Anas chlorotis 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Anseriformes Anatidae

Scientific Name: Anas chlorotis
Species Authority: Gray, 1845
Common Name(s):
English Brown Teal
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.
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).

Identification information: 48 cm. Small, dark brown duck. Brown eclipse male, female, juvenile. Mottled, dark brown breast. White eye-ring. Breeding male, glossy green head. Very narrow white collar. White flank patch. Similar spp. Grey Teal A. gracilis, Chestnut Teal A. castanea have a white triangle in front of speculum when in flight and no white eye-ring. Voice Soft, high-pitched wheezy whistles, popping (male), low quacks and growls (female).

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2015
Date Assessed: 2015-10-01
Assessor(s): BirdLife International
Reviewer(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. & Ashpole, 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. It no longer has a very small range, the species’s extent of occurrence (EOO) and area of occupancy (AOO) are no longer continuing to decline, it is present at approximately seven locations and the population has been increasing since 2003, following the establishment of new populations. The number of mature individuals is thought to be >1,000. The species therefore qualifies as Near Threatened as it almost qualifies for a threatened listing under criterion D1+2.

Previously published Red List assessments:
2012 Endangered (EN)
2008 Endangered (EN)
2007 Endangered (EN)
2006 Endangered (EN)
2004 Endangered (EN)
2000 Endangered (EN)
1994 Not Recognized (NR)
1988 Not Recognized (NR)

Geographic Range [top]

Range Description: This species 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 approximately 800 birds in 2013 (Hayes 2013), 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 latest estimate for the Northland population is approximately 500 individuals (Hayes 2013). The re-introduced population in the northern Coromandel numbered c. 500 individuals in early 2008, and the latest census in 2011 estimated the population at 1,000 individuals (Hayes 2013). 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). The re-introduced population at Cape Kidnappers is now estimated to number c. 135 birds (Booth 2011). By 2010, an estimated 1,700 birds were present at the three main sites (Great Barrier Island, Northland and Coromandel) and including the newly established populations, this figure was suggested to be in excess of 2,000 in 2010 (A. Booth et al. in litt. 2012). By 2013 the total number of birds was estimated at approximately 2,500 (Hayes 2013).

Countries occurrence:
New Zealand
Continuing decline in area of occupancy (AOO): No
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 940
Continuing decline in extent of occurrence (EOO): No
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 7
Continuing decline in number of locations: No
Extreme fluctuations in the number of locations: No
Range Map: Click here to open the map viewer and explore range.

Population [top]

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 numbered c. 1,900 individuals or c. 1,300 mature individuals, based on the assumption that they account for around 2/3 of the total population. By 2010, an estimated 1,700 birds were present at the three main sites (Great Barrier Island, Northland and Coromandel) and including the newly established populations, this figure was suggested to be in excess of 2,000 in 2010 (A. Booth et alin litt. 2012). By 2013 the total number of birds was estimated at approximately 2,500 (Hayes 2013), equating to 1,700 mature individuals.

Trend Justification:  The population had been falling rapidly owing to predation by introduced mammals; however, since 2003 it has been increasing as a result of intensive management. The rate of increase has not been estimated.
Current Population Trend: Increasing
Additional data:
Number of mature individuals: 1700 Continuing decline of mature individuals: No
Extreme fluctuations: No Population severely fragmented: No
No. of subpopulations: 7 Continuing decline in subpopulations: No
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

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. 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). It feeds on terrestrial, freshwater and marine invertebrates and terrestrial and freshwater vegetation (Williams and Dumbell 1996, Moore et al. 2006). Often nocturnal (del Hoyo et al. 1992).

Systems: Terrestrial; Freshwater; Marine
Continuing decline in area, extent and/or quality of habitat: No
Generation Length (years): 6.6
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): 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 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 [top]

Conservation Actions: Conservation and Research 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. 

A captive breeding programme was initiated in 1973, founded by 22 birds (Bowker-Wright et al. 2012). 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). To date, new populations derived from captive birds have been established at: Mana Island, Kapiti Island, Tiritiri Matangi Island, Karori Wildlife Sanctuary and Moehau (where a small remnant wild population was supplemented by captive birds) (Bowker-Wright et al. 2012). 

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). Predator control programmes and release of captive-reared birds has taken place at Northland (Hayes 2013). Research is on-going, focusing on management techniques and habitat requirements (Williams and Dumbell 1996).

Conservation and Research 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. A recent study indicated that the range of genetic diversity present in the wild populations was not reflected in the captive population (Bowker-Wright et al. 2012, Williams and Bowker-Wright 2013). Supplementing the captive population or renewing the breeding stock to ensure the full genetic diversity found in the wild population is represented in captive birds should be considered as well as introducing genetic diversity into all new populations (Bowker-Wright et al. 2012). A genetic analysis indicates that the species once inhabited forested habitats and their current habitat of estuarine and riparian areas may represent only a small part of the species's potential habitat (Holdaway et al. 2013). The researchers suggest that work is needed to evaluate whether the species is capable of surviving in forested habitats.

Citation: BirdLife International. 2015. Anas chlorotis. The IUCN Red List of Threatened Species 2015: e.T22728303A83275138. . Downloaded on 30 November 2015.
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