Overview

Brief Summary

Biology

Brown teal are a nocturnal dabbling duck that hides in grass and overhanging vegetation during the day, and forages in fields for worms and insects, or in estuaries for small shellfish at night. It will also sieve through muddy pools and even search through cow dung for invertebrates (4). In the non-breeding season, the brown teal is social, forming small groups at roost sites. However, during the breeding season, from July to November, pair bonds are formed or re-established and both partners behave very aggressively to defend their territory, occasionally killing invading teals. A nest is built in thick vegetation close to water, in which the female lays five or six eggs, incubating them for 27 – 30 days. The ducklings fledge at 55 days, but will remain with their family until the following breeding season. Adults moult shortly after the ducklings have hatched, migrating to a flock site when the moult is complete (4).
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Description

In breeding plumage, the male ducks have a chestnut-coloured breast, a green head and a white stripe down both sides of the body. Some also have a white neckband. However, in non-breeding plumage, males look identical to females and juveniles, with non-descript mottled brown feathers, although males are slightly larger (4). Males utter soft, high-pitched whistles and pops, whereas females emit low quacks and growls (2).
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Distribution

Range Description

This speciesis 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).

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Range

New Zealand and offshore islands.
  • Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2014. The eBird/Clements checklist of birds of the world: Version 6.9. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/

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Range

Once found throughout the lowland, freshwater wetlands of New Zealand and several offshore islands, the brown teal is now limited to Great Barrier Island, and the east coast of Northland, south of the Bay of Islands. Numbers currently stand at around 1,000 (4). Reintroductions of captive-reared juveniles to Coromandel over four years has resulted in the establishment of a resident breeding population (5). Small populations are also found on Little Barrier Island, Rakitu Island, Kawau Island, Moturoa Island, Tiritiri Matangi Island and Kapiti Island, mainly due to reintroductions (4).
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Ecology

Habitat

Habitat and Ecology

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, Mooreet al. 2006). Often nocturnal (del Hoyo et al. 1992).


Systems
  • Terrestrial
  • Freshwater
  • Marine
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The brown teal previously inhabited a diverse selection of freshwater wetlands and swamp-forest, particularly in the lowlands, but it is now found only in coastal streams, wetlands and dams near to farmland. It nests in grass bowls under thick vegetation (2). Fossil evidence even suggests that the brown teal was once found in forested areas, far from wetlands (4).
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
NT
Near Threatened

Red List Criteria

Version
3.1

Year Assessed
2015

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.

Justification
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 speciess 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.


History
  • 2012
    Endangered (EN)
  • Endangered (EN)
  • Endangered (EN)
  • Endangered (EN)
  • Endangered (EN)
  • Endangered (EN)
  • Not Recognized (NR)
  • Not Recognized (NR)