Justification
Oeonia volucris, an epiphytic orchid endemic to Madagascar, is known from humid forests between sea level and 1,500 m elevation.
The species is recorded from 110 collections. Twelve (12) observations were also recorded but are without accurate coordinates, and thus not taken into account in this assessment. The 110 collections were made between 1881 (Lantz s.n.) and 2017 (Spirit Collection, Ambatovy 3056A5557), representing 57 occurrences among which 16 collections representing 15 occurrences were made in five protected areas. In addition to these legally protected sites, 62 collections representing 28 occurrences were made within the footprint of a mining project that has undergone and is undergoing intense human pressure from forest clearing, and these occurrences should now be considered as extirpated. Another occurrence (Ranaivojaona 828) at Ambahy, should likewise be considered as extirpated due to slash-and-burn agricultural practices (tavy). Two occurrences (Antilahimena 7005, and Bernard 1117) were collected in the Conservation Zone surrounding the mine footprint, this zone should be protected in the near future. The occurrences near Pointe à Larrée (Andrianarivelo 10, Rabenantoandro 1488) are threatened by the forest conversion to residential land, wood harvesting for subsistence, housing, and small-scale agriculture, these occurrences will probably be extirpated in the near future. Moreover, 20 collections representing 19 occurrences in unprotected sites are facing threats from forest clearing due to shifting agriculture, slash and burn agricultural practices (tavy), and forest degradation due to small-scale agriculture, along with wood harvesting for subsistence, contributing to a decline in habitat extent and quality of the species. The species is thus known from 102 collections with accurate coordinates representing 28 existing and 29 extirpated occurrences (28 within the footprint of a mining project, one at Ampasimaneva).
The extent of occurrence (EOO) of O. volucris is calculated as 70,118 km2 far exceeding the upper limit for vulnerable status under subcriterion B1, whereas its area of occupancy (AOO) is estimated at 108 km2 which is below the upper threshold of the Endangered status under subcriterion B2. These 27 existing occurrences represent a total of 26 locations (sensu IUCN 2022) with respect to the most serious plausible threat, forest clearing due to mining activities. The species is not severely fragmented and does not meet the threshold of any threatened categories under criterion B. Twenty-nine out of 58 occurrences of the species have disappeared, and two will be extirpated in the near future, these occurrences represent 13% of the AOO from 124 km2 in 2000 to 108 km2 in 2030 which cannot lead to consider the species under a threatened category according to criterion A. Due to the wide distribution and population size of the species, criteria C and D cannot be applied. Therefore, despite the projected continuing decline in the quality of its habitat, Oeonia volucris is assessed as Least Concern (LC).
Geographic Range Information
Oeonia volucris, is known from Madagascar where it is known from seven regions, the Sava Region (Natural Reserve n°2) from the formerly recognized Province of Antsiranana, the Alaotra-Mangoro Region (Ambatovy, Torotorofotsy), and the Analanjirofo Region (Lohan'ny Ambitsy forest, Antanambao, Ambohodena), the Atsinana Region (Andondabe, Ambila Lemaitso, Nankinana, and Tampina) from the formerly recognized Province of Toamasina, the Anosy Region (Mandena and Tsitongambarika), from the formerly recognized Province of Toliara, the Atsimo-Antsinanana Region (Agnalazaha), and the Vatovavy Region (Ambahy, Ampasimaneva, Mananjary, and Sakafotsy) from the formerly recognized Province of Fianarantsoa.
Population Information
The population of Oeonia volucris is currently thought to be decreasing since 28 occurrences on a mine footprint have been extirpated as well as one occurrence in an unprotected forest. The number of mature individuals cannot be estimated since the species is an epiphyte growing on lower branches of trees in humid forest.
Habitat and Ecology Information
The species is an epiphytic herb growing on branches of trees, up to 1.5 to 3 m above ground in littoral forests and evergreen humid forests, from sea level to 1,500 m elevation. (Hermans et al. 2007).
Threats Information
The species is threatened by forest clearing due to mining activities, forest degradation due to small scale agriculture and logging, and wood harvesting for subsistence, forest conversion to residential land.
Use and Trade Information
There are no reported uses of this species, but it may be sought after by specialist collectors.
Conservation Actions Information
The species is known from five protected areas: Analamazaotra National Park (Rakotondrafara 931), the Natural Ressources Reserve of Agnalazaha (Rabehevitra 463; Ludovic 654, 708, and 1467; Randrianasolo 854), the Protected Harmonious Landscape of Mandena (Jonsson 1095, and Rabevohitra 1895), the Protected Area of Torotorofotsy (Andriantiana 118; Antilahimena 6220, 6766; Ambatovy spirit collection 823Z4/1; 824Z4/2; Ambatovy ZC 4, and 7), the Natural Forest of Tsitongambarika (Razakamalala 3974). Individuals from this species have been brought to cultivation in the Ambatovy shade house. The species is also currently placed in Appendix II of CITES.
