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Anas chlorotis 

Scope: Global
Language: English
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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, Barcelona, Spain and Cambridge, UK.
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: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
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., Ashpole, J & Stringer, C.
Justification:
Until recently this species' 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 >1,000. The species qualifies as Near Threatened as it almost qualifies for a threatened listing under criterion D1+2.

Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is endemic to New Zealand, where it was once widespread throughout the mainland and offshore islands (Worthy 2002). It occurred in the Chatham Islands until about 1925 and Stewart Island until about 1972 (Williams 2013). A. chlorotis is now largely restricted to northern North Island (Northland, Great Barrier Island, Coromandel Peninsula) but has been reintroduced to Kapiti and Mana Islands, Zealandia sanctuary near Wellington, and a private sanctuary in Cape Kidnappers, Hawke's Bay (Williams 2013). In 2011, minimum counts completed at stronghold sites were: Northland 408 (total estimate 600); Great Barrier Island 803 (total estimate 1,000); Coromandel Peninsula 321 (total estimate 400) (Department of Conservation 2011). This gave a total population estimate of 1,500-2,500 in 2011 (Williams 2013).


Countries occurrence:
Native:
New Zealand
Additional data:
Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:301000
Continuing decline in extent of occurrence (EOO):NoExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:7Continuing 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:Although once widespread and numerous, by the 1990s A. chlorotis populations were confined to two key strongholds, Great Barrier Island and Northland, with a remnant population in Fiordland and two very small (< 20 individuals) reintroduced populations on offshore islands (Williams & Dumbell 1996, Watts et al. 2016). By 2007 the population was limited to approximately 1,000 wild birds (O’Connor et al. 2007), with research indicating that the species was facing extirpation from mainland New Zealand (Parrish & Williams 2001) and showing that the population on Great Barrier Island was halving every 4.1 years (Ferreira & Taylor 2003).

In 2011 after a period of revised management (O'Connor et al. 2007), minimum counts completed at stronghold sites were: Northland 408 (total estimate 600); Great Barrier Island 803 (total estimate 1,000); Coromandel Peninsula 321 (total estimate 400) (Department of Conservation 2011). The total population of wild birds was estimated at 1,500-2,500 including all sites (Williams 2013) meaning there were approximately 1,000-1,600 mature birds assuming these made up two thirds of the total population.

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:1700Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:7Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:A. chlorotis formerly occurred in a wide range of habitats, including wet forests up to 800m, extensive and occluded swamps, slow-flowing streams, lakes and estuaries (Worthy 2002, Williams 2013). Their present day habitat lies mostly in agricultural environments wherein the birds use occluded stock ponds as breeding and feeding sites and also margins of small streams that retain overhanging marginal vegetation (Williams 2013). Some birds still feed in estuaries on Great Barrier Island.

A. chlorotis are monogamous and territorial. Most nesting is in late winter (July to September) but can occur throughout the year, except in late autumn. Nests are usually in dry locations such as the bases of rush, grass or fern clumps. Eggs are generally laid daily and the average clutch is five or six eggs (range 3-9). The incubation period lasts for around 28 days. Both parents guard the ducklings for the 50-55 days until fledging and the brood is generally raised within the territory (Williams 2013).

The majority of A. chlorotis aggregate in flocks at some times of year, although some pairs will remain on their territories at all times. Flocks arise from mid-summer aggregations of fledglings and early-moulted adults whose territories have dried out. Non-breeding birds may remain as a flock throughout winter and spring (Williams 2013). They are generally crepuscular to nocturnal in habit in agricultural and forested environments but at coastal sites their behaviour may also be influenced by tides, being more active at low tides (del Hoyo et al. 1992, Williams 2013).

Diet is diverse and may include terrestrial, freshwater and marine invertebrates, fungi, and terrestrial and freshwater vegetation (Williams and Dumbell 1996, Moore et al. 2006, Williams 2013).


.

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). 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, O'Connor et al. 2007, Sim and Roxburgh 2007). Habitat modification, drought-induced habitat change, traffic-induced road deaths, starvation and especially predation continue to endanger remnant mainland populations (Hayes 2006, O'Connor et al. 2007, Sim and Roxburgh 2007, Department of Conservation 2011, Watts et al. 2016). Predation by Australasian Harriers Circus approximans is now significant at some sites, accounting for more than half of deaths from predation on Great Barrier Island (Watts et al. 2016).

Conservation Actions [top]

Conservation Actions: Conservation and Research Actions Underway
The species is listed on 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 (O'Connor et al., 2007). Following a major audit of the recovery programme in 2000 and intensified predator control at key sites, the population has begun to increase (Hayes 2010, Watts et al. 2016) . 

Captive breeding was initiated in 1973, but initial mainland releases of more than 1,000 birds (Williams and Dumbell 1996) did not arrest declines. Releases are now conducted in combination with intensive predator control and breeding populations are established in several locations (Heather and Robertson 1997, Hayes 2006, O'Connor et al. 2007, Sim and Roxburgh 2007), with the Coromandel Peninsula becoming a new stronghold for the species (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, Zealandia Sanctuary, Cape Kidnappers, and Moehau  on the Coromandel Peninsula (where a small remnant wild population was supplemented by captive birds) (Bowker-Wright et al. 2012). The captive population has been restructured in response to research finding that it did not reflect the genetic diversity found in the wild population (Bowker-Wright et al. 2012, Williams and Bowker-Wright 2013, N. Miller in litt. 2016).

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)

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, especially investigation of diet and habitat use (Watts et al. 2016). 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. Investigate improvements to supplementary feeding regime after translocations (Rickett et al 2013).

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 potential habitat for this species (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. 2016. Anas chlorotis. The IUCN Red List of Threatened Species 2016: e.T22728303A94979035. . Downloaded on 10 December 2016.
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