PART 2
BIODIVERSITY AND CONSERVATION IMPORTANCE

2.5 TERRESTRIAL WILDLIFE AND BIRDS

Information in this section comes from surveys carried out under the Semporna Islands Project (Davison, 1998; Lakim et al. 1998; Mohamed et al. 1999), with additional details from the 1980 survey report (Wood, 1981).

The central high islands of Bodgaya and Boheydulong have a much richer fauna than the small, outlying ones because they offer more space and shelter and a greater range of food and undisturbed habitats. Even so, the fauna on these central islands is generally impoverished in comparison with similar habitats on the mainland. This is to be expected, given the small land areas and fewer number of ecological niches, combined with isolation and chance extinctions.

Although the diversity and abundance of species recorded is relatively low, it is interesting to note the occurrence of long-tailed macaques, populations of bats in the numerous caves, an abundance of birds despite limited number of species recorded, and a variety of reptiles especially snakes and lizards. A solitary large (estimated 1.5m body length) monitor lizard (Varanus salvator) was observed swimming in mangrove habitat on Bodgaya. The natural island vegetation especially the abundance of figs that occur on Boheydulang and Bodgaya are thought to be important for supporting the current population of vertebrates.

Bodgaya and Boheydulang are refuges for a number of insect species that have never been recorded in any other part of Sabah including a couple which appear to be undescribed species.

Mammals

The commonest large mammal is the long-tailed macaque, Macaca fascicularis, which was also recorded during the 1980 survey. At least 2 groups occur in mangrove and forest areas on Boheydulang and another two on Bodgaya.

Local informants during the 1980 survey reported that the bearded pig (Sus barbatus) used to be common, but had become scarce. Its tracks were seen on both the main islands during the 1980 survey, but since then it has apparently been hunted to extinction. The sambhur deer (Cervus unicolor) has also suffered the same fate. A mouse deer (Tragulus) was seen on Bodgaya in 1999 by one of the survey teams, but the size of the population of these small forest-dwelling mammals is unknown.

Tracks of an otter (Lutra sp) were seen in mangrove on Bodgaya during the 1980 survey, and groups of up to 12 animals were seen sporadically around the old Pearl Farm on Boheydulang during the Semporna Islands Project. They emerged from the mangrove to hunt along the shallow back reef.

The nest of an unknown squirrel species was seen on a coconut tree on Bodgaya, and 'black squirrels' (possibly Callosciurus prevostii) have been seen on Boheydulang near to the old Pearl Farm. The rat (Rattus rattus) is also present here.

Three species of bats (Ronsettus amplexicandatus, Megaderma spasma and Hipposideros cervinus) occur on the main islands (in comparison with 64 species that occur on the mainland). All these are insectivorous, and shelter in the many caves that occur on the two large islands. The largest population of the three species was R. amplexicaudatus. The roost of this species, a large cave (40 m height x over 20 m length) situated on the east side of Boheydulang Island, was estimated to hold more than a thousand individuals (Lakim et al. 1998).

Apart from wild vertebrate fauna, domestic mammals such as dogs, goats and cats have been introduced by local residents to Boheydulang and Bodgaya.

Birds

A total of 48 species comprising mainly resident birds have been recorded from the area (Davison, 1998; Lakim et al. 1998). The shallow seas should attract a number of seabirds, but there have been few observations to date. An interesting zoogeographical feature is the distinction between the bird fauna of the Semporna Islands and the Sulu Islands. Even though the maximum distance between any two islands is about 16 km, the gap between Sibutu and the Semporna Islands includes a deep sea trench which has evidently been an effective barrier to landbird dispersal during the Pleistocene. Sulu Hornbill, and Manatanani Scops-owl are two examples of about 20 species and subspecies that have not made it across to Sabah territory (Davison, 1998).

Of the families recorded on and around the Semporna islands, pigeons and doves (Columbidae) are particularly well represented - a typical feature of small islands. Pied Imperial Pigeon (Ducula bicolor) was the most common understory species observed in the forested area of Boheydulang and Bodgaya. Flocks of this species containing more than 20 individuals were observed in trees on several occasions. Both the metallic pigeon Columba vitiensis and Nicobar pigeon Caloenas nicobarica occur on the islands and are of particular conservation interest.

Tabon scrubfowl (megapodes- Megapodius cumingii) were observed on Boheydulang. These ground-dwelling birds are also of conservation interest, since their nests are often raided for eggs. Five active nesting mounds were found during a survey on Boheydulang, indicating the presence of a healthy breeding population (Lakim et al. 1998).

Other distinctive birds include the birds include the collared kingfisher Todirhamphus (Halcyon) chloris and the pied hornbill Anthracoceros albirostris. Sea eagles and other raptors, thrushes, flycatchers, sunbirds and bulbuls were also recorded. Shore birds were typically uncommon but included the common sandpiper (Tringa hypoleucos), striated heron (Butorides striatus) and lesser frigatebird (Fregata ariel).

Reptiles and amphibians

Surveys of reptiles and amphibians were carried out by the Sabah Museum (Wong, 1998), with additional information from Sabah Parks (Lakim et al 1998). The herpetofauna in the Semporna Islands is distinctly impoverished compared to the mainland, with fewer species and lower population density except for sea snakes. The central high islands of Bodgaya and Boheydulang have a richer fauna than the small, outlying ones because the bigger islands offer more space and a greater range of undisturbed habitats and food supplies.

No rare or endangered species of herpetofauna were found, but snakes and lizards were common. Five species of terrestrial snake were found (including pit vipers Trimeresurus spp., reticulated python Python reticulatus , green vine snake, Ahetula prasina and dog-toothed cat snake Boiga cynodon) together with at least six species of sea snake. Sea krait Laticauda colubrina are common around the jetty on Boheydulang, while the other species occur offshore.

Skinks and lizards, including the common water monitor lizards occur on the main islands. The most conspicuous of the lizards is the large tokay (Gekko gekko - Figure 37). Amphibians are apparently absent from the proposed park area, presumably due to the difficulty of reaching the islands, and the lack of permanent rivers or large pools for breeding.

Insects

Insects were investigated by the Sabah Museum (Lakim et al. 1998) and the Universiti Malaysia Sabah (Mohamed et al. 1999).

Butterflies (Lepidoptera) were particularly well represented, with a total of 52 species collected. This is about 5% of the Borneo fauna and is considered to be high diversity for the size of the islands. Some of the butterflies collected were a new record of species occurrence from Sabah (Otsuka, 1988; Kazuhisa Otsuka, pers. comm.). Moreover, one species from each family of Nympharidae and Pieridae are probably new species. These findings revealed the uniqueness of insect fauna in the area.

Beetles (Coleoptera), sucking insects of herbaceous plants (Hemiptera and Homoptera) and stinging insects (Hymenoptera) were also fairly common, and showed reasonable diversity but diversity of ant species was very poor.