The New Caledonian Lorikeet Charmosyna diadema is a possibly extinct lorikeet endemic to the Melanesian island of New Caledonia.
It is 18-19 cm long (the size of a large hand), of which 7-8 cm are made up by the slim and pointed tail. The wings are likewise slender and pointed, measuring 91 mm in the only specimen; its tarsus is 16 long.
Female birds are green overall, with deep violet blue crown and dark bluish thighs, a yellowish face and underside face, and a red anal region. Tail green above, below yellowish olive; the four lateral feathers with red basal markings followed by a black band, tipped yellow on the underside. The beak is orange-red, the iris probably dark orange, as are the feet.
The males were never recorded. They can be expected to have more red coloration, probably including the face, the underside of the primaries and the rump sides, and be slightly larger. Immature birds should look like dull females.
The noises it makes are unknown but are believed to be high-pitched screeches. These would be the most telling sign of the species, but only to observers familiar with the other local parrots' vocalizations. While the birds would be unmistakable due to their small size, they are extremely hard to spot.
The provenance of the extant specimen is unknown. One was shot at Mont Ignambi near Oubatche in 1913 (Sarasin & Roux, 1913), but not preserved. Unverified reports exist from west of Mont Panié and the Mont Ignambi area in the North Province, and from the La Foa-Canala road and Yaté Lake in the South Province (Stokes, 1980; Forshaw & Cooper 1989; Ekstrom et al., 2002). Bregulla (1993) suggested it might be found in the area around Mont Panié and Mont Humboldt - about 60km SE of Canala - and the Massif du Kouakoué. Given the low accessibility of the highlands, flocks could in theory occur in any of the larger patches of comparatively undisturbed forest which remain, e.g. between the intercoastal roads around the province border.
This bird is hard to track because it is nomadic and is relatively inconspicuous. This species is believed to live in humid montane forests but (seasonally?) flies in and out of lowland Melaleuca forests. Most reports come from such lowland forests, but this probably reflects better accessibility. Mt. Ignambi is believed to be an ideal habitat for the species. The Yaté Lake report was from an area of low shrubland.
Apparently keeps to the treetops. Food of relatives consists of nectar, pollen, blossoms and in some species soft fruit; they are found foraging in pairs or small (typically less than 10 birds) flocks Erythrina was specifically mentioned as food plants of this species. Reproduction data of 'green' Charmosyna lorikeets is only available for the Red-flanked (C. placentis) and the Red-fronted Lorikeet (C. rubronotata). Breeding season probably is July-December, and possibly to February, or even all-year round. Nests are excavated in arboreal termite nests or epiphytic ferns. Clutches consist of two (sometimes three?) white rounded eggs; extrapolating from what scant data is available from relatives, those of C. diadema can be expected to measure about 19.6 x 18.7 mm.
Described from two skins (both females) collected somewhere on New Caledonia before 1860 (Berlioz 1945). One has since disappeared, the other is in the MNHN (specimen 762A). Sarasin & Roux (1913) report that the species was claimed to exist near Oubatche; one bird was shot but could not be preserved. Layard & Layard (1882), while not being able to observe birds themselves, report that it was reputedly seen until 1880, though being extremely rare. Forshaw & Cooper (1989) cite Anthony Stokes, who in December 1976 collected reports on sightings: An older local identified it from a colored plate and claimed to have observed a single bird in shrubland near Lake Yaté 'many years ago', possibly in the 1920s. A forestry official claims to have twice seen two individuals fly overhead, once in 1953 or probably 1954 on the La Foa-Canala road, and once on June 3, 1976 W of Mt Panié. However, none of these claims could be confirmed and all searches (e.g. 1938 by MacMillan) have been fruitless. Stokes also reported that rewards for live or dead specimens were offered by collectors coming to New Caledonia in search for this bird.
Opinion on whether the New Caledonian Lorikeet is still extant is divided; King (1981) lists it as extinct since 1860, which is certainly not correct. Most authors still hope it is yet to be found again; a hope that is not unsubstantiated given the fact that conditions for ornithological field work on New Caledonia are far from ideal and that C. diadema is a rather small, inconspicuous bird - and, obviously, in the light of the rediscovery of Aegotheles savesi in 1999, after being known only from a single male skin for 119 years. A 6-month search expedition to the Mt. Ignambi area in 1998 did not find the species, and locals were not familiar with it. New surveys of highland rainforests are planned for 2006/2007 .
Reasons for the species' rarity are unknown. There seems to have been a marked decline in the numbers of two of the other three parrots native to New Caledonia (the New Caledonian Red-crowned Parakeet and the Horned Parakeet; Deplanche's Lorikeet is still common) for which the reason is not readily discernible. The theory that the three rare parrot populations are/were rather susceptible to anthropogenic disturbance and habitat destruction is supported by the fact that a large number of New Caledonian birds seem ill-adapted to the consequences of interference by modern Homo sapiens, declining or disappearing wherever habitat is modified. C. diadema's post-1880 decline - if it was real - seems to have taken place far too early for habitat destruction being a decisive factor; neither could capture for the cage bird trade have had any significant influence. Introduced cats or rats could have been responsible for a decline in numbers, at least in theory, as could have been an introduced disease or any or both of these factors together with subtle habitat changes. For example, the large-scale destruction of lowland forest may have deprived the species of a food source they seasonally depended on. The introduction of cats and European rats in the mid-19th century fits the assumed pattern of decline; however, cats have probably not spread over the whole of the island until recent times. Rats, especially black rats which are arboreal probably represent a serious threat, but the species did not succumb to the prehistoric arrival of the Polynesian rat.
The only thing that can be said with some certainty about the New Caledonian Lorikeet is that all reports give the impression of an extremely rare and elusive bird. Actually, however, it could prove to be just extremely elusive, as its relative, the Red-throated Lorikeet, which was feared extinct since the beginning of the 20th century but apparently survived in considerable numbers to the 1970s, but it is more probable that C. diadema is genuinely rare. If any remain, it is most probable that the overall population is very small and, as indicated by the distance between sighting locations and remaining prime habitat, fragmented.
The New Caledonian Lorikeet is, like most parrots, listed in CITES Appendix II (since June 6, 1981) and European Union regulation 338/97 Appendix B (since June 1, 1997). It is listed as Critically Endangered (D1) by BirdLife International, which means that the effective population size is likely to be less than fifty individuals.