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A census of nesting pairs of the endemic New Zealand king shag (Leucocarbo carunculatus) in 2016 and 2017

Notornis, 65 (2), 59-66

R. Schuckard; M. Bell; P. Frost; G. Taylor; T. Greene (2018)

Article Type: Paper

Following an initial aerial census of breeding New Zealand king shags (Leucocarbo carunculatus) in 2015, 2 further aerial censuses were carried out in 2016 and 1 census in 2017. In 2016, birds were photographed on 2 separate dates using a hand-held camera from inside a fixed wing aircraft. In 2017 the birds were photographed from a fixed-wing plane equipped with an automated camera system mounted below the aircraft. Photographs were independently assessed by 3 observers in 2016 and 2 observers in 2017. Nesting pairs were identified and the figures were averaged per colony for a final estimate of the number of active nests. The first census for 2016 was completed on 6 June and 89 active nests were estimated, compared with 117 nests counted on 1 July. For some colonies, breeding appeared to have just started in June 2016, so an underestimate of active breeders during the first aerial census was the probable cause. The 2017 aerial census was completed on 21 June and we identified 153 active nests. All follow up aerial surveys in 2016 and 2017 were well below the 187 active nests recorded in the 2015 study but within the historic variation. The exception to this trend is Trio Island, where no breeding colony was observed in 2017, the first time this has been recorded at this site.


Buffering artificial nest boxes for Procellariiformes breeding in exposed habitats: investigating effects on temperature and humidity

Notornis, 65 (1), 35-41

J.H. Fischer; J. Chambon; I. Debski; J.A. Hiscock; R. Cole; G.A. Taylor; H.U. Wittmer (2018)

Article Type: Paper

The tendency of various species, including many Procellariiformes, to breed in sub-terrestrial burrows, complicates breeding biology studies. Artificial nest boxes facilitate detailed data collection, but may alter the buffering capacity of natural burrows, especially when these nests are exposed to direct sunlight (e.g., in non-forested habitats). We tested the buffering capacity of artificial nest boxes, equipped with additional insulating features, ex-situ in a non-forested sand dune in New Zealand. Specifically, we compared daily temperature (°C) and relative humidity (%) means, minima, and maxima between artificial nest boxes, Procellariiform burrow replicas, and ambient conditions sourced further inland using linear mixed effects models (LMMs), followed by post-hoc tests. Differences between artificial nest boxes and replicas were non-significant (P > 0.05). Our results thus showed that the applied insulating features were sufficient to retain the buffering capacities expected in natural burrows, even in exposed habitats such as sand dunes. Hence, we encourage the use of insulated artificial nest boxes in breeding biology studies targeting burrowing Procellariiformes (and other sub-terrestrially breeding species) in non-forested areas.



Seasonal and environmental effects on morepork (Ninox n. novaeseelandiae) vocalisations in two forests in Northland, New Zealand

Notornis, 65 (1), 27-34

R. Colbourne; A. Digby (2018)

Article Type: Paper

To investigate factors that might influence calling rates of morepork (ruru, Ninox n. novaeseelandiae), Song Meter SM2+ acoustic recorders were deployed for 12 months recording every night at Hodges Bush (a remnant forest) and Trounson Kauri Park (TKP) in Northland, New Zealand. Three call types were recorded: the classic ‘morepork’ hoot, the ‘wheel’ and ‘wok’. There was no strong seasonal variation in ‘morepork’ hoots from Hodges Bush, although there were fewer hoots from February to March. At TKP, the number of hoots declined from June to August, but the number of ‘wheel’ and ‘wok’ calls remained constant. At dusk, ‘Morepork’ hoots gradually increased until they were at their greatest frequency 3 hours after sunset at both sites. Thereafter, the number of calls reduced through the night at TKP, but remain constant at Hodges Bush until a second peak 2 hours before dawn, after which numbers drop off markedly. The other two call types were constant throughout the night at both localities, but with a pre-dawn peak at Hodges Bush. There was no significant correlation between calls and moon phase at either site. We suggest that it is possible to use vocal activity as a means of monitoring morepork population changes, but more studies are needed to determine variations between sites and different population densities.

Estimates of local occupancy for native land birds from the New Zealand bird atlases

Notornis, 65 (4), 223-236

S. Walker; A. Monks (2018)

Article Type: Paper

We describe the creation of a standardised set of data from the two national atlases of bird distribution compiled by the Ornithological Society of New Zealand. The data provide estimates of local occupancy probability for each of 64 taxa of native land birds, in each of 2,155 grid squares covering the North, South, and Stewart islands, in two measurement periods (September 1969 – December 1979, and December 1999 – November 2004). Because these local occupancy estimates were derived on an identical basis for each bird taxon and each time period, they enable unbiased comparisons between time periods and among species. Links to permanent data repositories of the original and standardised data are provided.

