The Marquesas Ground-dove, Alopecoenas rubescens, is restricted to two small islets (Hatuta’a and Fatu Huku) in the Marquesas Islands, French Polynesia. It inhabits wooded areas and shrubby vegetation on these islands, with individuals on Hatuta’a favouring the plateau and only rarely being found in vegetation near the sea (Holyoak and Thibault 1984). These two islets are both cat-free, and it is highly suspected that predation by cats has led to its absence from other islands in the group. There is evidence to suggest that it at least has occurred on Nuku Hiva, as the type-specimen is reputed to have been collected there, and subfossils have been reported from three other islets too, suggesting that it once ranged throughout the entire island group (Steadman 1989).
Drought is another potential threat that could be having a great effect on this species. On Hatuta’a in particular there can be large fluctuations in population as a result of drought conditions (Thibault et al. 2013, P. Raust in litt. 2012) and so climate change could have a large impact on this species if it were to increase the frequency of droughts in the region. The population on Hatuta’a was estimated at c.200-250 individuals in 1975 and 1987, and estimates increased to c. 1,000 individuals in 2007, though potentially in part a result of more accurate surveying (Thibault et al. 2013, P. Raust in litt. 2007, A. Gouni in litt. 2007). Following this though was a drought, and by 2010 the total population was suspected to be <200 individuals, but by 2012 the species was ‘abundant’ (Thibault et al. 2013), thus showing how droughts can cause major fluctuations in this species. The population on Fatu Huku is likely smaller than that on Hatuta’a, with only 6 individuals observed on the island in 2011 (Butaud 2011), and in the 1990s and 2002 it was considered to be 10-100 individuals or similar (Seitre and Seitre 1991, A. Gouni in litt. 2007). Based on this information the population is tentatively assessed to be stable, as population changes may be a result of climate-induced fluctuations rather than part of an ongoing decline.
The species is currently listed as Vulnerable under criterion D2 both globally and regionally (UICN France 2015, BirdLife International 2017) on the basis that it is only found on two very small islands, where the threat of the introduction of predators such as cats could rapidly lead to it becoming CR or EX. However, when a species may undergo population fluctuations a lower population estimate should be used (IUCN Standards and Petitions Subcommittee 2016). Considering that the species, as a result of droughts, may fluctuate to below 250 mature individuals it may be prudent to place the population size estimate in the range of 50-249 mature individuals. Therefore, given that the population is currently, tentatively, assessed to be stable, it is proposed that this species be uplisted to Endangered under criterion D, though we request any information regarding potential over-riding long-term trends in the species, as if the species were to be shown to be declining it may qualify as Critically Endangered under criterion C2a(ii), as potentially >90% of the global population may be found on Hatuta’a (if the 6 individuals found in 2011 on Fatu Huku represent the total population on the island).
We welcome any further information and comments regarding this proposed uplisting.
BirdLife International. 2017. Species factsheet: Alopecoenas rubescens. Downloaded from http://www.birdlife.org on 24/03/2017.
Butaud, J. F. 2011. Oiseaux de Fatu Huku (Marquises). Te Manu (Bulletin de la Societe d’Ornithologie de Polynesie 75: 5-6.
Holyoak, D. T.; Thibault, J.-C. 1984. Contribution à l’étude des oiseaux de Polynésie orientale. Memoires du Museum National d’Histoire Naturelle – Serie A: Zoologie 127: 1-209.
IUCN Standards and Petitions Subcommittee. 2016. Guidelines for Using the IUCN Red List Categories and Criteria. Version 12. Prepared by the Standards and Petitions Subcommittee. Downloadable from http://www.iucnredlist.org/documents/RedListGuidelines.pdf.
Seitre, R.; Seitre, J. 1991. Causes de disparition des oiseaux terrestres de Polynésie Française. South Pacific Regional Environment Programme, Nouméa.
Steadman, D. W. 1989. Extinctions of birds in Eastern Polynesia: a review of the records and comparisons with other Pacific Island Groups. Journal of Archaeological Science 16: 177-205.
Thiabult, J.-C.; Cibois, A.; Butaud, J.-F.; Jacq, F. A.; Poroi, E.; Meyer, J.-Y. 2013. Breeding birds of Hatuta’a, Marquesas Islands: species inventory and influence of drought on their abundance. Bull. Brit. Orn. Club 133(3): 168-177.
UICN France; MNHN; SOP Manu. 2015. La Liste rouge des espèces menacées en France – Chapitre Oiseaux de Polynésie française. Paris, France.