Data Zone
Justification of Red List category
Following conservation efforts the population trend overall is now believed to be stable or increasing, and to have been so since the early 2000s. Due to this, the species no longer qualifies as Endangered, and would not have done so within the past five years. But the species still has a very small population and range restricted to two locations on two tiny islands. Both locations could be quickly destroyed by one or more of the known plausible threats of hunting, egg collecting, volcanic activity or incursions by invasive mammalian predators. Consequently, the species is listed as Vulnerable.
Population justification
In the most comprehensive and robust population study on Niuafo’ou, Göth and Vogel (1995) used playback to estimate the global population to be 188-235 pairs. More recent surveys have only been brief and used different methods but only located 28-53+ birds (Butler 2014). Göth and Vogel (1995) recorded 187+ active burrows, but only 33 were found in 2012 (MLECCNR 2012) and 44 in 2014 (Butler 2014). On Fonualei Island, Watling (2004) recorded a minimum of 38 individuals, and estimated a population of 300-500. In 2012, Butler (2013) observed that birds were also abundant at another site in the north of the island, and estimated a population of 600-1000, assuming that all apparently suitable habitat had been occupied. Watling (2004) and (Butler 2013) recorded no birds on Late. Thus the population size may be best placed in the range 250-999 mature individuals (G. Dutson in litt. 2016).
Trend justification
The overall population trend is tentatively considered to be increasing, as a result of estimated increases of the reintroduced population on Fonualei (Watling 2004, Butler 2013), despite the reported declines on Niuafo'ou (Goeth unpublished data, in Tilmouth 2010, Lloyd et al. 2011).
Megapodius pritchardii is endemic to Tonga where although fossil evidence indicates it was once widespread, there is now only a remnant population on the island of Niuafo'ou and a re-introduced population on Fonualei. On Niuafo'ou it is concentrated around the inner slopes of the caldera (a large sunken water- and forest-filled crater formed after volcanic activity) and on two cat-free islets in the crater lake.
In 1979, the population was estimated at 820 adults (Todd 1983) and, in 1991-1993, at 188-235 pairs occupying 641 ha of 719 ha of suitable habitat (Göth and Vogel 1995). This represents 52-65% of possible carrying capacity, assuming an average of 0.5 pairs per ha (Göth and Vogel 1995). Comparisons between individual sites and interviews with local people had strongly suggested an overall decline (Göth and Vogel 1995).
From 1991 to 1993, 60 eggs were buried at volcanically heated sites on Late (Göth and Vogel 1995), and an additional 35 eggs and chicks were transferred to Fonualei (Rinke 1994), both uninhabited and rarely visited by humans. A 2003 survey on Fonualei found the species to be common, comprising an estimated 300-500 adult individuals (Watling 2004), but there is no evidence of its continued existence on Late (MEECCDMMIC 2014, R. W. R. J. Dekker in litt. 2003, R. Dekker in litt. 2004). By 2013, the population on Fonualei had risen to an estimated 600-1,000 birds, assuming that all apparently suitable habitat was occupied (Butler 2013).
A survey in September 2010 revealed that the population on Niuafo'ou had undergone a dramatic decline in the number of nests at all known nesting grounds, and is now confined to small areas within the caldera. Historically, 27 nests were known from 13 different sites across Niuafo'ou (Goeth unpublished data, in Tilmouth 2010), but during the September 2010 survey only 10 active nests at 7 sites were found (Lloyd et al. 2011). The 2010 survey also failed to uncover any new nesting grounds since the research of Göth and Vogel (1995, 1997).
As a result of the population increase on Fonualei, the population may be tentatively assumed to now be increasing overall despite the ongoing decline on Niuafo’ou (G. Dutson in litt. 2016).
It inhabits broadleaved forest ranging from secondary to mature (Göth and Vogel 1995), but needs areas with little ground cover where it can forage in leaf-litter and top soil; mainly for insects and worms, but also small reptiles, seeds and small fruit (Rinke et al. 1993). It uses hot volcanic ash to incubate its eggs, a habit which confines its nesting sites to areas of loose soil close to vents, either in forest or in open ash, or beaches of crater lakes (Todd 1983).
A study in 1993 revealed that all nesting sites on Niuafo'ou were harvested with at least 50% of all eggs laid being collected or destroyed (Göth and Vogel 1995). However, egg collecting appears to have decline markedly since 1993 (Lloyd 2011) and younger people are reportedly not interested in maintaining this tradition (MEECCDMMIC 2014). The reason for the recent decline in the number of nest sites is currently unknown. One possibility is that natural shifts in geothermal activity may have caused changes in soil temperature profiles that would inhibit successful incubation of eggs (Tilmouth 2010). Adults are also hunted on a small scale, and both adults and chicks are predated by feral cats and dogs, while pigs almost certainly destroy suitable foraging habitat for young birds (Lloyd 2011) and may compete for food (Göth and Vogel 1995). Fonualei is uninhabited so the threats of hunting and human disturbance are less immediate for the reintroduced population there (R. Dekker in litt. 2004).
Conservation Actions Underway
It is legally protected, although in practice there is no enforcement. From 1991 to 1993, 60 eggs were buried at volcanically heated sites on Late (Göth and Vogel 1995), and an additional 35 eggs and chicks were transferred to Fonualei (Rinke 1994), both uninhabited and rarely visited by humans. Breeding was successful on Fonualei and the population appears to be established (R. W. R. J. Dekker in litt. 2003, C. Matevalea verbally 1999, Watling 2004), but surveys suggest the translocation failed on Late (R. Dekker in litt. 2004, A. Göth in litt. 2004). A Conservation Strategy for the species was published in 2011 by the World Pheasant Association and the Tonga Community Development Trust (Lloyd et al. 2011), and an Action Plan produced in 2014 (MEECCDDMMIC 2014).
38 cm. Medium-sized, brown-and-grey megapode. Mostly brownish-grey, paler on head and neck, browner on back and wings, with short, rounded crest on nape. Feathers of face and throat sparse, allowing red skin to show through. Yellow bill. Yellow to light red legs and feet. Similar spp. Buff-banded Rail Gallirallus philippensis has bold bars and much longer bill. Immature Purple Swamphen Porphyrio porphyrio larger with white undertail-coverts. Feral chickens have prominent tails. Spotless Crake Porzana tabuensis smaller and darker with red eyes and legs. Voice Three-part whistle kway-kwee-krrrr from male, usually uttered in duet with female krrrr. Both male and female can initiate the duet.
Text account compilers
Westrip, J., Dutson, G., Elliott, N., Wheatley, H., Mahood, S., Keane, A., O'Brien, A., Stattersfield, A., Derhé, M.
Contributors
Dekker, R., Dutson, G., Fakaosi, D., Göth, A., Matevalea, C. & Watling, D.
Recommended citation
BirdLife International (2024) Species factsheet: Tongan Scrubfowl Megapodius pritchardii. Downloaded from
https://datazone.birdlife.org/species/factsheet/tongan-scrubfowl-megapodius-pritchardii on 26/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 26/12/2024.