|Scientific Name:||Thinornis novaeseelandiae|
|Species Authority:||(Gmelin, 1789)|
|Red List Category & Criteria:||Endangered D ver 3.1|
|Reviewer(s):||Butchart, S. & Symes, A.|
|Contributor(s):||Aikman, H., Askew, N., Dowding, J., Hitchmough, R., Miskelly, C., O'Connor, S. & Szabo, M.|
|Facilitator/Compiler(s):||Benstead, P., Butchart, S., Harding, M., Khwaja, N., Mahood, S., McClellan, R., Taylor, J.|
This species is classified as Endangered because it has an extremely small population. Translocated populations may not be sustainable. If habitat loss continues on its last island stronghold, and proves significant, it may require uplisting to Critically Endangered. However, recent data suggest that the population is now increasing and additional sub-populations are becoming established.
|Range Description:||Thinornis novaeseelandiae breeds on South East Island (= Rangatira) and Mangere Island (with vagrants to Pitt Island) in the Chatham Islands, New Zealand. A small population on Western Reef, Chatham Islands declined following its discovery, when 21 individuals were known (Bell and Bell 2000), and the last individual was taken into captivity in 2003. The species was once widespread around the coast of at least the South Island, but had been extirpated by the 1870s. In 1937, the population on South East Island was estimated at 72 pairs by Fleming. Since grazing ceased in the 1960s, inland pasture used for nesting has become overgrown, and the population has declined and become increasingly restricted to the coast (Department of Conservation 2001). It has stabilised at 45-50 pairs and a post-breeding total of 120-140 individuals (S. O'Connor per H. Aikman in litt. 1999, J. E. Dowding in litt. 2008, C. Miskelly in litt. 2008, S. O'Connor in litt. 2008). Releases on islands off mainland New Zealand have had mixed success. On Motuora Island, Hauraki Gulf, reintroduction was unsuccessful and the two remaining males were re-captured for use in the captive-breeding programme. At Release Site 2, off the east coast of the North Island, a population numbering 100 birds in 2007 was successfully established (Anon. 2006, J. E. Dowding in litt. 2008, C. Miskelly in litt. 2008, S. O'Connor in litt. 2008). Attempts to establish a population on Mangere Island, Chatham Islands, between 2001 and 2003 by the transfer of wild-bred juveniles from South East Island were also successful, and 6 pairs are now breeding; this is believed to be at or close to the carrying capacity of the island (O'Connor in litt. 2008, C. Miskelly in litt. 2008, J. E. Dowding in litt. 2008). In 2006, a single release was made at Release Site 3, an island off the South Island; further releases there were halted when birds were found to be carrying avian pox, and a population did not establish itself. In 2007, releases began on Mana Island, near Wellington. One pair bred and successfully fledged a chick in 2007-2008, and further releases occurred in 2008 (O'Connor in litt. 2008, C. Miskelly in litt. 2008, J. E. Dowding in litt. 2008, Anon. 2009). Five more young were fledged in 2009 (Anon. 2009). This programme of releases on Mana Island will run for five years with the aim of establishing a self-sustaining population (S. O'Connor in litt. 2008).|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The total mature population was estimated at about 200-220 birds in 2008, with the effective population numbering 156-166 birds (78-83 pairs), because the species is still limited by breeding habitat ( J. E. Dowding in litt. 2008, C. Miskelly in litt. 2008, S. O'Connor in litt. 2008). The total population was considered likely to number 300-330 individuals. Whilst it is now thought to number closer to 250 individuals (N. Askew in litt. 2009), these earlier estimates are retained pending confirmation.|
|Habitat and Ecology:||On South East Island, it nests at the head of rock wave-platforms, on salt meadows and on sandy and boulder beaches (J. E. Dowding in litt. 2008). It feeds on small crustaceans, molluscs and other invertebrates, using "foot-trembling and beak probing" behaviour (Heather and Robertson 1997, Armitage 2008). It lays two to three eggs in a nest set under dense vegetation, beach rack or boulders, either on the shore or further inland (Davis 1994, Heather and Robertson 1997). On South East Island, where the population is at carrying capacity, breeding usually begins in the second or third year. Breeding has occurred in the first year at reintroduction sites and in captivity, where resources are less limiting. In 1986, the average age of the population was six years (Dowding and Kennedy 1993, Davis 1994). The oldest known individual was a male aged 21 years (J. E. Dowding in litt. 2008).|
