IUCN Red List Conservation Status: Endangered
The Southern Tailed Birdwing (Ornithoptera meridionalis, Rothschild 1897) is a butterfly with a high degree of sexual dimorphism. It is restricted to New Guinea, where it is an endangered and very localized species of lowland forest. It occurs mainly in south-eastern Papua New Guinea but is also known from Irian Jaya, Indonesia. It is threatened by increased extraction of timber from its localities, many of which are very accessible. Effective reserves are needed for O. meridionalis, which could be managed in part as tourist showpieces. Protected status for the species should be maintained.
The male Meridional Birdwing has tailed hindwings, a wingspan of 80-115 mm (3) and is black, iridescent yellow-green and golden. The male is, on average, much smaller than any other male Ornithoptera, including that of the closely-related O. paradisea. The female is considerably larger than the male, black with white and yellow markings (1, 2, 4, 6, 10).
The male upper forewing is similar to that of O. paradisea, black with broad, iridescent yellow-green radial and cubital bands and a short anal band. The upper hindwing is curved inwards and much reduced in size, tailed, with a small, diamond-shaped tip, a reduced black anal area and an extensive yellow-gold patch. The lower forewing is iridescent yellow-green, more golden than on the upper surface. Black scaling covers the veins, the narrow costal and outer margins, a large cubital patch and the wing apex. The lower hindwing is similar to the upper surface with a pale grey brush border and no black scaling (1, 2, 4, 6, 10).
In the female the forewing is black with white markings including a large cell spot, subapical streaks, submarginal spots and three large discal spots. The hindwing is rounded, black with a broad distal band, extending over the discal region and part of the cell. It is yellow and suffused with black scales on the distal side of a row of large, black subdiscal spots, and white on the discal side (1, 2, 4, 6, 10).
Ornithoptera meridionalis has been found only in the island of New Guinea. Until recently it was thought that the butterfly occurred only in Papua New Guinea. Females of a separate subspecies, tarunggarensis, occurring at Nomnangihe, 40 km south-west of Wanggar and highly disjunct with the Papua New Guinea populations, have been shown to be referable to O. paradisea, not O. meridionalis (3). However, O. meridionalis has been discovered to be truly present in Irian Jaya, in the region of Kamrau Bay about 200 km west of the Weyland Mountains, in the Weyland Mountains themselves and in the area around Lake Yamur (Jamur) to the east of the Weyland Mountains (3, 7, 9).
However, the name tarunggarensis has been most confusingly applied to these populations (7, 9). If, as seems likely, they represent a subspecies distinct from O. m. meridionalis, it lacks a valid name. O. meridionalis is quite widely distributed in mainland Papua New Guinea, but very local. Its main area of occurrence is along the southern part of the south-eastern peninsula, but it has also been recorded from single localities in the Southern Highlands and East Sepik Provinces. It has not been reported from any of the islands and is known from only fourteen 10 km squares in the country (8).
Habitat and Ecology
Ornithoptera meridionalis occurs mainly in lowland rain forest, both primary and mature secondary, usually between 20 and 200 m above sea level. However, it probably extends into hill forest if its foodplant is present. The specimen from the Southern Highlands Province was captured at 800 m (8). In the Kamrau Bay population in Irian Jaya, the butterfly is also a mainly lowland species, though one population was found to be established at about 700 m (9).
There is doubt as to the exact species of foodplants. Some accounts state that the larvae are monophagous on Aristolochia dielsiana (known in the literature as A. schlechteri), others that A. pithecurus (probably synonymous with A. momandul) is the main foodplant (5,6, 11, 12). Larvae in the Kamrau Bay area feed on A. dielsiana, a species of Aristolochia indistinguishable from A. schlechteri (9).
The male butterflies fly poorly and are less often seen than the males of other Ornithoptera species; this is evidently correlated with the small size and unusual shape of the hindwing (9). Adult females seem to fly mainly in their home range, although they have also been seen flying along tracks in open secondary forest (8).
