|Scientific Name:||Anas chlorotis|
|Species Authority:||Gray, 1845|
|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 B1ab(iii) ver 3.1|
|Reviewer(s):||Butchart, S. & Symes, A.|
|Contributor(s):||Battley, P., Booth, A., Hayes, N., Holzapfel, A., Miller, N., Moore, S., Roxburgh, J. & Williams, M.|
|Facilitator/Compiler(s):||Benstead, P., Martin, R, Pilgrim, J., Taylor, J.|
This species has a very small range. Until recently its overall range, area of occupancy, area and quality of habitat, number of locations and sub-populations, and number of individuals were undergoing very rapid declines; however, intensive management has halted the decline and populations are now increasing, with several new populations being established. Despite this recent change in fortunes, it remains classified as Endangered until these trends are consolidated.
Anas chlorotis is endemic to New Zealand, where it was once widespread in the North, South, Stewart and Chatham Islands, but its range is now much reduced. The current strongholds are on Great Barrier Island, where there were 1,300-1,500 birds in the early 1990s, declining to little over 500 in the early 2000s and increasing to over 600 in 2004, and at Mimiwhangata and Teal Bay on the east coast of Northland where the population declined by 65% in the period between 1988 and 1999 to c.100 individuals in 2001 before increasing to nearly c.350 by 2007 (Williams and Dumbell 1996, M. Williams in litt. 1999, Parrish and Williams 2001, Roxburgh 2005, S. Moore and P. Battley in litt. 2012). The re-introduced population in the northern Coromandel numbered c.500 individuals in early 2008, and is increasing. Its estimated Area of Occupancy is only c.300-500 km2 (Callaghan et al. in prep). After a study on Great Barrier Island indicated that the population was halving every 4.1 years and could rapidly decline to extinction intensive management was initiated which has seen populations rising again (Ferreira and Taylor 2003, Roxburgh 2005, Hayes 2006, Sim and Roxburgh 2007). Small islands where birds have previously been introduced and persisted for one to two decades may be too small for long-term survival, and some of these populations appear to be approaching extinction; however, the overall population trend is now positive (M. Williams in litt. 1999, Roxburgh 2005, Sim and Roxburgh 2007). New populations have been established at Tawharanui, Cape Kidnappers and Tuhua Island (A. Booth et al. in litt. 2012); however, for the purposes of this assessment, the number of locations is treated as three, until the long-term outcomes of releases beyond Great Barrier Island, Northland and Coromandel can be judged with confidence.
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Over 1,100 birds were estimated in 2005 at Great Barrier Island and Northland alone (with c.600 at each) (A. Booth et al. in litt. 2012, N. Hayes in litt. 2012), and the population on Coromandel has been estimated at c.700 birds (N. Hayes in litt. 2012), suggesting that the population numbers c.1,900 individuals, treated here as including c.1,300 mature individuals, based on the assumption that they account for around 2/3 of the total population.|
|Habitat and Ecology:||It formerly occurred in a wide range of habitats, including freshwater and coastal wetlands, and inland forests up to 800 m (Worthy 2002). It is now restricted to coastal streams, wetlands and dams in predominantly agricultural environments (M. Williams in litt. 1999). It nests in bowls of grass, always under dense, low vegetation, and usually lays six eggs. It feeds on terrestrial, freshwater and marine invertebrates and terrestrial and freshwater vegetation (Williams and Dumbell 1996, Moore et al. 2006). Peak breeding takes place between May and September, but can occur throughout the year (Sim and Roxburgh 2007). Only the female incubates the eggs (Sim and Roxburgh 2007).|
|Systems:||Terrestrial; Freshwater; Marine|
Between the 1890s and 1930s, wetland drainage and severe hunting pressure (which continued in several areas despite legal protection in 1921) caused widespread local extinctions (Heather and Robertson 1997, Callaghan et al. in prep). Predation by the introduced mammalian predators, primarily cats, dogs, mustelids Mustela spp. and possums Trichosurus vulpecula, as well as the native Purple Gallinule Porphyrio porphyrio (locally known as Pukeko), were the primary cause of the modern decline (Heather and Robertson 1997, Ferreira and Taylor 2003, Hayes 2006, Conner et al. 2007, Sim and Roxburgh 2007). Habitat modification, drought-induced habitat change, traffic-caused road deaths and especially predation continue to endanger remnant mainland populations (M. Williams in litt. 1999, Parrish and Williams 2001, Hayes 2006, O'Connor et al. 2007, Sim and Roxburgh 2007). The threat of habitat loss to agriculture has diminished to some extent in recent years (N. Hayes in litt. 2012).
Conservation Actions Underway
CITES Appendix I. In 2007, a species recovery plan was produced with the goal of securing in the wild a combined protected population of 2,000 birds at 5-10 managed sites by 2010. Following a major audit of the recovery programme in 2000 the population has begun to increase. Over 200 birds are held in captivity. Although initial mainland releases totalling over 1,000 birds (Williams and Dumbell 1996) failed, releases are now conducted in combination with intensive predator control and breeding populations appear to have become established in several locations (Heather and Robertson 1997, Hayes 2006, O'Connor et al. 2007, Sim and Roxburgh 2007), and that the species's total population is entering a recovery phase (Hayes 2010, A. Booth et al. in litt. 2012). At least 139 individuals have now been released in a predator-controlled area of Fiordland on the South Island with the hope of establishing a population (Anon. 2011). Predator control, including that of Purple Gallinule (Pukeko), on Great Barrier Island has also led to stability in this population (Hayes 2010). Hazing fences on roads have been erected to force ducks to either fly or use culverts when passing between favoured feeding sites, these have met with success and are planned for more areas (Hayes 2006, Sim and Roxburgh 2007). Habitat is being restored in Northland and Coromandel with the co-operation of local landowners, and some wetlands are grazed to create improved conditions for teal (Sim and Roxburgh 2007). Research is on-going, focusing on management techniques and habitat requirements (Williams and Dumbell 1996). Conservation Actions Proposed
Continue to implement the species recovery plan. Continue to maintain a viable breeding population at a minimum of two locations on the North Island mainland. Continue measures to increase the population on Great Barrier Island. Continue predator control measures at key sites. Erect more hazing fences in areas where road mortality is greatest. Continue the captive breeding programme as a source of birds for translocations. Continue to encourage public support and involvement (Williams and Dumbell 1996). Conduct research into seasonal starvation events (A. Booth et al. in litt. 2012). Carry out studies into habitat use by the species. Conduct research into causes of declines.
|Citation:||BirdLife International 2012. Anas chlorotis. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 05 July 2015.|