Location and General Description
This ecoregion represents the moist forests on Halmahera, Morotai, Obi, Bacan, and the other nearby Maluku Islands in the northeastern Indonesian Archipelago. Based on the Köppen climate zone system, this ecoregion falls in the tropical wet climate zone (National Geographic Society 1999). The geologic history of these islands is a very complex mixture of inner volcanic island arcs, outer volcanic island arcs, raised coral reefs, and fragments of continental crust. Halmahera is a product of a collision between two islands approximately 1-2 million years ago. The eastern half of the island was part of an outer arc on the Philippines tectonic plate and consists of sedimentary and intrusive igneous rocks. The western half of Halmahera and Morotai was part of an inner arc consisting of volcanic materials. Bacan is a mixture of volcanic inner island arc and some crustal materials (Monk et al. 1997).
The natural vegetation of these islands was tropical lowland evergreen and semi-evergreen forest (Stattersfield et al. 1998). Most of the remaining habitat in this ecoregion is semi-evergreen rain forest and includes eight characteristic dipterocarp species: Anisoptera thurifera, Hopea gregaria, H. iriana, H. novoguineensis, Shorea assamica, S. montigena, S. selanica, and Vatica rassak. Volcanic soils and good aspect combine to produce almost optimal growth conditions. Most of the trees reach 30 m or more and carry thick-stemmed lianas and woody and herbaceous epiphytes. Rattans that grow to 130 m and other epiphytes are common in old-growth forests. The most luxuriant rain forests occur in northwest Morotai and north Halmahera, as opposed to the south arm of Halmahera, which is in the rain shadow of north Halmahera and Bacan. Low, shrubby vegetation is found in poor soil conditions on patches of ultrabasic rocks (Monk et al. 1997).
Overall diversity is low in this ecoregion, but overall endemism is moderate to high when compared with that of other ecoregions in Indo-Malaysia. This ecoregion falls within the Wallacean biogeographic zone, and thus exhibits a mixture of Asian and Australian fauna. Together with Seram, Buru, and the Banda Sea Islands, this island group forms part of a bioregion with perhaps the highest levels of bird endemism for its size anywhere in the world and the highest number of endemic birds of any area in Asia.
The mammal fauna is depauperate, containing only thirty-eight species with both Asian and Australasian affinities (cuscuses), but includes eight ecoregional endemics (table 1). The Obi cuscus (Phalanger rothschildi) is considered vulnerable (IUCN 2000).
Table 1. Endemic and Near-Endemic Mammal Species.
Phalangeridae Phalanger ornatus*
Phalangeridae Phalanger rothschildi*
Phalangeridae Phalanger sp.*
Pteropodidae Pteropus chrysoproctus
Pteropodidae Pteropus personatus*
Pteropodidae Nyctimene minutus
Muridae Melomys obiensis*
Muridae Rattus sp.*
An asterisk signifies that the species' range is limited to this ecoregion.
The ecoregion supports approximately 223 bird species, including 43 ecoregional endemic species (table 2). The ecoregion corresponds with the Northern Maluku EBA. There are four endemic monotypic genera: Habroptila, Melitorgrais, Lycocorax, and Semioptera. These species include the invisible rail (Habroptila wallacii), white-streaked friarbird (Melitograis gilolensis), paradise-crow (Lycocorax pyrrhopterus), and the standardwing (Semioptera wallacii). Of the forty-three restricted-range species found in this ecoregion (and EBA), an astounding twenty-six are found nowhere else in the world. Five vulnerable species, four of which are found nowhere else, are found in the ecoregion: invisible rail (Habroptila wallacii), caranculated fruit-dove (Ptilinopus granulifrons), chattering lory (Lorius garrulus), and white cockatoo (Cacatua alba) (Stattersfield et al. 1998).
Table 2. Endemic and Near-Endemic Bird Species.
Family Common Name Species
Accipitridae Moluccan goshawk Accipiter henicogrammus*
Accipitridae Rufous-necked sparrowhawk Accipiter erythrauchen
Megapodiidae Moluccan scrubfowl Megapodius wallacei
Megapodiidae Dusky scrubfowl Megapodius freycinet
Rallidae Invisible rail Habroptila wallacii*
Scolopacidae Moluccan woodcock Scolopax rochussenii*
Columbidae Scarlet-breasted fruit-dove Ptilinopus bernsteinii*
Columbidae Blue-capped fruit-dove Ptilinopus monacha*
Columbidae Grey-headed fruit-dove Ptilinopus hyogastra*
Columbidae Carunculated fruit-dove Ptilinopus granulifrons*
Columbidae White-eyed imperial-pigeon Ducula perspicillata
Columbidae Spice imperial-pigeon Ducula myristicivora
Columbidae Pink-headed imperial-pigeon Ducula rosacea
Columbidae Cinnamon-bellied imperial-pigeon Ducula basilica*
Psittacidae Moluccan hanging-parrot Loriculus amabilis
Cacatuidae White cockatoo Cacatua alba*
Loriidae Violet-necked lory Eos squamata
Loriidae Chattering lory Lorius garrulus*
Cuculidae Moluccan cuckoo Cacomantis heinrichi*
Cuculidae Pied bronze-cuckoo Chrysococcyx crassirostris
Cuculidae Goliath coucal Centropus goliath*
Strigidae Moluccan hawk-owl Ninox squamipila
Aegothelidae Moluccan owlet-nightjar Aegotheles crinifrons*
Alcedinidae Blue-and-white kingfisher Todirhamphus diops*
Alcedinidae Sombre kingfisher Todirhamphus funebris*
Coraciidae Purple roller Eurystomus azureus*
Pittidae Ivory-breasted pitta Pitta maxima*
Meliphagidae Olive honeyeater Lichmera argentauris
Meliphagidae White-streaked friarbird Melitograis gilolensis*
Meliphagidae Dusky friarbird Philemon fuscicapillus*
Pachycephalida Drab whistler Pachycephala griseonota
Monarchidae White-naped monarch Monarcha pileatus
Monarchidae Moluccan flycatcher Myiagra galeata
Corvidae Long-billed crow Corvus validus*
Paradisaeidae Paradise-crow Lycocorax pyrrhopterus*
Paradisaeidae Wallace's standardwing Semioptera wallacii*
Oriolidae Halmahera oriole Oriolus phaeochromus*
Campephagidae Moluccan cuckoo-shrike Coracina atriceps
Campephagidae Halmahera cuckoo-shrike Coracina parvula*
Campephagidae Pale-grey cuckoo-shrike Coracina ceramensis
Campephagidae Rufous-bellied triller Lalage aurea*
Zosteropidae Cream-throated white-eye Zosterops atriceps*
Dicaeidae Flame-breasted flowerpecker Dicaeum erythrothorax
An asterisk signifies that the species' range is limited to this ecoregion.
