Bone samples from 2 surviving populations of New Zealand’s endemic and endangered brown teal (Anas chlorotis) had a much smaller distribution of stable isotopic values (δ13C, δ15N) than those from Holocene-age fossil bones of the same species. Comparison with δ13C and δ15N values from 2 other taxa of known ecologies indicated that some brown teal were forest floor omnivores. The results indicate that the riparian and estuarine wetlands occupied by present natural populations represent only an extreme, truncated part of the species’ potential habitat. To aid present conservation efforts we suggest that brown teal be released into forested areas and islands managed as mammal-free enclaves to test whether modern birds can survive in habitats once occupied by now-extirpated populations. Palaeoecological studies, including stable isotope analyses, can be used to identify conservation options not obvious from research on declining remnant populations in anthropogenic environments.
A number of studies have found that birds in urban areas alter singing behaviour, possibly to increase signal transmission and avoid masking by high levels of anthropogenic background noise. However, few studies have focused on how these song differences might be interpreted by receivers. We investigated differences in song between populations of urban and rural Australian magpies (Gymnorhina tibicen), an Australian species abundant in both habitats. First, we compared urban and rural magpie songs to determine if magpies shift the frequency, duration and output of songs in response to anthropogenic noise. Unlike some songbirds, urban magpies did not shift minimum frequencies to avoid masking, however they did sing shorter songs. We then played back unfamiliar urban and rural songs to groups of both urban and rural magpies, and monitored their territorial responses. Results showed that differences in song across both habitats do not affect receiver responses, indicating that magpies from both urban and rural habitats can readily communicate with each other. Interestingly, rural magpies responded with more aggression to rural songs than to either urban songs or to control songs. We propose that the flexibility of Australian magpie songs aids this species in its ability to adapt successfully to urban environments.
A unique Pterodroma petrel shot at sea near the Antipodes Islands in 1926 has features intermediate between white-headed petrel (Pterodroma lessonii) and soft-plumaged petrel (Pt. mollis). Its mitochondrial DNA indicates that its mother was a Pt. mollis and we conclude that it is a hybrid. We theorise that Pt. mollis had begun colonising Antipodes Island by the 1920s and some pairing with the locally abundant congeneric Pt. lessonii occurred. Hybridisation in Procellariiformes is rare worldwide but several cases have now been reported from the New Zealand region.
Deliberate taxon substitution is a much discussed but rarely enactioned concept in restoration ecology. We describe the successful establishment of a translocated population of Snares Island snipe (Coenocorypha huegeli) on Putauhinu I, which lies alongside Taukihepa (Big South Cape I), the last stronghold of the extinct South Island snipe (C. iredalei). Thirty Snares Island snipe were captured on North East I, Snares Is in Apr 2005 and released 3-5 days later on Putauhinu I. A survey on Putauhinu I in Mar 2011 resulted in the capture of 54 descendants of the released birds and a population estimate of at least 320 birds. This is one of few documented translocations of an organism with the specific objective of replacing a closely related extinct taxon. As a result, the Snares Island snipe is probably more abundant than at any time in its evolutionary history.
To date there has been no published information describing the relative abundance, behaviour or distribution of the New Zealand king shag (Leucocarbo carunculatus) within mussel farm areas, despite the sensitivity of the species to human disturbance and the potential overlap of its range with proposed development of marine aquaculture. Four survey methods were employed as part of a multi-species research programme to develop methods for surveying marine mammals and seabird populations in aquaculture management areas. Two of the techniques, involving continuous time- lapse photography of mussel farms and boat-based surveys through coastal farms were developed for this study. Time- lapse cameras showed that mussel farms buoys were used by king shags as temporary resting sites only. King shags were recorded on 36% of the farms (n = 44) from 13 surveys within inner Admiralty Bay. The low number of sightings within mussel farms suggests that farms are not important foraging or resting areas for king shags, at least in Admiralty Bay. The foraging range and density of king shags was not known before farms were developed, so no direct comparison or impact assessment can be made. Boat-based surveys were used to estimate the density of foraging shags, which showed that daily locations of foraging birds at sea can vary considerably on consecutive days and over the season. Previous environmental surveys to assess impacts of mussel farms on foraging areas are therefore unlikely to adequately represent the entire foraging range or most important feeding areas. The number of breeding pairs, chicks and nests was also found to vary considerably at colonies, dependent on when counts were undertaken during their protracted breeding season. Open water mid-bay aquaculture (shellfish and finfish) potentially poses a greater threat to king shags than ‘coastal ribbon development’, in terms of loss of open water habitat from farm structures, and loss of foraging habitat through modification to the water column (e.g., turbidity) and seabed. Given the lack of knowledge about the king shag population dynamics, diet and prey availability, there is an urgent requirement for more research to fill these gaps and also understand how we can conserve important shag feeding areas and associated marine environment through sustainable management of aquaculture.
The South Island snipe (Coenocorypha iredalei) was described by Walter Rothschild in 1921 based on 3 specimens collected on Jacky Lee I, off Stewart I, in 1897 & 1898 and purchased from Henry Travers. The last 3 birds were seen 43 years later on Big South Cape I, and the species is considered extinct following introductions of weka (Gallirallus australis) or ship rats (Rattus rattus) to its 2 last strongholds. I surveyed surviving museum skins, literature, and personal accounts of the South Island snipe, including a previously unpublished account from the type locality, to learn more of the bird’s discovery and extinction. Seven only of the 24 known specimens had correct locality data associated with them; as a result, many were assumed until recently to be Snares Island snipe (C. huegeli). Based on specimen records, historic correspondence, and forensic examination of specimen labels, I conclude that Henry Travers never visited Jacky Lee I, and that the unknown collector of the type specimens of C. iredalei also collected bird specimens from Rangatira I in the Chatham Is in 1899 and 1900.
Sexual differences in vocalisations of the Vanuatu petrel (Pterodroma occulta) are described. Qualitative differences in burrow calls could be used to sex adults with 63-100% accuracy in listening experiments. Males sounded “clear” and females sounded “hoarse”. Higher accuracy is possible with the aid of spectrograms. Playback experiments demonstrated a male-bias in responses of incubating Vanuatu petrels to “war-whooping” and flight calls. Acoustic methods have practical and ethical advantages over handling breeding petrels and further studies of the vocal behaviour of gadfly-petrels are encouraged.
Edgar Stead (1881-1949) documented avian diversity on the islands around Stewart I during the 1930s and 1940s, and named 3 new passerine subspecies in 1936. Between 1912 and 1950, 6 other newly-recognised bird taxa were given the epithet ‘steadi’. Four of these were indisputably named after Edgar Stead: Stictocarbo steadi Oliver, 1930, Pseudoprion turtur steadi Mathews, 1932, Thalassarche cauta steadi Falla, 1933, and Petroica (Miro) australis steadi Fleming, 1950. Carbo carbo steadi Mathews & Iredale, 1913 was probably named after Edgar Stead. It is suggested that Procellaria aequinoctialis steadi Mathews, 1912 was most likely named after the Australian naturalist David Stead (1877-1957). Among the birds named by or for Edgar Stead, only Thalassarche cauta steadi Falla, 1933, Xenicus longipes variabilis Stead, 1936, and Bowdleria punctata wilsoni Stead, 1936 are recognised as valid taxa in the 2010 Checklist of the birds of New Zealand. Stictocarbo steadi Oliver, 1930 is permanently invalid. A list of type specimens collected by Stead is presented, representing 6 currently recognised taxa.