We investigated whether the abundance of the South Island robin (Petroica australis australis) could be explained by the abundance, species richness, diversity, or evenness of leaf-litter invertebrates. We recorded robin abundance indices and collected leaf-litter invertebrates in 3 forest types: mature Douglas fir (Pseudotsuga menziesii); mature Monterey pine (Pinus radiata); and old growth kanuka-manuka (Kunzea ericoides – Leptospermum scoparium). Robins were attracted to stations using 5-min playbacks of robin full song in each forest type. Invertebrates were extracted from leaf-litter samples using ‘Tullgren-type’ heat extraction funnels. There was no significant difference between the numbers of robins detected in the Douglas fir (1.14 5 min count-1), or kanuka-manuka forest (0.86 5 min count-1), and no robins were detected in the Monterey pine forest. Kanuka-manuka forest had the greatest biomass and species richness of leaf-litter invertebrates, but the lowest evenness. We believe that the abundance of the South Island robin can not be sufficiently explained by the density or directly of leaf-litter invertebrates.
Collections of bird specimens assembled by T.F. Cheeseman’s family in the late 1800s and early 1900s, are well-documented as to collecting localities and dates of collection. They provide a record of bird-life in the Auckland, New Zealand, region at that time. An inventory of the Auckland specimens is given, as well as information on 2 of Cheeseman’s siblings: William Joseph Cheeseman, who collected (i.e. shot) birds; and Emma Cheeseman, who prepared study skins. Of greatest interest among the bird specimens are species no longer present at the localities near Auckland city at which they were collected, including brown kiwis (Apteryx mantelli) at Waitakere (1881), brown teal (Anas chlorotis) at Ellerslie (1878) and Remuera (1880, 1886), fairy terns (Sterna nereis) at Orakei (1878), kokako (Callaeas wilsoni) at Titirangi (1878), and fernbirds (Bowdleria punctata) (1878) and pipits (Anthus novaeseelandiae) (1887) at Remuera. It would be very unusual to see black-fronted terns (Sterna albostriata) at the Manukau Harbour (recorded in 1879), and black stilts (Himantopus novaezelandiae) at Mangere (recorded in 1879) today.
Introduced mallards (Anas platyrhynchos) occur on many islands of the South Pacific, where they hybridise with the resident grey duck (A. superciliosa). In October 2007, we conducted systematic surveys of Lord Howe Island to estimate the abundance and distribution of grey ducks, mallards, and their hybrids. Hybrids were common in areas of high public use, particularly where there was mown or grazed grass. Phenotypic characteristics suggest that mallards are now dominant and have supplanted the native grey duck, with 81% of birds classified as mallard or mallard-like hybrids, 17% as intermediate hybrids and only 2% as grey duck-like hybrids. No pure grey duck were observed. These hybrids pose direct and indirect economic, social and environmental impacts to Lord Howe Island. A management program to remove mallards using trapping, shooting and opportunistic capture by hand was conducted in October 2007. Standardised indices of duck abundance before and after management indicates that the total population was reduced by 71.7%. Eradication of mallard and hybrids from Lord Howe Island is considered achievable with a program of education, monitoring, and continued control to prevent re-establishment.
We collected and collated more than 2400 records of the rock wren Xenicus gilviventris, covering the period 1912-2005. These records allowed past and present distribution patterns to be mapped and compared. Areas from which birds have apparently disappeared were identified. The rock wren was common once on mountain ranges along or close to the Southern Alps, South Island, New Zealand, but have been recorded less frequently in many areas after 1980. More numerous records from some areas and during some decades could have resulted from differences in search effort and from inconsistency in record keeping. Nevertheless, there were consistent anecdotal accounts of decline, evidence of predation by stoats and mice, unsuccessful searches in previous strongholds and the recent extinction of 5 confamilial species indicate that the rock wren should be regarded as a threatened species.
Thirty-four species of birds are recorded from the isolated Pacific island of Nauru. Six are treated as hypothetical pending corroboration; 3 others are introductions. Eighteen of the 25 indigenous species are non-breeding visitors (mainly migrating seabirds and shorebirds). The 7 confirmed or probable resident breeders include only 2 land birds, the Micronesian pigeon (Ducula oceanica) and the endemic Nauru reed-warbler (Acrocephalus rehsei). The Australian pelican (Pelecanus conspicillatus) and white-winged tern (Chlidonias leucopterus) are reported as first records for Nauru. Hunting pressure and habitat degradation have contributed to reduced numbers of the Micronesian pigeon and the once abundant black noddy (Anous minutus), but the Nauru reed-warbler occurs commonly in degraded and modified habitats. Second-stage mining to recover phosphate deposits will likely reduce available habitat further for all resident breeding species, although land restoration is also planned. Bird band recoveries indicate that many seabirds, especially black noddies, reach Nauru thousands of kilometres from where they were fledged, but to what extent they are recruited into the local breeding population is unknown.
Male and female South Is saddlebacks (Philesturnus carunculatus carunculatus) have monomorphic plumage characteristics and are not easily distinguishable. In this study, we developed discriminant functions to classify males and females using birds of known sex from Ulva I. Three discriminant functions using tarsus length, body mass, and a combination of tarsus length and body mass could classify birds with 90% accuracy.