Major changes in the red-billed gull (Larus novaehollandiae scopulinus) population at Kaikoura Peninsula, New Zealand; causes and consequences: a review

Notornis, 65 (1), 14-26

J.A. Mills; J.W. Yarrall; J.M. Bradford-Grieve; M. Morrisey; D.A. Mills (2018)

Article Type: Paper

We use previously published and new data from a long-term study of the red-billed gull (Larus novaehollandiae scopulinus) population at the Kaikoura Peninsula to review causes and consequences of population change. Currently the largest colony in New Zealand, the Kaikoura population, has undergone major changes over the past 52 years. In 1994 the population began to decline, and between 1983 and 2003 it dropped by 51%. Fledging success varied markedly between seasons. The major cause of reproductive failure was predation by introduced mammals, especially ferrets (Mustela furo) and feral cats (Felis catus). These predators became a problem when rabbits (Oryctolagus cuniculus) and hares (Lepus europaeus) increased in number, enhancing the predators’ survival over-winter. Periodic failure in the availability of euphausiids, the main food of red-billed gulls, swamping of nests during high seas, and chilling of nestlings during long periods of bad weather also have been set backs to the population. However, in the absence of predation, these factors produced only a temporary impact to the population of long-lived gulls. The decline in both body size and survivorship of adults over the last 5 decades indicates that there are other factors at work, and indicate that the population has experienced some form of unfavorable environmental condition or stress over a long period.


From wetlands to islands: morphological variation, plumage and song in Pacific island Acrocephalus warblers

Notornis, 65 (4), 202-222

B.D. Bell (2018)

Article Type: Paper

Acrocephalus warblers occur across Eurasia, Africa, and Australasia, where they are typically migratory, wetland species, but also occur on islands as sedentary endemics in drier habitats, including forest and scrub. External morphology and song amongst Pacific island Acrocephalus warblers were investigated and comparisons made with Acrocephalus species elsewhere. There was a range of sizes between Pacific island Acrocephalus warblers, many being larger than migratory continental species. Bill:wing length ratios were higher in most Pacific species, and their wings more rounded, than most continental species, but less rounded than swamp-warblers of Africa and adjacent islands. Plumages of W and N Pacific species resembled reed-warblers elsewhere, but in SE Polynesia were more varied, brown or grey dorsally, shaded olive, yellow or rufous, and pale ventrally, shaded white, yellow or buff-white, with a melanistic morph on Tahiti. Spectrographic analysis showed a gradient of song complexity from continental and Marianas/Micronesia species (A. hiwae, A. syrinx), through to A. taiti and A. vaughani on the Pitcairn islands, which had no song. The mean frequency of Pacific island reed-warbler songs was inversely correlated with mean body size.

The status of the red-billed gull (Larus novaehollandiae scopulinus) in New Zealand, 2014–2016

Notornis, 65 (1), 1-13

P.G.H. Frost; G.A. Taylor (2018)

Article Type: Paper

A national survey of breeding red-billed gulls (Larus novaehollandiae scopulinus) was carried out during 2014–2016 to establish the present status of the species. Observers were asked to find and report all breeding colonies, starting with a check of previously reported breeding sites. Standardised means of conducting these surveys were developed, publicised, and largely applied. Around 27,831 pairs of red-billed gulls were recorded nesting in New Zealand during the survey: 14,713 pairs at 122 South Island sites; 12,676 pairs at 124 North Island sites; and 442 pairs at 14 sites on the Chatham Islands. Other than colonies on the Three Kings Islands (1,763 pairs) and Takapourewa/Stephens Island (1,250 pairs) there were no large concentrations on offshore islands. The largest mainland concentrations were at Kaikoura (3,210 pairs), Taiaroa Head (2,145), Rotorua (2,277) and Marsden Point (1,190). Although the accuracy of previous estimates is questionable, the red-billed gull nevertheless appears to have declined nationally since the mid-1960s. Possible reasons for the decline are discussed and a proposal for future monitoring of the species is proposed.


