|Scientific Name:||Anas nesiotis|
|Species Authority:||(Fleming, 1935)|
|Taxonomic Notes:||Anas aucklandica (Sibley and Monroe 1990, 1993) has been split into A. aucklandica, A. chlorotis and A. nesiotis following Daugherty et al. (1999).|
|Red List Category & Criteria:||Endangered D ver 3.1|
|Contributor(s):||Gummer, H., McClelland, P. & Williams, M.|
|Facilitator/Compiler(s):||Benstead, P., Bird, J., Butchart, S., McClellan, R., Pilgrim, J., Symes, A., Taylor, J.|
This species is listed as Endangered because it has an extremely small population, which is nevertheless increasing thanks to successful conservation efforts. The species remains susceptible to external threats, and any evidence of a renewed decline is likely to make the species eligible for uplisting.
|Range Description:||Anas nesiotis is endemic to New Zealand, where it had been confined to Dent Island, an offshore islet of Campbell Island, for many decades. It was first collected in 1886 from the sea near Campbell (just 3 km away from Dent and likely to have been a stronghold for the species), but was not discovered on Dent until 1975. In 1990, a survey of Dent estimated a population of 60-100 birds (Goudswaard 1991), and it is likely that no more than 25 breeding pairs were present in 1998 (Gummer and Williams 1999). In 1999 and 2000, 24 captive-bred birds were released on Codfish Island to create a temporary population, and egg-laying occurred in their first year (Gummer and Williams 1999, Gummer 2006b). Following the successful eradication of brown rat Rattus norvegicus from Campbell Island in 2001, birds were taken back from Codfish Island for release in 2004 (50), 2005 (55) and 2006 (54) (Potter 2006, P. J. McClelland in litt. 2012, www.doc.govt.nz). The majority of birds released in 2004 were believed to have survived their first year on Campbell Island, and successful breeding was confirmed in 2006 when a brood of ducklings were seen in January, followed by sightings of a duckling, three juveniles and two nests containing eggs in February 2006 (Anon 2006). A survey in December 2008 confirmed that the species has established on the island (P. J. McClelland in litt. 2008, 2010, 2011), and the total population (captive and wild) has climbed to more than 200 individuals (Potter 2006). The 2008 survey, along with opportunistic observations of breeding and dispersal activity (P. J. McClelland in litt. 2008, 2010, 2011), suggests that the population now includes between 100 and 200 mature individuals.|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Following a captive-breeding, reintroduction and translocation programme, the species is now thought to have exceeded 50 mature individuals for at least five years. Based on the numbers released, surveys and opportunistic observations of breeding and dispersal activity (P. McClelland in litt. 2011), the population probably includes between 100 and 200 mature individuals, equivalent to 150-300 individuals in total.|
|Habitat and Ecology:||It lives under thick, chest-high tussock (there are no pools or running water on Dent). It has been sighted over most of the island, but is probably more common below 100 m, and in damp areas. It has not been observed feeding on the island, but in captivity it feeds on amphipods, weevils, earthworms, seaweed and other insects. Birds released onto Codfish Island have been observed feeding on invertebrates in piles of rotting seaweed along the shore and foraging offshore at night (Gummer and Williams 1999). In captivity, females sometimes lay two clutches of between one and four eggs (Preddey 1995). Reintroduced males on Campbell Island hold territories. Birds have dispersed into open upland areas, Dracophyllum forest, upstream habitats and coastal beaches (Gummer 2006a).|
|Major Threat(s):||Brown rats Rattus norvegicus on Campbell (one of the densest field populations in the world) may have caused its disappearance from this island (Williams and Robertson 1996). The successful eradication of this invasive alien species in 2001 has allowed the reintroduction of teal from captive stock. However, accidental reintroduction of rats, severe weather events and the introduction of avian disease remain possible threats. Brown Skua Catharacta lonnbergi, Kelp Gull Larus dominicanus, and Northern Giant-petrel Macronectes halli are potential natural predators (P. J. McClelland in litt. 2008, 2010, 2011).|
Conservation Actions Underway
CITES Appendix I. In 1998, 35 individuals were held in captivity (M. Williams in litt. 1999), originating from seven males and three females caught in 1984 and 1990, but nearly all have now been released onto Codfish Island with only around 20 birds retained as an insurance population (P. J. McClelland in litt. 2008, 2010, 2011). R. norvegicus was successfully eradicated from Campbell Island by 2003 during the world's largest rat eradication programme (BBC 2003, Seddon and Maloney 2003, Gummer 2006b). Birds have been successfully reintroduced to Campbell from the temporary Codfish Island population (M. Williams in litt. 1999, Anon 2006, Gummer 2006a, 2006b, Potter 2006). A survey of Campbell Island was carried out in December 2008, confirming that the population had established itself (P. J. McClelland in litt. 2008, 2010, 2011). All released birds have been screened for disease, but have so far not shown any negative signs (P. J. McClelland in litt. 2008, 2010, 2011). A monitoring expedition to Campbell Island is intended for summer 2013 (P. McClelland in litt. 2012).
Conservation Actions Proposed
Continue to monitor population trends. Continue to track the fate of released birds. Maintain the wild population and develop the captive breeding population. Establish additional wild populations. Exclude R. norvegicus from Campbell. Monitor the health of birds in all sub-populations to ensure that they are not suffering from disease.
|Citation:||BirdLife International 2013. Anas nesiotis. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 23 October 2014.|
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