Cats and brown rats Rattus norvegicus probably caused its extinction from the South Island (Dowding and Kennedy 1993, Davis 1994). The removal of sheep from South East Island in 1961 has resulted in some loss of breeding habitat on the southern coast as previously grazed marsh-turf has reverted to forest. This threat is likely to continue, but is off less immediate concern. Other threats include fire, expansion of fur seal Arctocephalus forsteri colonies, disease, rough seas and storms, human disturbance and predation by Brown Skuas Catharacta skua (J. E. Dowding in litt. 1999, Department of Conservation 2001). Island visitors heighten these threats (Department of Conservation 2001). Losses from translocated populations have largely been the result of dispersal to the mainland (where they are killed by predators, although some birds have survived for several years before vanishing) and predation by Morepork Ninox novaeseelandiae (Aikman 1999) and Australasian Harrier was recorded on Motuora Island. The threat of mammalian predator reinvasion to offshore islands is a constant threat requiring vigilant contingency measures (J. E. Dowding in litt. 2008, S. O'Connor in litt. 2008). Mustelid (stoat, weasel or ferret) arrival on any Shore Plover islands would have devastating results (S. O'Connor in litt. 2008). These pests are common on mainland New Zealand.
Conservation Actions Underway
The population on Rangatira Island and all translocated populations are monitored annually, and research is on-going. Two captive populations are held to provide birds for translocations. Releases of captive-reared birds began on Motuora Island (71 individuals released in 1994-98); two chicks were successfully fledged, but the translocation failed due to predation by Moreporks (C. Miskelly in litt. 2008). The two last birds lingered on nearby Beehive Island until they were caught and returned to captivity in 2005. A breeding population of about 100 birds (27 pairs) was successfully established on another island off the North Island following releases of captive-reared birds between 1998 and 2005. The location of this privately-owned island is not divulged, at the request of the owners. A small breeding population of about 12 birds (five pairs) was established on Mangere Island (Chatham Islands) by transferring recently-fledged wild juveniles from nearby Rangatira Island during 2001-2003 (C. Miskelly in litt. 2008). This subpopulation is constrained by limited habitat, but interchange of individuals is occurring with the larger Rangatira population. Fifteen captive-reared juveniles were released on Rarotoka (Centre) Island in Foveaux Strait in March 2006, but all birds dispersed (C. Miskelly in litt. 2008). Further releases of wild (parent-reared) juveniles are planned for this site. Forty-one captive-reared birds (mainly juveniles) were released on Mana Island in March-May 2007, and one pair laid a two-egg clutch there in December 2007. One of the chicks fledged, and five more fledged the subsequent year (Anon. 2009). Further releases of captive-reared juveniles have been on-going as part of a five-year project (C. Miskelly in litt. 2008, Anon. 2009). Conservation Actions Proposed
Implement measures to detect the arrival of mammalian predators on South East Island and all release sites (J. E. Dowding in litt. 1999). Continue the captive-breeding and release programme at suitable sites around mainland New Zealand, and produce suitable literature on captive management and release techniques. Maintain habitat quality on South East Island, restrict the number of visitors, and monitor any environmental change (Department of Conservation 2001). Research species interactions with avian predators (owls, harriers, skua and gulls). In the longer term, remove cats and Weka from Pitt Island to allow expansion of the South East Island population.
|Citation:||BirdLife International 2012. Thinornis novaeseelandiae. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 28 August 2015.|
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