An estimate of the Hutton’s shearwater (Puffinus huttoni) population in the Kaikōura region using colour-marking in 2002 and 2014

Notornis, 65 (4), 196-201

L.K. Rowe; P.R. Scofield; G.A. Taylor; R.J. Barker (2018)

Article Type: Paper

In September 2002 and 2014 respectively, 2,077 and 1,704 prospecting Hutton’s shearwaters were colourmarked on the ventral plumage at their breeding grounds at Kōwhai River, Seaward Kaikōura Ranges, New Zealand. Large numbers (425,516 in 2002, and 106,900 in 2014) of marked and unmarked birds were then counted from small boats off the Kaikōura coast between Haumuri Bluff and Ohau Point. A hypergeometric sampling model was fitted these counts, leading to population estimates of N =̂ 459,290 (95% CI = 434,306-484,733) birds in 2002 and N ̂ = 590,407 (95% CI = 543,992–642,697) individuals in 2014. These estimates include both breeding and non-breeding birds and indicate that between 2002 and 2014 the population trend was about +2% per year.



A video camera assessment of morepork (Ninox novaeseelandiae) diet and breeding success on Tiritiri Matangi Island

Notornis, 65 (4), 187-195

S.A. Busbridge; J.R. Stewart (2018)

Article Type: Paper

An observational study on the diet and breeding success of morepork (ruru; Ninox novaeseelandiae) was undertaken using video capture methods during the 2016-2017 breeding season on Tiritiri Matangi Island. The study investigated diet composition, frequency of prey deliveries, timing and frequency of chick provisioning, the behaviour of morepork and their young at 10 nest sites, and considered the possibility that morepork predation was having a negative impact on species of conservation importance. Tree wētā (Hemideina spp.) were found to be the most common prey type consumed at nest sites. Evidence of predation of bird species of conservation importance including stitchbird (hihi; Notiomystis cincta) was also found. Prey species continue to exhibit positive population growth rates, indicating predation rates are too low to have a significant destabilizing effect. However, as the population of moreporks has also grown, it is recommended that their impact on prey species be monitored.


Phylogeographic structure and a genetic assignment method for Buller’s albatross ssp. (Thalassarche bulleri ssp.)

Notornis, 65 (3), 152-163

J.R. Wold; C.J.R. Robertson; G.K. Chambers; P.A. Ritchie (2018)

Article Type: Paper

Between 2002 and 2011, Buller’s albatrosses (Thalassarche bulleri bulleri and T. b. platei) accounted for 34% of albatross interactions in New Zealand trawl fisheries. However, the relative impact of commercial fisheries on each taxon is uncertain as identifying individuals by morphology is challenging. The aim of this research was to develop a genetic identification method for the 2 taxa. To this end, DNA was isolated from blood samples collected from a total of 73 birds breeding at northern Buller’s albatross colonies on the islets of Motuhara and Rangitatahi (total n = 26) and southern Buller’s albatross colonies located on Solander Island and North East Island (total n = 47). The degree of genetic differentiation between northern and southern Buller’s was estimated by using DNA sequences from a 221 bp segment of the mitochondrial Control Region. The genetic structure between northern and southern groups was high (pairwise ΦST = 0.621, P < 0.001). A Bayesian assignment method was used to determine provenance of individuals randomly sampled from fisheries bycatch (n = 97). All bycatch individuals were assigned with maximum probability to either the northern (n = 19) or southern taxon (n = 78; P = 1.00). This study demonstrated that sequences from the mitochondrial control region could reliably be used to assign individuals to either northern, or southern breeding populations, and can be used for determining the provenance of seabird bycatch.

North Island brown kiwi (Apteryx mantelli) monitoring at Whenuakite: Trend comparison of observer and acoustic recorder collected call counts

Notornis, 65 (4), 179-186

P. Stewart; M. Hasenbank (2018)

Article Type: Paper

Observer call count surveys are utilised throughout New Zealand to monitor kiwi populations. The development of affordable autonomous acoustic recorders by the Department of Conservation has enabled the collection of large quantities of digital data. Utilising call count data from the North Island brown kiwi (Apteryx mantelli) monitoring programme at Whenuakite from the 2010 and 2015 survey periods, a retrospective comparison between data collected by human observers and acoustic recorders was undertaken. Both survey methods indicated an increase in the number of kiwi calls per hour between the 2010 and 2015 surveys. The overall ratio of the number of calls per hour detected by acoustic recorders to those detected by human observers was 1:1.52. Results from the occupancy modelling indicated that the average detection probability for human observers was almost twice as high as that for acoustic recorders. Furthermore, increasing the number of sites for monitoring kiwi populations improved the associated level of precision of the derived occupancy probability estimates. Adjusting the survey design to the underlying characteristics of the kiwi population are therefore important to gain reliable estimates of their population trajectory.