This paper describes the birds of Disappointment Island, a small pristine island in the subantarctic Auckland Islands archipelago, from an accumulation of observations made by ornithologists during 16 visits to the island during 1907–2019. The island supports large populations of both the Auckland Island rail (Lewinia muelleri) and the Auckland Island teal (Anas aucklandica), most of the global population of the New Zealand endemic white-capped mollymawk (Thalassarche cauta steadi) – an annual average of 63,856 breeding pairs during 2009–17, an estimated 155,500 pairs of the circumpolar white-chinned petrel (Procellaria aequinoctialis), and unquantified numbers of smaller petrels. The topography and vegetation communities of the island are described, the history of visits by ornithologists to the island is outlined, and a list of bird species and their breeding status is recorded.
Thinornis rossii is a charadriiform taxon represented by a single specimen reportedly collected on the Auckland Islands, south of New Zealand, in 1840, and obviously closely related to the shore plover (T. novaeseelandiae), of mainland New Zealand and the Chatham Islands. Since the early 20th century, the name T. rossii has commonly been treated as a synonym of T. novaeseelandiae owing to doubts over its provenance based on an untraced quotation from the naturalist (Robert McCormick) who was presumed to have collected it. However, there seems to be no other evidence that the specimen might originate from somewhere close to modern-day Auckland, in the northern part of New Zealand’s North Island, rather than the Auckland Islands, despite the fact that the relevant collecting expedition visited both areas. Moreover, the untraced quotation questioning the Auckland Islands origin seems very possibly to be an artefact of a misremembered reading of McCormick’s unpublished diary or his memoirs, and the circumstantial published and unpublished evidence points with reasonable strength to the bird having been collected where originally stated. Morphological characters (darker, browner upperparts, brownish-grey flanks, longer central toe) suggest that T. rossii might be a valid (but extinct) taxon most appropriately ranked at subspecific level, but the possibility remains that it represents a melanistic specimen. Ideally, the type should be subject to a counterpart molecular investigation.
We analysed standardised estimates of local occupancy probability of 13 species of native wading birds, terns and gulls (order Charadriiformes) derived from the New Zealand Ornithological Society’s national Atlas of Bird Distribution collated in 1969–1979 and 1999–2004. We show systematic patterns in changes with taxonomic level of endemism, breeding habitat (coastal or inland), and location (distance from the coast, road density, and degree of land development for agriculture and forestry). The main changes were decreases in endemic inland breeding species within their inland South Island breeding ranges, and increases in most coastal-breeding species and some inland-breeding species around much of the coast, especially near urban centres in the North Island. Our results are consistent with both intensive land use and predation contributing to widespread declines of inland-breeding species across inland South Island. Potential causes of occupancy changes around the coast are less clear, and we offer some suggestions.
In New Zealand’s subantarctic Auckland Islands, the island-wide population size of white-chinned petrels (Procellaria aequinoctialis) is unknown. On ten islands in the group, surveys for burrow distribution were followed by whole-island burrow counts or stratified random sampling of white-chinned petrel habitat. White-chinned petrel burrow density, burrow occupancy, and slope-corrected surface areas were used to calculate the breeding population size. Burrows were patchily distributed and most abundant in dense megaherb communities. White-chinned petrel burrow density at Adams Island was 701 burrows/ha (95% CI: 480–803 burrows/ha). Burrow occupancy was 0.59 ± 0.02 (mean ± se) at the start of incubation. An estimated 28,300 (10,400–44,800) white-chinned petrel pairs breed on Adams Island. Including the small colonies on Ewing, Monumental, and Enderby Islands (together c. 100 pairs) and the estimated 155,500 breeding pairs on Disappointment Island, the Auckland Island group has an estimated 184,000 (95% CI: 136,000–237,000) pairs of breeding white-chinned petrels.
Enderby Island is a much-visited small island in the New Zealand subantarctic, and is an important area for birdlife. However, despite this, the bird community of Enderby Island has never been systematically described. We summarise bird records on Enderby Island from 1840 to 2018. Using these data we describe the bird community with an emphasis on resident species, and compare the frequency of sightings before and after eradication of invasive mammals in 1993. We also investigate trends in bird sightings from 1992 to 2018. There was a significant increase in the sightings of some species, including tui (Prosthemadera novaeseelandiae) and silvereye (Zosterops lateralis), and a significant decrease in others, including white-fronted tern (Sterna striata). Some species, such as New Zealand falcon (Falco novaeseelandiae) and Auckland Island snipe (Coenocorypha aucklandica aucklandica), have recovered successfully following dramatic historical declines. We hypothesise that these trends in sightings are driven by changes in human exploitation, the introduction and subsequent eradication of browsing mammals and mice, changes in the abundance and structure of the invertebrate community, and changes in vegetation cover. However, we believe that trends in sighting rates of southern royal albatross (Diomedea epomophora) may be an artefact of changes in visitor behaviour following the construction of a boardwalk, rather than changes in the species’ abundance.
