Justification of Red List Category
This species has not been recorded with certainty since 1913, despite specific searches in 1998 and between 2002 and 2011, and it may have declined as a result of a number of putative threats. However, it cannot be assumed to have gone Extinct, because there were local reports in the 1950s and in 1976, and lorikeets in this genus are notoriously difficult to detect, being unobtrusive and nomadic, so further surveys are required. Any remaining population is likely to be tiny, and for these reasons it is treated as Critically Endangered.
Any remaining population is assumed to be tiny (numbering fewer than 50 individuals and mature individuals), with no reports since 1976, despite recent searches in 1998.
Charmosyna diadema is known from two specimens collected in 1859, and another collected, but not preserved, in 1913 on New Caledonia (to France) (Sarasin 1913, Forshaw 1989). The first specimens are from an unknown locality and the 1913 record from the forests behind Oubatche which corresponds to Mt Ignambi. There are unconfirmed reports from the 1880s to the 1920s (Layard and Layard 1882, Stokes 1980), and an experienced forester reported two birds in 1953 or 1954 in the central mountains and again in 1976, west of Mt Panié (Stokes 1980). However, in 1998 there were no records during several months of specific searching, including on Mt Ignambi (Ekstrom et al. 2000, 2002).
The earliest reports were that it inhabited forest and occasionally fed in Erythrina trees (Layard and Layard 1882). The 1953-1954 and 1976 reports were from Melaleuca savanna/humid forest ecotone, while the 1920s report was from low scrubland (Stokes 1980, Forshaw 1989). Most closely-related species are nomadic and occur primarily in montane forest, but range into lowland forests, for which they may have a seasonal dependence (Forshaw 1989).
Montane humid forest is not under threat, but it is possible that this species has a requirement for other habitats, some of which, notably lowland semi-deciduous forests, have nearly disappeared from the island (Ekstrom et al. 2000, 2002). Several Charmosyna lorikeets have undergone severe population declines or fluctuations of unknown cause (Forshaw 1989). It is possible that introduced disease (such as avian malaria) or more likely mammals (notably rats) may have been a cause of decline (Bregulla 1992, Ekstrom et al. 2000, 2002).
Conservation Actions Underway
CITES Appendix II. The Mt Panié massif, one of the most likely sites where it may still occur, is a floral reserve where the habitat is protected but hunting is permitted (Jaffré et al. 1998). Two recent conservation reviews have recommended that this reserve is upgraded to a special faunal and floral reserve and also extended to include Mts Colnett and Ignambi to the north as one contiguous forest block (Maruia/CI 1998, Ekstrom et al. 2000). No new records were obtained during 500 man-days of bird censuses between 2002 and 2007 (J. Theuerkauf, S. Rouys and V. Chartendrault in litt. 2007). A total of 120 locals interviewed between 2003 and 2006 did not provide any credible reports (J. Theuerkauf, S. Rouys and V. Chartendrault in litt. 2007). The search was carried on until 2011.
19 cm. Bright green lorikeet. Green patterned with deep blue on crown and thighs, yellow face, red vent, red-and-black at base of yellow-tipped tail. Similar spp. Rainbow Lorikeet Trichoglossus haematodus is much larger and has dark blue head and red breast. Voice Unknown but probably very high-pitched screech as congeners, louder than that of Red-faced Parrotfinch Erythrura psittacea. Hints Check flowering trees in montane forest or possibly lowland semi-deciduous forest. Congeners often fly low over forest ridges, at dawn and dusk, calling repeatedly.
Text account compilers
Ekstrom, J., Dutson, G., Hermes, C., Stattersfield, A., Symes, A., Derhé, M.
Gilardi, J., Spaggiari, J., Rouys, S., Theuerkauf, J., Chartendrault, V.
BirdLife International (2019) Species factsheet: Charmosyna diadema. Downloaded from http://www.birdlife.org on 17/02/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 17/02/2019.