North Island Takahe Porphyrio mantelli Scientific name definitions

63 cm; stands c. 50 cm tall; male 2250–3250 (2673) g, female 1850–2600 (2268) g. Largest living rallid; thickset, flightless species with reduced wings, massive bill and powerful legs and feet; plumage loose and has silken sheen. Female is slightly smaller than male. Unmistakable: much larger and more robust than <em>Porphyrio porphyrio</em> . Immature is like adult but slightly duller; bill pinkish with bluish cast; legs and feet dull red or pale brownish-orange; iris attains adult colour by 5–6 months. Juvenile is predominantly brownish-grey on head, neck and upperparts; face and throat mottled white; upperparts attain brownish tinge with wear; breast and upper flanks dull purplish-blue; rear flanks to vent cream-buff; undertail-coverts white; wing feathers grow last and resemble those of adult; iris dark brown to grey; bill and developing frontal shield almost black, later fading to light brown or pinkish; legs and feet horn to dark purplish-brown. Races differ in skeletal measurements, <em>hochstetteri</em> having shorter leg bones (nominate race known only from subfossils).

Estimated year of extinction 1894. Demise attributed to anthropogenic modifications of habitat combined with hunting and predation.

North I, New Zealand. Known from subfossils from a number of archaeological sites (3 Williams, G.R. (1960). The Takahe (Notornis mantelli Owen, 1848): a general survey. Trans. Roy. Soc. New Zealand 88(2): 235–258. Close ) and one historical record in 1894 (4 Phillipps, W.J. (1959). The last (?) occurrence of Notornis in the North Island. Notornis 8(4): 93–94. Close ).

Alpine tussock grassland; also subalpine scrub and beech (Nothofagus) forest in winter, when snow covers grassland; before population decline may also have inhabited coastal sand ridges and open shrubland. Alpine grassland dominated by snow tussock grass (Chionochloa) c. 1 m high, with sedges (Carex, Schoenus), short grass (Festuca, Poa), herbs and shrubs. Forest dominated by beech, with understorey of shrubs, ferns and grass. In Fiordland National Park occurs in area of heavy snows and very high rainfall (2500–4800 mm per annum), commonly above tree-line at 1050–1520 m. Where introduced on islands, occurs in pastures of exotic grasses (Bromus, Holcus, Dactylis) and clovers (Trifolium). Frequents mountain lakes, rivers, streams and bogs; often by fast-flowing streams; some areas prone to flooding.

Eats predominantly leaf bases of Chionochloa tussocks and other alpine grass species; leaf bases of Cyperaceae, grass seeds and fern (Hypolepis) rhizomes taken seasonally, mainly in winter; rarely takes invertebrates and small reptiles. On islands eats leaf blades, leaf bases and seeds of many introduced grasses, also leaves and bases of clovers, all parts of chickweed (Stellaria media), and occasionally dead sticks, grass and flax stalks. Pulls tussock tillers out with bill, transferring them to foot to hold them parrot-fashion; strips seeds from seedheads by running partly open bill along stalk, sometimes first biting off stem and holding it in foot; digs up fern rhizomes with bill. Feeds selectively, taking plant bases richest in nitrogen, phosphorus, calcium, sodium, potassium and soluble sugars. Active throughout day; in winter to 22:00 hours. Energy requirement c. 2·0–2·2 kcal/g/day.

Contact call a single rising squawk, “klowp”. Alarm call a low, resonant “boomp” or percussive “oomp”, repeated slowly. Also various clucking calls when feeding, and a loud screech or hiss when threatened, chased or caught. Contact call easily confused with that of Gallirallus australis, but generally deeper and more resonant.

Mainly Oct–Dec; eggs occasionally to mid-Feb and small young late Mar (probably from renesting after failure). Monogamous; pair-bond permanent, at least for 12 years and probably for life. Territorial  within loose colonies; territory maintained while breeding, thereafter pairs remain in semi-communal and overlapping home ranges; holds same territory each year; territory size 2–60 ha. Breeds in family groups; juveniles sometimes ejected, but first-year birds may assist with incubation and care of young; multiple male helpers reported in captivity. Nest built on well-drained ground among tussocks; typically has two entrances connecting with runways; has latrine nearby. Nest, built by both sexes, a deep bowl of fine grass and tussock leaves, placed in saucer-like scrape in ground. Trial and/or brood nests often also built. Clutch usually 2 eggs (1–3), with laying interval 48–72 hours; incubation period 29–31 days, by both parents; hatching asynchronous; chicks precocial and nidifugous; usually leave nest soon after hatching; black downy chick has black-brown iris, bill white with black base and frontal shield, legs and feet pale pink, becoming purple-brown; down fades to black-brown (pale brown to whitish from face to breast) and replaced by grey second down at 4–5 weeks; body feathers develop at 5–8 weeks, tail at 14–18 weeks, wings at 9–20 weeks; young fed and brooded by both parents; dependent on adults for food for c. 4 months; post-juvenile moult occurs at c. 4 months; develop adult calls at c. 4·5 months; usually remain with parents for winter and disperse in following spring, some remaining for up to two years. Fostering recorded in captivity. Age of first breeding 2 years; sometimes 1 year. Egg fertility 70–80%; hatching success 67–76%; survival to 1 year 27–71%, dependent on weather and locality; usually only 1 young raised to independence; adult survival 73–88% per year. Second brood recorded only once.

EXTINCT. Long extinct. Known only from subfossils. Formerly widespread on North I. Habitat reduced by spread of forest in post-glacial Pleistocene–Holocene, leaving birds more vulnerable to hunting by Polynesian colonists, who arrived c. 1000 years ago. Probably once widespread in both forest and grassland down to sea-level.