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.
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.
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.
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.
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.
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.
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.