We undertook a survey of coastal wetlands in Canterbury (NZ) during a widespread river flooding event in Spring 2013 to quantify numbers and distribution of wrybill (Anarhynchus frontalis). We found 740 birds, of which 685 (92.6%) were at Lake Ellesmere/Te Waihora. We calculate that 15.8% of the estimated effective wrybill breeding population were displaced from breeding rivers by floods at this time. Our findings support the evaluation by Dowding & Moore (2006) that the network of wetlands along the Canterbury coast appears to be of critical importance to wrybill as breeding season flood refugia.
Ten white-headed petrels (Pterodroma lessonii) from Adams Island, Auckland Islands, were tracked during 2011–14 using miniature geolocators, in the first study to examine the at-sea movements and key foraging areas of this pelagic seabird. Data revealed extensive migrations west to South Africa and east into the central South Pacific Ocean. The birds returned to colonies Aug–Oct. Median departure on pre-laying exodus was 24 Sep. Birds were away for up to 77 days during pre-laying and moved west towards the Indian Ocean. Laying occurred 24 Nov–10 Dec. The first major incubation shifts by males and females were c. 19 days in duration. The maximum foraging range during incubation was 5,230 km from the colony, the most distant recorded by any seabird during this breeding stage. After eggs hatched in January, some birds foraged off Antarctica in sea temperatures down to –1°C. Birds spent the inter-breeding period in disjunct areas (off South Africa, south of Australia, Tasman Sea, and South Pacific Ocean). This study revealed an unusual courtship behaviour not recorded previously in other seabird species. Females returned from distant oceans to spend just a few days ashore in the pre-laying period before leaving the breeding site until the following spring. The males also skipped breeding at the same time as their mates, but returned earlier in the season. The new knowledge gained about the breeding activity of this species will assist with future population assessments.
Adams Island (9,693 ha) is the second-largest island in the Auckland Islands group, and the largest island in New Zealand on which introduced mammals have never become established. Adams Island is forested on the northern sheltered parts of its coastline, and has shrubland, grassland, and fellfield at higher altitudes, and herb-field in fertile open sites. Sheer cliffs dominate the exposed, southern side of the island, and above them, narrow shelves support lush herb-fields. This diversity of habitat in close proximity supports unique communities of birds, with most species in remarkable abundance due to the absence of introduced predators. With the notable exception of the Auckland Island merganser (Mergus australis), the island’s birdlife is close to what it would have been in pre-human times, and includes high densities of species that are now rare or missing on nearby Auckland Island. This paper describes the island, the history of ornithological exploration, and the past and current state of the avifauna. The 48 extant bird species recorded from the island comprise 22 land birds and 26 seabirds, of which 34 species (16 land birds and 18 seabirds) have been recorded breeding or are likely to be breeding there. Eight species introduced to New Zealand have also made their way to Adams Island, and six probably breed there.
The wrybill (Anarhynchus frontalis) is an endemic plover that breeds only in braided rivers east of the main divide in the South Island of New Zealand. It is threatened by a range of factors, including loss and degradation of habitat, flooding, and predation. We monitored wrybills in 2 sites in the Tekapo River and 2 in the Tasman River in the Mackenzie Basin, South Canterbury, during 3 breeding seasons (1997/98–1999/2000). We aimed to compare survival and productivity between areas with and without trapping (mammalian predator control) to determine whether predator control was associated with higher survival and/or breeding success of wrybills. In the Tekapo River, results were similar between trapped and un-trapped areas, suggesting that control had little effect. In the Tasman River, there were large differences between the two sites and trapping appeared to be beneficial; in the upper river (un-trapped), productivity and survival were very low and in the lower (trapped) site they were high. Over the whole study, 67.3% of nests hatched, and depredation was the largest cause of nest failure. Fledging success (the proportion of chicks hatched that fledged) averaged 35.4%. Losses at the chick stage were higher than at the egg stage, and there was only a weak correlation between nesting success and overall breeding success; we therefore caution against the use of nesting success as a proxy for overall breeding success. Productivity averaged 0.49 chicks fledged per pair over the whole study; when the very low values from the upper Tasman site were excluded, productivity averaged 0.61. Survival of adult male wrybills was lower than survival of females in all four study sites. Measurement of adult survival is important in determining the full effect of predator control (and in determining population trends) but is often overlooked. At the time of our study, wrybill populations in 3 of our 4 study sites appeared not to be self-sustaining and, in the absence of immigration, were in decline. A number of factors, including depredation by mammals, can affect breeding success. Trapping may be beneficial, but temporal and geographic differences in predator densities, as well as variability in other threats (such as flooding and levels of avian predation) mean that predicting when and where mammalian predator control may benefit wrybills is currently difficult.
