Justification This species qualifies as Critically Endangered as it has had a tiny breeding population for many years. The one wild population on Dent Island off Campbell Island is assumed to have been stable. Recent reintroduction of birds to Campbell Island appears to have successfully established a second population, and overall numbers are now above the threshold for listing as Critically Endangered, and increasing. However, this classification will be retained for five years until the species is confirmed to be self-sustaining in larger numbers in the wild, at which time it will warrant downlisting.

Family/Sub-family Anatidae

Species name author (Fleming, 1935)

Taxonomic source(s) Daugherty et al. (1999)

Taxonomic note Anas aucklandica (Sibley and Monroe 1990, 1993) has been split into A. aucklandica, A. chlorotis and A. nesiotis following Daugherty et al. (1999).

Identification 48 cm. Small, flightless, dark brown duck. Brown eclipse male, female and juvenile. Mottled dark brown breast. Prominent white eye-patch. Breeding male has glossy green head. Very narrow white collar, flank patch. Voice Soft, high-pitched wheezy whistles and popping (male), low quacks and growls (female).

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

48 - 100

increasing

110 km²

Yes

Range & population 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 birds². It is likely that no more than 25 breeding pairs are present⁸. In 1999 and 2000, 24 captive-bred birds were released on Codfish Island, and egg-laying occurred in their first year^8,13. Following the successful eradication of Brown Rats Rattus norvegicus from Campbell Island in 2001, 50 teal were taken back for release on the island in September 2004 and a second batch of 55 were released in September 2005¹⁰. The majority of birds released in 2004 were believed to have survived their first year on Campbell Island. Successful breeding was confirmed on Campbell 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 2006¹¹, and although a planned survey in 2007/08 had to be postponed expectations are that this population is doing well¹⁴. The total population (captive and wild) has climbed to >200 individuals¹⁰.

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 night⁸. In captivity, females sometimes lay two clutches of between one and four eggs⁵. Reintroduced males on Campbell Island hold territories. Birds have dispersed into open upland areas, Dracophyllum forest, upstream habitats and coastal beaches¹².

Threats Brown rats Rattus norvegicus on Campbell (one of the most dense field populations in the world) may have caused its disappearance from this island⁶. However, 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 predators¹⁴.

Conservation measures underway CITES Appendix I. In 1998, 35 individuals were held in captivity⁷, 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 backup¹⁴. R. norvegicus was successfully eradicated from Campbell Island during the world's largest rat eradication programme^9,13. Birds have been successfully reintroduced to Campbell from the temporary Codfish Island population^{7,10,11,12,13}. A survey of Campbell Island was planned for the season 2007/08 but had to be postponed and is due to be carried out in 2008/09¹⁴. All released birds have been screened for disease, but have so far not shown any negative signs¹⁴.

Conservation measures proposed Continue to monitor population trends. Continue to track the fate of released birds. Maintain wild 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.

References 1. Daugherty et al. (1999). 2. Goudswaard (1991). 3. H. Gummer in litt. (1999). 5. Preddey (1995). 6. Williams and Robertson (1996). 7. M. Williams in litt. (1999). 8. Gummer and Williams (1999). 9. BBC (2003). 10. Potter (2006). 11. Anon (2006). 12. Gummer (2006a). 13. Gummer (2006b). 14. P.J. McClelland in litt. (2008).

Further web sources of information

Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

New Zealand Govt - Dept of Conservation - Recovery Plan

Text account compilers Phil Benstead (BirdLife International), Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Rachel McClellan (BirdLife International), John Pilgrim (BirdLife International), Andy Symes (BirdLife International)

Contributors Helen Gummer (Department of Conservation), Pete J McClelland (Department of Conservation), Murray Williams (Department of Conservation)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Andy Symes (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Anas nesiotis. Downloaded from http://www.birdlife.org on 10/2/2010

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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