The shore plover (Thinornis novaeseelandiae) is a highly threatened shorebird endemic to New Zealand. It is particularly susceptible to introduced mammalian predators, and has a very small total population and a very limited range. This paper lists the translocations that have formed the core of the shore plover recovery programme over the past 22 years, and summarises the outcomes. In the early 1990s, a captive population was established in mainland New Zealand using birds reared from eggs transferred from the last self-sustaining wild population on the Chatham Islands. Since 1994, captive-bred birds have been released on 5 offshore islands around the New Zealand mainland in attempts to found new populations. There have also been transfers of wild-bred birds from South East I to Mangere I in the Chatham Is. Between 1994 and April 2012, 404 juvenile and 28 adult shore plover have been released at a total of 6 sites. Birds bred at 4 of the 6 sites, and breeding populations established at 3 of them. However, recent mammalian predator incursions at 1 (and probably 2) of those, and habitat limitation at the 3rd, mean that the translocated populations are all currently small (6 pairs or less), and their long-term future is uncertain. Other challenges faced during the programme include avian predation of released birds, high rates of dispersal, and outbreaks of avian pox. In spite of recent setbacks, the risk of extinction for the species has gradually been reduced. Since 1990, a self-sustaining captive population has been set up, the number of breeding pairs has increased, and the number of breeding populations in the wild has risen from 2 to 4 (although 1 is currently facing extirpation). Features of the shore plover programme that have contributed to these outcomes are outlined. Aspects of shore plover ecology revealed by the translocations are noted. While progress has been made, existing populations will need to grow, and further populations will need to be established before the shore plover’s threat ranking improves.
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.
Transfers of North Island robin (Petroica longipes) and North Island tomtit (P. macrocephala toitoi) were undertaken from various sites around the Wellington region to within the mammal-proof fence at the Zealandia-Karori Sanctuary from 2001-2004. Differing methodologies were trialled to test translocation protocols for these species. Robin translocations (34 males and 42 females from Kapiti I translocated in 2000 and 2001) were straightforward and robins established in the sanctuary despite the fence not being a physical barrier to dispersal. They bred from the first season and numbers have since increased rapidly. Tomtits were transferred from 2 source populations (Kapiti I and Akatarawas; 39 males and 12 females over 4 years from 2001-2004) but failed to establish. To hold tomtits in an aviary and avoid aggression it was necessary to keep sexes apart. Although successful tomtit breeding was observed both within and outside the sanctuary, predation pressure was higher outside the sanctuary. A progressive move of tomtit territories out of the sanctuary may have been a response to increasing aggression from the expanding robin population.