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.
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.
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.
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.
Zealandia (Karori Sanctuary) is a forest sanctuary which is surrounded by a predator-exclusion fence, and is situated in the Wellington city town belt, New Zealand. Following eradication of introduced mammals from within the fence in 1999, 10 species of endemic forest birds were reintroduced between 2000 and 2011, and 2 other species recolonised naturally. Five-minute bird counts were used to assess changes in the Zealandia diurnal forest bird community over 2 time periods: 1995-98 to 2002-05, and 2002-05 to 2013-16, as well as changes over the full 21 year period. Tui (Prosthemadera novaeseelandiae) was the only bird species present before the fence was completed that showed a significant, year-round positive response to mammal removal. Following the recreation of a diverse and abundant endemic bird community post-2005, detection rates for most of the species that were present before 1999 declined significantly. This included highly significant declines in detection rates for 3 native bird species: silvereye (Zosterops lateralis), grey warbler (Gerygone igata) and New Zealand fantail (Rhipidura fuliginosa). These results suggest that populations of the most common and widespread native and introduced birds are only weakly limited by mammalian predation, but can be rapidly outcompeted by restored endemic bird species if predators are removed. The forest bird community in Zealandia is now more similar to that on nearby Kapiti Island (the source site for many of the bird species translocated to Zealandia) than it is to the bird community that existed at the site before the fence was built.
This paper summarises the variations in breeding periodicity in the Australasian – South Pacific region, including recent evidence contrary to previous knowledge. Birds shown to breed in the Samoan islands throughout the year are white-tailed tropicbird (Phäethon lepturus), white-rumped swiftlet (Aerodramus spodiopygius), buff-banded rail (Gallirallus philippensis), brown noddy (Anous stolidus), white tern (Gygis alba) and wattled honeyeater (Foulchaio carunculata). In addition, crimson-crowned fruit-dove (Ptilinopus porphyraceus), blue noddy (Procelsterna caerulea), cardinal honeyeater (Myzomela cardinalis) and Polynesian triller (Lalage maculosa) breed in at least 9 months of the year. The Samoan whistler (Pachycephala flavifrons) has been found breeding in 8 months and the Samoan starling (Aplornis atrifusca) in 7 months of the year.
Over 11 years, the presence of bird species detected within a garden in Kaikōura, New Zealand, were recorded on a weekly basis. Of the 19 species, Eurasian blackbird (Turdus merula merula), house sparrow (Passer domesticus domesticus) and common starling (Sturnus vulgaris vulgaris) were most commonly detected followed by silvereye (Zosterops lateralis), the most commonly detected native bird. New Zealand falcon (Falco novaeseelandiae), Australian magpie (Gymnorhina tibicen) and California quail (Callipepla californica brunnescens) were each seen once. Others recorded were bellbird (Anthornis melanura melanura), chaffinch (Fringilla coelebs), common redpoll (Carduelis flammea), dunnock (Prunella modularis), European goldfinch (Carduelis carduelis britannica), European greenfinch (Carduelis chloris), grey warbler (Gerygone igata), red-billed gull (Larus novaehollandiae scopulinus), song thrush (Turdus philomelos), South Island fantail (Rhipidura fuliginosa fuliginosa), yellowhammer (Emberiza citrinella) and welcome swallow (Hirundo neoxena neoxena). Ten species exhibited significant seasonal variation; 4 showed significant increases and 2 decreases over the 11 years of the study. This study has shown that simple presence/absence observations of a species on a weekly basis can provide an index of numbers, and demonstrate seasonal movements and medium-term changes of bird species within an urban garden.
We compared summer counts of water-birds (November–January, 2012–2016; mainly Anatidae, Phalacrocoracidae, Rallidae, Laridae) at 2 small, shallow, urban lakes set in parkland surroundings: Western Springs Lake (Auckland) and Henley Lake (Masterton), New Zealand. We recorded 25 species of water-birds; 17 at Western Springs Lake and 22 at Henley Lake, with 14 species in common. The average total densities (and biomasses) were 61 birds/ha (113 kg/ha) at Western Springs Lake, significantly higher than the 40 birds/ha (95 kg/ha) at Henley Lake. Ducks (Tadorninae, Anatinae) made the biggest single contribution to numbers at both lakes (40–60% of total water-bird density). Swans and geese (Anserinae) were less common than ducks but because they were heavier birds they accounted for 60–70% of total biomass, and were therefore the main consumers of food and producers of droppings. Introduced water-birds made up 60–70% of the density at both lakes, and 80–90% of the biomass, with no significant differences between lakes. The presence of some native species (in significantly greater total density and biomass at Western Springs Lake), and breeding of the endemic New Zealand scaup at both sites, illustrate the potential conservation value of New Zealand’s small urban lakes.
A national census of breeding black-billed gulls (Larus bulleri) conducted across New Zealand in 1995‒98 estimated 48,000 nests, however the methodology used was unclear. In 2013, the New Zealand threat status for the endemic black-billed gulls was changed to Nationally Critical, based on estimates of recruitment failure causing population decline. To inform future threat classification, the breeding population was re-estimated using aerial surveys to locate, photograph, and count breeding black-billed gulls across New Zealand in 2014‒2016. Large spatial gaps in nest count data during 2014/15 and 2015/16 did not allow for annual variability to be taken into account across the 3 seasons, but the 2016/17 survey successfully covered the entire country. Ground counts of nests were conducted at 16 colonies to determine a correction factor of 0.90 to apply to aerial photograph counts of apparently occupied nests. A total of 60,256 nests were found, with 33,703 nests in Southland and 20,675 nests in Canterbury. The North Island was surveyed on the ground and had 992 nests. Historical survey methods were reviewed, highlighting the inaccuracies of using nest densities or applying factors of gulls/nest to total bird counts based on photographs, as well as only counting individual birds on aerial photographs. Historical data likely overestimated numbers of breeding birds, and the inconsistencies of previous surveys make trend analyses difficult. Key recommendations for future counts include: (i) carrying out ground surveys before flights to determine the breeding stage of birds and hence the optimal time to fly; (ii) taking high resolution and zoomed in photos; (iii) carrying out ground nest counts immediately after flights to determine a correction factor; and (iv) using the same observers for all counts to maintain consistency.
Observations of activities of Hutton’s shearwaters at a natural colony in the Kōwhai River and a new colony at Te Rae o Atiu, Kaikōura Peninsula established by translocations were made during the 2014-15 and 2015-16 seasons. Weights and wing lengths of chicks at the 2 colonies taken at comparable times were similar, as were the dates of first emergence and fledging. Thus, adults flying an additional 20 km each way and climbing over 1200 m had no noticeable effect on chick growth at the mountain colony compared to the sea-level colony. Pre-fledging chicks visited other burrows as did adults at both sites, especially at Te Rae o Atiu, where a greater amount of data showed they visited other burrows throughout the season. While some adults stopped visits before fledging, others were still present after chicks had gone. Seven birds that were translocated from the Kōwhai River colony as chicks to Te Rae o Atiu in 2012 and 2013 were recorded at the Kōwhai colony and 2 of these had previously spent 1 night at Te Rae o Atiu; 28 more from the same cohorts were active at Te Rae o Atiu.
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.