Tongan Scrubfowl (Megapodius pritchardii): revise global status?

This discussion was first published as part of the 2018 Red List update. At the time a decision regarding its status was pended, but to enable potential reassessment of this species as part of the 2019 Red List update this post remains open and the date of posting has been updated.

Tongan Scrubfowl (Megapodius pritchardii) is endemic to Tonga and, although fossil evidence suggests it once had a wider distribution, it is now only found on two islands; a remnant population on Niuafo’ou, and a re-introduced population on Fonualei. A re-introduction has also taken place on Late, but there is no evidence of its persistence there (MEECCDMMIC 2014). The species is currently listed as Endangered under criteria B1ab(v)+2ab(v), on the basis that it has a very small range, with population size that is declining as a result of egg harvesting and hunting (BirdLife International 2018).

In 1979 the population size on Niuafo’ou was estimated at 820 adults (Todd 1983). Since 1993 the collecting of eggs of this species has declined (Lloyd 2011), but population declines on the island may have continued. In 1991-1993 the population size was estimated at 188-235 pairs (Göth and Vogel 1995), with surveys since suggesting a far smaller population. In 2010 only 10 active nests were found (Lloyd et al. 2011); in 2012, 33 burrows were located (MLECCNR 2012); and in 2014, 44 burrows and 28-53+ individuals were found (Butler 2014). The species does, however, appear to be doing well on Fonualei, with the population there estimated in 2004 to be 300-500 birds (Watling 2004), which had risen by 2013 to an estimate of 600-1,000, assuming that all apparently suitable habitat has been occupied (Butler 2013). Therefore, the population may be tentatively assumed to now be increasing overall despite the ongoing decline on Niuafo’ou (G. Dutson in litt. 2016). This would then mean that it no longer meets the conditions for listing as Endangered under criterion B. Therefore, the species has been re-assessed against all criteria based on current best information.

 

Criterion A – The population is currently considered to be increasing and does not approach the threshold for Vulnerable under this criterion.

 

Criterion B – Its EOO and AOO meet the threshold for Endangered under criteria B1 and B2 respectively. However, given that the population size of the species is now considered to be increasing, it does not meet the conditions for listing as threatened under criterion B any more.

 

Criterion C – Despite the species being estimated to have a very small population size, given that the population is now considered to be increasing overall, the species does not meet the threshold for Vulnerable under this criterion.

 

Criterion D – Given the estimates of population on each island, overall the global population may be considered to fall in the range 250-999 mature individuals. Additionally, the species is restricted to only 2 small islands where hunting and egg harvesting are the main threats. Therefore, it would warrant listing as Vulnerable under criteria D1 and D2.

 

Criterion E – To the best of our knowledge no quantitative assessment of the probability of extinction has been conducted for Tongan Scrubfowl, and so it cannot be assessed against this criterion.

 

Therefore, it is proposed that Tongan Scrubfowl be listed as Vulnerable under criteria D1+2. We welcome any comments on this proposed downlisting.

 

Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’ Red List status. Therefore, please make sure your comments are about the proposed listing.

 

References

BirdLife International. 2018. Species factsheet: Megapodius pritchardii. Downloaded from http://www.birdlife.org on 04/01/2018.

Butler, D. J. 2013. Bird surveys of Late and Fonualei Islands, Vava’u, Kingdom of Tonga, September 2013. Ministry of Lands, Environment, Climate Change and Natural Resources., Nuku’alofa, Tonga.

Butler, D. J. 2014. Field surveys and consultations to support the conservation of the endemic Malau, Polynesian Megapode. Ministry of Environment, Energy, Climate Change, Disaster Management, Meteorology, Information and Communications, Nuku’alofa, Tonga.

Göth, A.; Vogel, U. 1995. Status of the Polynesian Megapode Megapodius prithchardii on Niufo’ou (Tonga). Bird Conservation International 5: 117-129.

Lloyd, H. 2011. Polynesian megapode surveys on Niuafo’ou, Tonga. World Pheasant Association News: 10.

Lloyd, H., Torres-Sovero, C. and Faka’osi, S. 2011. Conservation Strategy for the Polynesian Megapode Megapodius pritchardii on Niuafo’ou, Tonga. World Pheasant Association, Newcastle, UK and Tonga Community Development Trust, Tongatapu, Tonga.

MEECCDMMIC. 2014. Threatened Species Recovery Plan Polynesian Megapode (Megapodius pritchardii) 2014-2024. MEECCDMMIC, Nuku’alofa, Tonga.

MLECCNR. 2012. Report on a visit to Niuafo’ou Island, Kingdom of Tonga. The Polynesian megapode (Megapodius pritchardii), monitoring and conservation of malau on Niuafo’ou Island. Ministry of Lands, Environment, Climate Change & Natural Resources, Nuku’alofa, Tonga.

Todd, D. 1983. Pritchard’s Megapode on Niuafo’ou Island, Kingdom of Tonga. World Pheasant Association Journal: 69-68.

Watling, D. 2004. No sign of translocated Polynesian Megapodes on Late Island, Kingdom of Tonga. Megapode Newsletter 18: 4.

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One Response to Tongan Scrubfowl (Megapodius pritchardii): revise global status?

  1. Hannah Wheatley (BirdLife) says:

    Preliminary proposal

    Based on available information, our proposal for the 2018 Red List would be to pend the decision on this species and keep this discussion open until 2019, while leaving the current Red List category unchanged in the 2018 update.

    Final 2018 Red List categories will be published on the BirdLife and IUCN websites in November, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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