Nineteen cases of physical deformities, colour aberrations, and unusual eggs were recorded in emperor penguins (Aptenodytes forsteri) and Adélie penguins (Pygoscelis adeliae) from the Haswell archipelago in the Davis Sea, East Antarctica, during 1956–2016. Two very small eggs and one very large egg were recorded from emperor penguins, and two very small eggs from Adélie penguins. Physical deformities included beak deformities in two emperor penguin adults and two chicks, and two chicks had deformed spines. Colour aberrations included the ino mutation in a juvenile emperor penguin, and examples of dilution (two cases), progressive greying (two cases), and isabellinism in adult Adélie penguins. Feather-loss disorders were recorded in two downy emperor penguin chicks. Data on the occurrence of identified abnormalities and disorders are given. These cases provide a baseline for assessing changes in the frequency of physical abnormalities in these Antarctic penguin species.
Ruddy turnstone (Arenaria interpres) is the third most numerous Arctic-breeding wader that occurs in New Zealand. Numbers of turnstones in New Zealand have declined but identification of potential causal factors is hampered by lack of information of the migration routes used. Re-sights of marked birds indicate that some New Zealand turnstones pass through East Asia and Australia on both northward and southward migration. Information on possible migration through the Pacific is lacking.
This first breeding population estimate of northern giant petrels (Macronectes halli) in the Auckland Islands group involved whole-island censuses, apart from the main Auckland Island, in the 2015-16 breeding season, and multi-year repeat visits to a subset of island colonies. Parallel line-transects in giant petrel habitat were used to survey the number and spatial distribution of pre-fledging chicks. The Auckland Islands 2015-16 whole-island census resulted in a count of 216 northern giant petrel chicks on eight of the 15 islands in the group. Applying a simple correction factor, the breeding population in 2015 is estimated as c. 340 breeding pairs (range 310–390). This estimate is higher than historical non-quantitative records of 50–200 breeding pairs. Multi-year counts on Enderby, Rose, Frenchs, Ocean, Disappointment, and Adams Islands showed some inter-annual variability, but other island colonies remained more stable. The northern giant petrel colony on Enderby Island has increased from two chicks in 1988 to 96–123 chicks in 2015–18 (four annual counts undertaken).
The Auckland Islands are the largest island group in the New Zealand subantarctic region, and have the most diverse avifauna, including eight endemic taxa. We present the first comprehensive review of the avifauna of the Auckland Islands, based on a database of 23,028 unique bird records made between 1807 and 2019. At least 45 species breed (or bred) on the islands, with a further 77 species recorded as visiting the group as migrants, vagrants, or failed colonisers. Information on the occurrence of each species on the different islands in the group is presented, along with population estimates, a summary of breeding chronology and other reproductive parameters, and diet where known. The frequency at which 33 bird species were encountered during visits to the seven largest islands is compared graphically to facilitate comparison of each island’s bird fauna in relation to habitat differences and the history of introduced mammals. Disappointment Island (284 ha) is the least modified island in the group. However, it lacks forest, and so has a very restricted land bird fauna, lacking ten species that breed on other islands in the group. Auckland Island (45,889 ha) is the only major island in the group where introduced mammals are still present. As a result, it also has a depauperate bird fauna, with at least 11 species completely absent and a further seven species reported at lower frequencies than on the next largest islands (Adams and Enderby Islands).
Banded dotterels (tūturiwhatu, Charadrius bicinctus bicinctus) are small plovers inhabiting New Zealand’s braided rivers, estuaries, seashores, and open country. They are considered Nationally Vulnerable under national threat listing criteria, but with uncertainty around the trend estimation. We collated and reviewed counts of banded dotterels on their braided river breeding grounds from throughout the country, 1962–2017, to describe their distribution, assess population trends, estimate rates of population change, and assess the appropriateness of the threat status given to this species. We also used nationwide winter count data for banded dotterels from 1984 to 2018 as an independent measure to compare trends. Banded dotterel counts were recorded for 119 braided and shingle river reaches, mostly in the South Island (87%) with far fewer rivers in the North Island (13%). The sum of banded dotterel counts was 12,730 birds when tallying the most recent counts/river. Although they were most widespread in the South Island, particularly Canterbury, the majority (>50%) of dotterels counted on the most recent surveys were from just 10 (8%) rivers with the largest single concentrations on three Hawkes Bay rivers. Counts suitable for long-term trend analysis were only available for South Island sites. Widespread declines in banded dotterel count indices were recorded. The weighted mean annual rate of change across 33 South Island rivers was -3.7% p.a. (per annum), which equates to a 52.3% decline over 20 years (~3 generations). We also detected a negative trend in dotterel numbers based on national winter count data, but of a smaller magnitude (-1.4% p.a., equating to a 25% decline over 20 years). However, trends in Australia, where c. 60% of banded dotterels over-winter, are unknown. In contrast, a significant population increase was measured on the Hakatere Reach of the South Ashburton River, which has intensive, sustained predator control, and several predator trapping initiatives on other braided rivers and coastal areas indicate declines can be reversed with management if applied at an extensive landscape scale. Banded dotterels are subject to a wide range of threats including very high levels of predation by invasive predators, human disturbance on breeding grounds, and habitat loss and degradation. Using the precautionary principle, the rates of decline on South Island braided rivers confirm the classification of Nationally Vulnerable using the NZ Threat Classification system. However, results suggest that the IUCN threat status for banded dotterel should be reclassified from Least Concern to Endangered.