Data Zone
Justification of Red List category
This species has a small population within a very small range: almost certainly only now occurring on one very small island. Although it may currently be increasing there owing to a cessation of mining activities and hunting, it could decline rapidly in the near future owing to habitat destruction, or if Swamp Harrier Circus approximans colonises the island. Recent surveys suggest that the population size is larger than previously thought, but the imminent threat of a resumption of mining activities on Makatea means that future continuing declines in area of occupancy, area/quality of habitat and population size are likely. Therefore, the species is listed as Endangered, though if these future threats do not materialise the species will warrant downlisting.
Population justification
A survey on Makatea in 2009 (Albar et al. 2009, 2010) estimated the total population size at 1,206 individuals (with a 95% confidence interval of 867-1,677 individuals; roughly equivalent to 570-1,200 mature individuals), and the population size is assumed to be stable or slightly increasing.
Trend justification
Population estimates are too inaccurate to detect trends, although hunting has been much reduced and the species may be increasing on Makatea where forest is regenerating. An overall increase of 1-9% is suspected to have taken place over the last ten years. However, a future decline is very possible given the plans for infrastructure development and the distinct possibility that C. approximans could colonise the island.
Ducula aurorae is known from Tahiti in the Society Islands and Makatea in the Tuamotu Archipelago, French Polynesia. On Tahiti, it may already be extinct, it was restricted to the Papeno`o and Hitia`a valleys in 1986-1990 (Monnet et al. 1993), but none were reported in 1998 and in 2006 it was considered unlikely to persist (Thibault and Cibois 2006). On Makatea, the population was judged to lie between 100 and 500 individuals in 1986-1987, but have since increased following a reduction in hunting (Thibault and Guyot 1987, Thibault and Cibois 2006). A survey on Makatea in 2009 estimated the total population size at 1,206 individuals (95% C. I., 867-1,677) (Albar et al. 2009, 2010). This appears to be a genuine population increase, perhaps related to the cessation of mining activities and reduction of the human population on Makatea. There are also fossil records indicating that it was once more widespread, including in the Southern Cook Islands (Steadman 1989).
Though the species was formerly found only in dense forest, where it feeds on fruit from a variety of native and introduced trees, it has recently spread into secondary habitats and even gardens (Holyoak and Thibault 1984, Pratt et al. 1987, Thibault and Guyot 1987, Thibault and Cibois 2006). It is now an important seed disperser on Makatea, accelerating the spread of native forest into areas which had been mined (Thibault and Cibois 2006).
On Makatea, much of its habitat was destroyed during the period 1917-1964 as a result of phosphate mining, however it is now spreading as vegetation recovers and hunting is reduced (Thibault and Guyot 1987, P. Raust in litt. 1999, Thibault and Cibois 2006, Albar et al. 2009, 2010). However, Makatea is being considered for new mining activities, which may further affect the birds (Albar et al. 2010), and there is a high chance mining could restart in the near future (C. Blanvillain, T. Ghestemme and P. Raust in litt. 2017). A proposed runway and associated road and infrastructure development is likely to lead to renewed deforestation (Thibault and Cibois 2006). Predation by introduced cats and rats (particularly black rat Rattus rattus) may be a problem (Monnet et al. 1993), although the species has coexisted with rats for several decades (J.-C. Thibault in litt. 2000). On Moorea, Tahiti and other formerly inhabited islands, its extinction may have been the consequence of the spread through the Society Islands of the Swamp Harrier Circus approximans (Holyoak and Thibault 1984, Thibault 1988, Seitre and Seitre 1991, Thibault and Cibois 2006). This species continues to spread throughout the region, and its arrival on Makatea would be disastrous for D. aurorae (Thibault and Cibois 2006).
Conservation Actions Underway
On Tahiti, a year-long study in 1998 collected information from the inhabitants of the valleys where it was last recorded (J.-C. Thibault in litt. 2000). Work was carried out in 2009 by Société d’Ornithologie de Polynésie Manu to determine the population size of the species through distance sampling (Albar et al. 2009, 2010).
51 cm. Large, knob-billed pigeon with broad rounded wings. Silver-grey head and most of underparts, dark bronzy-green upperparts, black undertail-coverts. Similar spp. Feral pigeon Columba livia much smaller and does not live in forests. Voice Gruff, hoarse rouw-rouw-rouw and variety of quieter notes.
Text account compilers
Mahood, S., Dutson, G., Stattersfield, A., Westrip, J., Derhé, M., Wheatley, H., Symes, A., Shutes, S., O'Brien, A.
Contributors
Thibault, J., Kesler, D., Ghestemme, T., Blanvillain, C., Raust, P.
Recommended citation
BirdLife International (2024) Species factsheet: Polynesian Imperial-pigeon Ducula aurorae. Downloaded from
https://datazone.birdlife.org/species/factsheet/polynesian-imperial-pigeon-ducula-aurorae on 23/11/2024.
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 23/11/2024.