch, New Zealand. Ninety-seven percent (n = 77) of rock pigeon nests were located on the ground, with most placed either at the bases of large kahikatea (Dacrycarpus dacrydioides) trees or under a tangle of vines on the forest floor. Clutch size was 2 eggs in all nests, with a hatching success of 93.9% in nests that survived to the hatch stage. Overall nest success was higher (60.0%) than in other populations of rock pigeons, with half of nest failures attributed to culling of the population that occurred during the course of our study. On average, rock pigeons fledged 1.60 chicks per successful nest. No ground nests were located outside the boundary of the predator- proof fence, suggesting pigeons were able to assess predation risk when selecting nest site location. Ground nesting by rock pigeons may be a way to avoid damage to nests in the canopy by strong winds or predation from aerial predators such as harrier (Circus approximans), which also occur in the reserve. Based on density of nests, we estimated a breeding population of 226 to 258 rock pigeons in the 7.8 ha reserve. The high number of pigeons in the reserve highlights the need for further studies on how populations of introduced species of birds in New Zealand respond to control of mammalian predators and the effect this may have on sympatric native species.

Dominance interactions among New Zealand albatrosses and petrels at ecotourist boats

Notornis, 68 (1), 51-64

P.R. Martin; J.V. Briskie (2021)

Article Type: Paper

Aggressive interactions among species competing for resources are common and usually asymmetric, leading to consistent dominance hierarchies. Here, we document aggressive interactions among six albatross and three petrel species off southern New Zealand, in response to supplemental food provided by ecotourism boats. For species with sufficient sampling, we found a consistent dominance hierarchy, with Diomedea antipodensis gibsoni > D. epomophora > Macronectes halli > Thalassarche cauta > T. salvini > T. bulleri > Daption capense. The heavier species was dominant in most species pairs. Dominant species monopolised the food provided by displacing subordinates. However, subordinate species appeared to gain access to some food through fast responses, greater manoeuvrability, and feeding on small pieces of food ignored by dominants. Similar congregations and interactions at natural food sources suggest that dominance hierarchies may play an important role in structuring the diverse seabird communities in the southern oceans.

Garden birds at Rangiora, Christchurch, and Kaikōura, South Island, New Zealand: results from banding 1961–2016

Notornis, 68 (3), 208-223

L.K. Rowe (2021)

Article Type: Paper

Birds were banded in gardens at Rangiora 1961–1977, Christchurch 1977–2000, and Kaikōura 2000–2016. In total, 21,565 birds of 14 species were captured in mist-nets or traps and banded; 3,213 individuals were recovered or recaptured. The most common species banded was silvereye (Zosterops lateralis lateralis) with 15,349, followed by house sparrow (Passer domesticus domesticus) with 4,497, and common starling (Sturnus vulgaris vulgaris) with 430; all other species were less than 300 birds banded which is less than five birds per year. Distance recoveries of note are: silvereyes – Kaikōura to Wellington (153.0 km), Rangiora to Greymouth (146.0 km), Rangiora to Otira (99.0 km), with two more birds over 25.0 km; house sparrow – Christchurch to Homebush (43.5 km), with two more over 25.0 km; common starling – Rangiora to Christchurch (27.8 km); dunnock (Prunella modularis) – local movement (5.1 km). The most significant recoveries from time of banding to recovery are: silvereye – 8.8 years; house sparrow – 8.7 years; starling – 8.0 years; dunnock – 5.3 years. Wing length and mass measurements of Kaikōura birds were generally within published ranges.

Erect-crested penguins on the Bounty Islands: population size and trends determined from ground counts and drone surveys

Notornis, 68 (1), 37-50

T. Mattern; K. Rexer-Huber; G. Parker; J. Amey; C.P. Green; A.J.D. Tennyson; P.M. Sagar; D.R. Thompson (2021)

Article Type: Paper

In October 2019, an expedition to the subantarctic Bounty Islands provided the opportunity to conduct comprehensive ground counts of erect-crested penguins to assess population size and compare numbers to previous surveys. The entirety of Proclamation Island, an erect-crested penguins’ stronghold, was surveyed and number of active penguin nests was determined via ground counts. Drone surveys aiming at assessing seal numbers, provided high- resolution aerial photography allowing spatial analysis of penguin nest densities on four islands, i.e. Proclamation, Tunnel, Spider, and Ranfurly Islands. A total of 2,867 penguin nests were counted on Proclamation Island between 24 and 29 October. Adjusting for the earlier timing of the survey compared to counts conducted since 1997, nest numbers were only marginally lower (~2.4%) than in 1997 and 2004 suggesting that the penguin population has remained stable for the past 20 years; a ~10% reduction in penguin numbers in 2011 seems to be related to warmer than average ocean temperatures that year. Density analysis from drone imagery showed highly heterogenous distribution of penguin nests, with birds preferring areas sheltered from prevailing south-westerly winds. This also means that a previous estimate from 1978 which relied on uniform extrapolation of nest densities to what was assumed to suitable breeding areas substantially overestimated the true population size, thereby contributing to the species current ‘endangered’ threat ranking.
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