More than 3,500 Holocene bones, representing at least 853 individual birds, have been recovered on the uninhabited subantarctic Auckland Islands, south of New Zealand. Today this island group has a rich seabird and land-bird fauna, although there have been at least four bird extinctions (a duck, two petrels and a plover) due to predation by introduced mammals and hunting by humans. The Holocene bone fauna, overwhelmingly from sand dunes on Enderby Island, is dominated by seabirds still found at the island group (particularly diving petrels Pelecanoides spp., southern royal albatrosses Diomedea epomophora, and prions Pachyptila spp.). Remains of all endemic taxa (apart from the Auckland Island tomtit Petroica macrocephala marrineri) were recovered from the deposits. All the taxa known to have gone extinct at the island group have now been recovered in Holocene bone deposits, except for the shore plover (Thinornis novaeseelandiae). The deposits indicate also that the abundance of other species has changed. For example, both the eastern rockhopper penguin (Eudyptes filholi) and white-chinned petrel (Procellaria aequinoctialis) are common in the Enderby Island deposits but are rare on the island today, and the Auckland Island rail (Lewinia muelleri) is present as bones in these dunes but has no historical records from the island. This information on the prehistoric distributions of birds will assist the management of the avifauna of the Auckland Islands, which is currently the subject of a major ecological restoration programme.
Since the European discovery of the Auckland Islands, at least ten species of land mammals have been introduced there. Most arrived in the first half of the ninteenth century during periods of exploitation by sealers and whalers, followed by short-lived Māori and European settlements at Port Ross. Several species required multiple introductions before becoming established. For those populations that naturalised, cattle (Bos taurus) occupied Enderby Island and were eradicated by 1993, goats (Capra aegagrus hircus) remained restricted to the northern end of Auckland Island and were eradicated by 1991, while pigs (Sus scrofa) spread across the entire Auckland Island and remain there today. Rabbits (Oryctolagus cuniculus) established on Rose and Enderby Islands, and were eradicated in 1993. Cats (Felis catus) and mice (Mus musculus domesticus) were both first recorded in 1840 on Auckland Island and remain there today. Rats (Rattus spp.) have never established on the Auckland Islands. Collectively, cattle, goats, sheep (Ovis aries), pigs, and rabbits transformed habitats and altered ecosystem processes, and suppressed tussock, megaherbs, and woody vegetation on Auckland, Enderby, Rose, Ewing, and Ocean Islands. Cats and pigs are together responsible for the extirpation or major reduction of surface-nesting and burrowing seabird colonies, and ground-nesting land birds from Auckland Island. Before dying out on Enderby Island, pigs had similar impacts there. Mice have altered invertebrate community composition and are likely responsible for lower abundancies of wētā (Dendroplectron aucklandense) and large weevils (Curculionidae) on Auckland Island. Disappointment Island remained free of introduced mammals, while on Adams Island they had only fleeting and minimal impact. Humans also had direct impacts on birds through hunting for consumption, with large surface-nesting seabirds severely affected around Port Ross. The Auckland Island merganser (Mergus australis) was driven to extinction by presumed mammal predation and well-documented museum collecting. Eradication of pigs, cats, and mice from Auckland Island and Masked Island (Carnley Harbour) would remove the last introduced mammals from the New Zealand subantarctic region.
Auckland Island snipe (Coenocorypha aucklandica aucklandica) are presumed to have occurred throughout the Auckland Island archipelago but became restricted to a subset of the islands following mammal introductions. Snipe were known to have survived on Adams Island, Ewing Island, and Disappointment Island. However, it is uncertain whether snipe were continually present on Enderby Island and/or adjacent Rose Island. These islands lie near Ewing Island, and both hosted a suite of introduced mammals until the last species were eradicated in 1993. Using SNPs generated by ddRAD-Seq we identified four genetically distinct groups of snipe that correspond to the expected three refugia, plus a fourth comprised of Enderby Island and Rose Island. Each genetic group also exhibited private microsatellite alleles. We suggest that snipe survived in situ on Rose and/or Enderby Island in the presence of mammals, and discuss the conservation implications of our findings.
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.