Females deposit eggs singly on the undersides of the foodplant leaves. The eggs are large (3 mm diameter) and females carry very few, usually between five and seven (8, 11, 12). Females of the Kamrau Bay populations apparently do not oviposit on foodplants growing on steeply-sloping terrain. In this population, 50-60 per cent of eggs were attacked by parasitic flies (9), probably a species of Trichogramma (Hymenoptera: Chalcidoidea). The parasite was not observed to attack eggs of Ornithoptera priamus on the same foodplant and may be specific to O. meridionalis (9). Feeding by mature larvae is characteristic: the central disc of the leaf is eaten from the apex, leaving a crescent-shaped area uneaten. Both larvae and pupae have been described and figured (6, 11. 12).
Natural enemies of the larvae include birds, tree frogs, a species of lizard and invertebrates such as large reduviid bugs and spiders (9).
The Irian Jaya populations of O. meridionalis do not appear to be so much at risk as those of Papua New Guinea (8, 9). Indeed, it is probably the inaccessibility of the Irian Jaya localities, and paucity of human settlements, which has delayed their discovery. However, the Papua New Guinea populations are seriously threatened by habitat destruction and change. These low-lying localities are particularly subject to commercial extraction of timber. Some of the main areas of occurrence are close to Port Moresby and are accessible by road, an unusual circumstance in Papua New Guinea. Logging is increasing in the region of the Brown and Vanapa Rivers, which lie in the centre of the range of O. meridionalis in south-eastern Papua New Guinea (5,8).
Specimens of O. meridionalis are much in demand by collectors. The birdwing occurs only in New Guinea and is totally protected in Papua New Guinea. It is not protected in Irian Jaya, probably because the butterfly was so little known in that country until recently. No threats are known to be posed by illegal collecting and trade, nor by legitimate dealing. However, the butterfly is one of the most valuable known; a pair was offered in Britain for £650 in 1980 (13) and can be found on the internet today for upwards of Euros 900. It can be expected that commercial trade in specimens from Irian Jaya are being developed now that the localities are known there.
Because of the main threat to O. meridionalis in Papua New Guinea, the most important measure to be taken for the butterfly’s conservation is the establishment of National Reserve Areas under the Conservation Areas Act. The establishment of five reserves has been suggested, with priority given to the Brown and Vanapa Rivers areas (8). Because this area is easily accessible from Port Moresby, the capital of Papua New Guinea, conservation could be combined with a tourist attraction. Enrichment of the habitat should be considered by planting the host of O. meridionalis, Aristolochia dielsiana, as has been done for the common birdwings by planting A. tagala (8).
The other four reserves in Papua New Guinea suggested for O. meridionalis are at Lake Kutubu, the Frieda River, Cape Rodney and Mamai Plantation. At Lake Kutubu, located in the Southern Highlands, three uncommon birdwing species (Ornithoptera goliath, O. paradisea and O. meridionalis) could be conserved (8).
The Irian Jaya populations of O. meridionalis appear to lie mainly outside the boundaries of existing or proposed reserves. This exception may be the proposed Weyland Mountains Nature Reserve (Cagar Alam), which has been put forward to replace the unsuitable Enarotali Nature Reserve (14). Although the conservation of O. meridionalis in a national reserve in Irian Jaya is desirable, the recent discovery of the species in new areas suggests that survey and exploration are the first priorities.
In the long term, the future of O. meridionalis may be linked with its carefully controlled utilisation, both as a tourist showpiece, at least in Papua New Guinea, and as a sustainable resource of specimens (8). O. meridionalis is a totally protected species in Papua New Guinea, so that any controlled utilisation would require amending legislation. The butterfly is listed under Appendix II of the 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). This status should be retained. Appendix II listing implies that commercial trade is allowed, providing a permit from the country of export is obtained. If enforced, this can provide a method of monitoring the amount of trade.
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