- Tasmanian Nativehen
 - Tasmanian Nativehen
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Tasmanian Nativehen Tribonyx mortierii Scientific name definitions

Barry Taylor
Version: 1.0 — Published March 4, 2020
Text last updated November 25, 2013

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Editor's Note: This is a shorter format account, originally published in HBW Alive. Please consider contributing your expertise to update and expand this account.

Identification

42–51 cm; male (mean) 1334 g, female (mean) 1251 g. Large , thickset, flightless rail, rather bantam-like, with long, narrow tail, and stout bill and legs ; conspicuous, active, noisy, demonstrative and aggressive; walks with short wings partly drooped and tail constantly jerked up and down or carried erect; runs very swiftly with tail erect, opening wings to balance. <em>T. ventralis</em> much smaller and longer-winged, with dark area round base of bill, white spots on sides of belly sometimes covering rear flanks, no pale tips to upperwing-coverts, orange-yellow iris, pale green bill with red base to lower mandible, and pinkish red legs and feet. Sexes alike. Immature like adult except for narrower juvenile remiges. Juvenile  duller and paler overall; as plumage becomes worn, white patch develops on lores and buff tips show from back to uppertail-coverts; feathers of breast and belly have whitish tips; bare parts as in adult, but bill initially dusky.

Systematics History

Monotypic.

Subspecies

Introduced to Maria I (off E Tasmania).

Distribution

Tasmania.

Habitat

Open pasture, grassland , crops (newly sown cereals or legumes) and other cleared land round permanent or seasonal freshwater wetlands which include marshes, lakes, dams, creeks, rivers and streams; rarely round saline wetlands. Grassland may be lightly timbered or infested with alien weeds; usually frequents wetland areas with abundant cover of rushes, reeds, sedges, tussocks, bracken or willows for shelter and nesting. Occasionally enters adjacent woodland, or penetrates forest along tracks and in clearings. Occurs throughout agricultural areas, especially where farming less intense; absent from heath dominated by button-grass in SW. Requires short-grazed pasture all year for foraging; currently dependent on swards maintained by introduced species (rabbits, sheep and cattle); swards formerly maintained by grazing marsupials and by fire. Always breeds near water  .

Movement

Sedentary, but some groups recorded as disappearing in summer. Many young disperse from natal area at end of first year, but on Maria I 20–30% of young were still in natal territories at end of 2nd year. Movements of up to 15 km recorded; once 40 km.

Diet and Foraging

Mostly seeds and leaves of: Poaceae, Cyperaceae, Restionaceae, Juncaceae, Polygonaceae, Portulaceae, Caryophyllaceae, Brassicaceae, Rosaceae, Fabaceae, Geraniaceae, Thymelaceae, Apiaceae, Epacridaceae, Primulaceae, Convolvulaceae, Boraginaceae, Scrophulariaceae, Plantaginaceae, Rubiaceae, Asteraceae and Hydrocharitaceae; also cereal crops; diet varies with availability of plant species. Also takes a few insects (Orthoptera, Coleoptera, Diptera and Lepidoptera); in captivity eats meat and fish. Herbage eaten most in winter and spring, seeds and insects in summer. Young chicks given worms , insects and tadpoles as well as plant material; by 14 days of age, diet as adult. Diurnal; forages on ground in pastures and paddocks; also on exposed mud. Gleans and pecks at ground and seedheads ; grasps herbage and pulls seeds off with tip of bill; in orchards takes fruit from ground or low branches, sometimes hopping onto branches; chases flying moths. A secondary grazer, requiring primary grazers to maintain suitable habitat.

Sounds and Vocal Behavior

Characteristic aggressive call of pairs is loud, rasping, antiphonal “see-saw”. Also various grunts, a repeated click call, sharp and harsh alarm calls, and screaming calls when chased or attacked. Noisy early in morning and in evening; also calls at night.

Breeding

Jul–Jan, usually Aug–Nov; determined by rainfall, as dependent on fresh young plant growth. Monogamous or polygamous, usually polyandrous; permanently territorial in groups of 2–17 birds consisting of 2–5 breeding adults, plus young usually up to 2 years old. Breeding unit usually adult pair, or trio of 2 males (often brothers) and 1 female; rarely has 2 females (sisters). Adults normally associate for life. All males perform copulations. Sex-ratio biased towards males. Adults share all territorial and breeding duties; young of previous year sometimes help with breeding duties; first-brood young sometimes feed and brood second-brood chicks. Nest a bulky woven cup of grass, reeds or herbage, well concealed in tall, thick vegetation such as rushes, reeds, sedges, tussocks, ferns, prickly bushes, occasionally thistles. Built 10–120 cm above ground or over water, almost always on edge of stream, dam, lagoon or pond; sometimes under overhang or in hole in creek bank; concealed overhead with woven stems; entrance leads towards water. Also constructs 1–7 brood nests after eggs hatch; usually in exposed location and often untidier and bulkier than egg-nests. Usually 5–8 eggs (3–9), laid at daily intervals; incubation 19–25 days (usually 22); eggs normally hatch within 48 hours; downy chick black (fading to dark brown), bill black with large white egg-tooth, pink base to upper mandible, and narrow lavender saddle, iris black, legs and feet grey-black; chicks semi-precocial and nidifugous; leave nest 1–2 days after hatching; become self-feeding  after 1–2 weeks but fed for 8 weeks; tended closely for 3–4 weeks and then less frequently until 6 weeks old; usually remain with parents until 9–15 months; post-juvenile moult occurs before first winter. Able to breed in first year. Hatching success 89%; survival of young  to 4 months 46% in adult pairs and 61% in trios; survival higher in adult groups than first-year groups. Often rears 2 broods per season, sometimes 3.

Not globally threatened (Least Concern). Distribution has not changed substantially in recent past, although has expanded into newly opened land. Introduced to Maria I in 1969. Has benefited from introduction of rabbits as well as clearance of wooded land for grazing and crops, and construction of artificial wetlands. Road construction may provide corridors for range expansion. Very nume­rous, despite some local declines. Drastic decline near Geeveston, S Tasmania, in 1989, thought to be result of disease. Decline reported in Midlands after introduction of myxomatosis and consequent reduction of rabbits; recent spread of rabbit calicivirus on Australian mainland, if extending to Tasmania, could have similar effect. Not protected: traditionally regarded as agricultural pest: claimed to trample, graze and foul pasture and crops; most claims unsubstantiated, but species may reduce sprouting oats by up to 8%. Declared vermin in 1950, and thousands were killed in 1955–1958; still controlled by shooting and round-ups. Attacked by feral cats and dogs. Killed by road traffic; appears particularly susceptible on elevated sections of roads. Formerly occurred on mainland Australia (SE Queensland to Victoria and SE South Australia); thought to have become extinct 20,000–12,000 years ago during a period of severe aridity; however recent finding of remains only 4700 years old suggests that final disappearance coincided roughly with arrival of dingo (Canis familiaris dingo). In Tasmania survives predation by cats as well as native species such as Tasmanian devil (Sarcophilus harrisi).

Distribution of the Tasmanian Nativehen
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  • Year-round
  • Migration
  • Breeding
  • Non-Breeding
Distribution of the Tasmanian Nativehen

Recommended Citation

Taylor, B. (2020). Tasmanian Nativehen (Tribonyx mortierii), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.tanhen1.01