Brown Teal / Pateke

T A X O N O M Y

Vernacular name: Brown Teal, pateke
Scientific name: Anas chlorotis
Family/Subfamily: Anatinae (Ducks)
Order: Anseriformes
Class: Aves

C O N S E R V A T I O N S T A T U S

New Zealand status: Endemic

DOC Status: At Risk – Recovering

IUCN Status: Vulnerable

Brown teal are endemic to New Zealand and, in pre-human times, may have been the most widespread and numerous of New Zealand’s waterfowl. The brown teal was an abundant and widespread species 200 years ago, but became highly endangered due mainly to the impacts of introduced predators.

IDENTIFICATION

Both sexes of brown teal are darkish brown, but they are sexually dimorphic in plumage and size. Both sexes have a conspicuous white eye ring, dark-grey bill, legs and feet, and dark brown eye. Their wings appear short, their upper and lower surfaces brown and the speculum on the secondary feathers is green.

Male Pateke

Length: 48 cm

Weight: 650 – 900 grams

Males in breeding plumage have an indistinct green iridescence on the head, occasionally a narrow white neck ring, dark chestnut breast, and conspicuously barred light and dark brown flank feathers with a whitish patch at the tail base.

Voice: male calls are soft, usually described as trills or piping, given in alarm and in territorial defense.

Female Pateke

Length: 45 cm

Weight: 550 – 800 grams

Females and juveniles are a uniformly dull but dark mottled brown.

Voice: The female has a rasping growl and a high-pitched and rapid quack.

BREEDING / ECOLOGY

Brown teal are monogamous and generally fiercely territorial. Most nesting is in late winter (July-September) but broods have been encountered in most months except late autumn. Typically nests are buried in dry locations deep within bases of rush, grass or fern clumps. Large pale fawn eggs, each about 10-11% of the female’s body weight, are generally laid daily. The average clutch is 4 or 6 (range 2 – 13) and the incubation period extends for about 27 – 30 days. Both parents guard the ducklings during their 50-55 days until fledging after which time they are forcefully evicted from the territory; the brood is usually raised within the territory.

Social structure:
monogamous

Breeding season:
Wild – July to October
Captivity – All year round

Nest type:
generally ground-level hollow, but may nest in trees upto 4m above ground level.

Nest description:
Intertwined sedge or grass leaves with down-line surface, often wedged deep into base of sedge or grass clumps or in a fern.

Maximum number of successful broods:
Wild = 2
Captivity = 4

Clutch size (mean):
4

Clutch size (min):
2

Clutch size (max):
14

Mean egg dimensions (length):
60 mm

Mean egg dimensions (width):
43 mm

Egg colour:
Pale fawn

Egg laying dates:
Wild – July to October
Captivity – All year round

Interval between eggs in a clutch:
24 hours days

Incubation behaviour:
female only

Incubation length (mean):
28 days

Incubation length (min):
27 days

Incubation length (max):
30 days

Nestling type:
precocial

Nestling period (mean):
1 day

Age at fledging (mean):
55 days

Age at fledging (min):
50 days

Age at independence (mean):
55 days (at fedging)

Age at first breeding (min):
6 months

Maximum longevity:
21 years (captivity)
wild – unknown

Maximum dispersal:
45km

Distribution

Wild Brown teal populations reduced down to just two restricted populations in the North Island (Northland, Great Barrier Island) but have been have been expanding due to extensive predator control and new populations being formed via the National Captive Re-introductions program.

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The brown teal population got down to as low as just 700 birds estimated in the wild in the year 2000. Since then an intensive conservation program by the Department of Conservation – Pateke Recovery Group have increased the population back up around 2500 birds in the wild.

Reintroductions

With successfull releases of captive birds back into the wild from the Brown Teal captive breeding program, we now have sustainable populations established in Corromandel, Tawharnui, Cape Kidnappers, Tutukaka, Purerua (Kerikeri) and Arthur Valley (Milford Sound) still in progress.

Even with all this great work which has changed the population trend from a decline towards extinction to now steadily increasing and in the recovery phase, numbers are still fewer than 2000 – 2500 Brown Teal in the wild, making the species the rarest waterfowl on the New Zealand mainland. The Department of Conservation, the volunteer captive breeding facilities (20), community groups and sponsorship partners have all helped make this program the success it is today.

Threats and conservation

The brown teal are making a conservation comeback as a species, but is still very reliant on effective predator control to maintain and grow their numbers. Their vulnerability to and exposure to mammalian predators is the main reason for their decline, the main introduced predators are stoats, cats, ferrets, dogs etc.

Loss of wetlands and habitat has also played its part, but even the best pateke habitat without predator control will not sustain them. Whereas even marginal habitat with effective predator control has proven successful.

Recovery of teal populations on mainland sites requires permanent and assiduous predator control or predator exclusion.

Behaviour and ecology

Brown teal formerly exploited a wide range of habitats including wet forests, extensive and occluded swamps, slow-flowing streams, lakes and estuaries. Their present day habitat lies mostly in agricultural environments wherein the birds use stock ponds as breeding and feeding sites, and also margins of small streams/drains that retain overhanging marginal vegetation.

Brown teal populations generally comprise a single aggregated flock and numerous widely dispersed pairs. Some pairs may occupy exclusive territories year-round in water-rich locations whereas others vacate their territories seasonally and return to them when autumn rains replenish water levels. These territories contain abundant food and escape cover and suitable nesting and brood-rearing habitat. Pairs using streams as territorial sites will forage and nest well beyond the stream margins.

Flocks arise from mid-summer aggregations of recent fledglings and of early moulted adults whose winter ranges have dried out. Other seasonally displaced adults also join but will leave the flock following autumn rains. Non-breeding birds may remain as a flock through winter and spring.

Brown teal are generally crepuscular to nocturnal in habit in agricultural and forested environments but at coastal sites feeding and loafing activity may also be influenced by tides, the birds being more active at low tides.

Food

Brown teal diet is diverse. A study from Great Barrier Island recorded 78 taxa including terrestrial, freshwater and marine invertebrates, fungi, and terrestrial and freshwater vegetation. Terrestrial foods included seeds of sedges, clover leaves, cased caddisfly larvae, beetles, caterpillars, moths and earthworms. In inter-tidal areas teal dabbled in soft sediments to extract gastropods and bivalves, crustacean and polychaete worms. They also extract flesh from cockles and small mussels. On freshwater ponds, teal have been observed eating leaves of various wetland plants.