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The conservation status of Hutton’s shearwater (Puffinus huttoni) at Shearwater Stream, Kaikōura, New Zealand: a small population at risk?

Notornis, 70 (1), 1-13

Cargill, C.P., Townsend, D., McArthur, N.R., Morgenstern, R., Morrissey, M., Sherley, G., Bell, M. (2023)

Article Type: Paper

Abstract: Hutton’s shearwater (Puffinus huttoni) is a burrowing petrel endemic to the alpine zone of the Seaward Kaikōura Ranges, New Zealand. In November 2019, we accessed an understudied breeding colony at Shearwater Stream in the Puhi Peaks Nature Reserve for the first time since a Mw 7.8 earthquake struck the region in 2016. We measured population parameters and carried out a geomorphological assessment. We estimate that the Shearwater Stream colony supports approximately 3,000 breeding pairs. Ground deformation attributed to the 2016 earthquake did not explain the discrepancy between this estimate and the commonly cited (pre-quake) population estimate of ~8,000 pairs. We highlight the limitations of extrapolated population parameters and of using vegetation cover as a coarse proxy for colony area. We discuss how low burrow occupancy and long-term reductions in the availability of suitable habitat indicate a population at risk of decline. We highlight how stable long-term data for burrow density and breeding success may not be reliable indicators of population health at Shearwater Stream.

Hutton’s shearwater (Puffinus huttoni) at Te Rae o Atiu, Kaikōura Peninsula South Island east coast, New Zealand: a colony established by translocations – 16 years progress

Notornis, 70 (1), 14-30

Rowe, L.K., Howard, T. (2023)

Article Type: Paper

Abstract: A new colony of the endangered Hutton’s shearwaters (Puffinus huttoni) has been established at Te Rae o Atiu on the Kaikōura Peninsula, South Island east coast, New Zealand to provide insurance against catastrophic events at the high-altitude natural colonies in the Kōwhai River and Shearwater Stream, Seaward Kaikōura Range. The translocation of 495 chicks from the Kōwhai River colony was carried out in six operations from 2005 to 2013. Of the 473 fledglings, 97 have been recorded back at Te Rae o Atiu. Chick selection criteria, fledgling mass, fledgling wing length, days present before fledging, and days of emergence before fledging had no bearing on whether chicks returned from their post-fledging migration to Australian waters or not. One hundred and twelve Te Rae o Atiu bred chicks have fledged up until 2020–21. The Te Rae o Atiu fledglings had similar mass and wing lengths, and days emerged prior to fledging, to the translocated fledglings. There were no differences between the groups of Te Rae o Atiu bred birds that returned or did not. At 2020–21, 21 of the 112 second-generation chicks have returned from their initial migration, and the earliest have bred successfully. The colony has grown to about 75 birds producing about 30 eggs, 24 chicks, and 22 fledglings annually. Future growth of Te Rae o Atiu will be reliant on these home-bred chicks as the oldest translocation birds will soon be approaching the end of their breeding lives. Acoustic attraction of birds flying over Te Rae o Atiu from the sea towards the Kōwhai River natal colony has been mostly unsuccessful with only two birds attracted.

A PCR-based assay for screening substrates for Aspergillus fumigatus for application in kiwi hatcheries

Notornis, 70 (1), 31-38

Rowe, S.P., Stott, M.B., Brett, B., Dhami, M.K. (2023)

Article Type: Paper

Abstract: Captive facilities across New Zealand strive to mimic natural conditions for captive animals as closely as possible. In the case of the kiwi (Apteryx spp.), captive habitats are augmented with natural stimuli such as soils, leaf litter, bark, plants, logs, and mosses. Interaction with these introduced stimuli has been shown to encourage normal foraging behaviour and is speculated to aid in inoculating young animals with healthy microbial communities. However, introducing non-sterile natural stimuli into the captive environment also carries the risk of exposing kiwi to diseases such as aspergillosis, coccidiosis, and candidiasis. Aspergillosis is of particular concern to rearing facilities – the disease is most commonly attributed to exposure to Aspergillus fumigatus, an opportunistic fungal pathogen. Here we present a PCR-based screen to qualitatively detect the presence and/or absence of A. fumigatus in soils. Soil samples collected from nesting sites of rowi (Ōkārito brown kiwi, Apteryx rowi) in the Ōkārito region of the West Coast were screened for A. fumigatus using a species-specific primer set coupled with a basic DNA extraction. Willowbank Wildlife Reserve soil and substrate samples were also screened as a baseline comparison representing captive rearing facilities. Results from the assays showed that the extraction technique was effective at isolating A. fumigatus DNA at detectable levels from a variety of soils, and that Ōkārito soils did not harbour a higher abundance of A. fumigatus than those found at Willowbank. This preliminary screening method could be used by facilities in New Zealand to quickly and cheaply screen soils and substrates for A. fumigatus before introducing them to captive enclosures.

Changes in the Mana Island, New Zealand, bird community following mouse (Mus musculus) eradication

Notornis, 69 (4), 243-255

Miskelly, C.M., Beauchamp, A.J., Oates, K.E. (2022)

Article Type: Paper

Abstract: House mice (Mus musculus) have proven to be the most difficult introduced mammal to eradicate from (and keep out of) New Zealand reserves and sanctuaries. Partly as a consequence of this, little is known about how bird communities respond to mouse eradication. Mice were successfully eradicated from 217 ha Mana Island Scientific Reserve, near Wellington, in 1989–90. Five-minute bird count surveys undertaken in spring and autumn before and after mouse eradication revealed that 13 of 22 species were recorded significantly more often after mouse eradication, and just two species were recorded significantly less often following the eradication (and each of these in one only of the two seasons that were compared). Four species had no significant change, and three species showed mixed responses between the two seasons. While the overall pattern was of increased relative bird abundance after mouse eradication, there is limited information on why individual bird species increased during the study period, and whether this was a consequence of mouse eradication. Bird count data revealed that insectivorous passerines may have benefited the most from mouse eradication on Mana Island, suggesting that competition for invertebrate prey was the main impact that mice had on the birds of the island. The use of anticoagulant rodenticides to eradicate mice from Mana Island had little detectable impact on populations of the island’s birds.

Sexing of the endangered Floreana mockingbird (Mimus trifasciatus) using morphometric measurements

Notornis, 69 (4), 256-263

Reyes, E.M.R., Smith, A.N.H., Rueda, D., Sevilla, C., Brunton, D.H., Ortiz-Catedral, L. (2022)

Article Type: Paper

Abstract: Male and female adult Floreana mockingbird (Mimus trifasciatus) have monomorphic plumage features that make them impossible to sex in the field. In this study, we use discriminant function analysis (DFA), a widely used technique, to assess the best measures to determine sex. We measured six morphological characteristics (mass, beak depth, beak width, tarsus length, wing length, and head-beak length) for birds of known sex (determined by molecular techniques) from the two extant populations of M. trifasciatus on Champion and Gardner islets, within the Galápagos archipelago. Using a coefficient of sexual dimorphism, we found that males are significantly larger than females in three of the variables. Discriminant functions using wing length and a combination of wing length + mass, and wing length + tarsus length could classify birds with a 98% level of accuracy. Furthermore, we were able to estimate a robust cut-off point to determine the sex of individuals in the field through a decision tree, using only wing length as morphological variable. Fast and accurate sexing of the bird based on one variable will reduce handling times and minimise stress for captured birds.