Iphis Monarch, Pomarea iphis, is restricted to the island of Ua Huka in the Marquesas Islands, French Polynesia. The species appears to prefer forested habitat, with breeding individuals found in native low- to mid-elevation moist/wet forest and locally in dry forest (Thibault and Meyer 2001). The number of breeding pairs was originally estimated at several hundred in 1975 (Holyoak and Thibault 1984), and more recently at 500-1,250 pairs (Thibault and Meyer 2001).
Being restricted to the same single island as the Ultramarine Lorikeet, Vini ultramarina, some of the same threats are likely to affect this species. Its habitat may be under threat as grazing (by feral goats and cattle) and fire have led to the loss of dry forest (WWF/IUCN 1994-1995), while sections of habitat have also been cleared for agriculture, as well as to make wood carvings for tourism (Doukas et al. in litt. 2010). While no directly estimated population decline has been recorded for the species, this loss of habitat is likely to be causing a slow, on-going decline in the extent and quality of the species’s habitat. Additionally the Black Rat Rattus rattus, although not yet present on the island, has been the likely cause of several extinctions in the region, while introduced birds (which may transmit diseases), the yellow crazy ant and Singapore ant, plus feral cats are all present on Ua Huka (C. Blanvillain in litt. 2016).
Iphis Monarch is currently listed as Vulnerable under criterion D2, on the basis that it is confined to one island with plausible threats that could drive the species to CR or EX in a short period of time (see BirdLife International 2017). However, the recent French Regional Red List assessment (UICN France 2015), which included an assessment of the birds of French Polynesia, listed this species as Endangered under criterion B1ab(iii), and following a review of BirdLife’s Extent of Occurrence (EOO) data it has been noticed that this species would actually meet the threshold for Critically Endangered under criterion B1.
The EOO that is currently used for assessing this species is 100km2, but this arose from the EOO value being rounded up from 99km2. The threshold value to be considered for potential listing as Critically Endangered under criterion B1 is <100km2, therefore by rounding this value it moved the EOO over this threshold value, and the original EOO of 99km2 should be used. However, this is not the sole condition for a species to be listed as CR under criterion B1. Two of the following three conditions must also be met to qualify as Critically Endangered: a) the species must be found at only one location* or its range must be severely fragmented; b) the species must be undergoing a continuous decline in (i) extent of occurrence; (ii) area of occupancy; (iii) area, extent and/or quality of habitat; (iv) number of locations or subpopulations; (v) number of mature individuals; and c) it experiences extreme fluctuations in (i) extent of occurrence; (ii) area of occupancy; (iii) number of locations or subpopulations; (iv) number of mature individuals. The species is not known to undergo extreme fluctuations so condition c) can be discarded, but being found on only one very small island the species does meet condition a). The species is currently thought to be stable, but given that at least the area and quality of habitat is likely declining, the species would meet condition b(iii). Therefore, it is proposed that this species be listed as Critically Endangered under criterion B1ab(iii).
We welcome any comments regarding this proposed uplisting.
*Note that the term ‘location’ defines a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the taxon present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat (IUCN 2001, 2012).
BirdLife International. 2017. Species factsheet: Pomarea iphis. Downloaded from http://www.birdlife.org on 03/04/2017.
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. 2001. IUCN Red List Categories and Criteria: Version 3.1. Gland, Switzerland and Cambridge, UK: IUCN Species Survival Commission.
IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN.
Thibault, J.-C.; Meyer, J.-Y. 2001. Contemporary extinction and population declines of the monarchs (Pomarea spp.) in French Polynesia, South Pacific. Oryx 35: 73-80.
UICN France; MNHN; SOP Manu. 2015. La Liste rouge des espèces menacées en France – Chapitre Oiseaux de Polynésie française. Paris, France.
WWF/IUCN. 1994-1995. Centres of plant diversity: a guide and strategy for their conservation. International Union for Conservation of Nature and Natural Resources, Cambridge, U.K.