The world's largest bee-the rare, 4-cm Wallace's giant bee Chalocodoma pluto-is also found on Bacan, Tidore, and Halmahera. Wallace discovered this species in 1858, and it was thought to be extinct until 1981, when it was recollected. This ecoregion also has conservation importance for butterflies and includes Troides aesacus, which may be the most primitive member of the T. priamus species group (Whitten and Whitten 1992; K. Monk, pers. comm., 2000).
The rich volcanic soils of Ternate, Tidore, and nearby islands have been aggressively cultivated for cloves and other spices for centuries (Stattersfield et al. 1998). From the 1920s through the 1970s, commercial logging and enforced cultivation depleted the forests of Halmahera and Morotai (Monk et al. 1997). On Morotai, large tracts of lowland rain forest were cultivated with papaya (Carica papaya) during World War II (Monk et al. 1997). Currently, the wet evergreen lowland forests in the northwest of Halmahera are exploited by logging companies, primarily for the valuable damar trees (Agathis) (Whitten and Whitten 1992). The eastern forests are threatened by pulp plantations, especially using local transmigrants.
Extensive habitat blocks still cover all the islands, with only small areas near the coast cleared for human settlements (Monk et al. 1997). The seven protected areas cover 4,880 km2 (18 percent) of the ecoregion area (table 3). Three protected areas are greater than 1,000 km2 in area, and the average size is 697 km2.
Table 3. WCMC (1997) Protected Areas That Overlap with the Ecoregion.
Protected Area Area (km2) IUCN Category
Waya Bula 830 PRO
Lolabata 1,210 PRO
Gunung Gamkonora 110 PRO
Ake Tajawi 1,200 PRO
Saketa 1,100 PRO
Gunung Sibela 300 PRO
Pulau Obi 130 PRO
Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.
Types and Severity of Threats
With nearly 80 percent of its original forest still intact, the Halmahera Rain Forests [AA0106] ecoregion is largely free of intense habitat conversion threats. However, as the forests are lost on other Indonesian islands, there is an increasing potential for commercial forestry operations to move to Halmahera. A mining company, PT Halmahera Mineral (NHM), has already obtained an exploration license for Bacan and "neighboring islands" to look for gold and other minerals. A Canadian mining company has a license to mine nickel near Ake Tajawi on Halmahera (K. Monk, pers. comm., 2000).
Justification of Ecoregion Delineation
The Sula Islands were included within the Sulawesi Lowland Rain Forests [AA0123], and the Aru islands in the Vogelkop-Aru Lowland Rain Forests [AA0128]. Buru Island, identified as a distinct subunit (13c) by MacKinnon (1997) and as an EBA (Stattersfield et al. 1998), was delineated as a distinct ecoregion, the Buru Rain Forests [AA0104]. Seram, the larger island to the east of Buru, was also delineated as an ecoregion: Seram Rain Forests [AA0118]. The larger Halmahera Rain Forests [AA0106] ecoregion includes Obi Island, which MacKinnon (1997) recognized as a separate subunit (13b) from Halmahera Island (subunit 13a). We created the Banda Sea Islands Moist Deciduous Forests [AA0102] by combining the islands in the Kai and Tanimbar archipelagos, which were distinguished as a biogeographic unit by Monk et al. (1997). The primary vegetation on the islands in both these archipelagos is moist deciduous forests and semi-evergreen forests, whereas the vegetation in the other, nearby large islands (Seram and Aru) is evergreen rain forests (Monk et al. 1997).
References for this ecoregion are currently consolidated in one document for the entire Indo-Pacific realm.
Indo-Pacific Reference List
Prepared by: John Morrison
This text was originally published in the book Terrestrial ecoregions of the Indo-Pacific: a conservation assessment from Island Press. This assessment offers an in-depth analysis of the biodiversity and conservation status of the Indo-Pacific's ecoregions.