This EBA comprises the northern chain of the Lesser Sunda islands from Lombok to Alor, in Nusa Tenggara Barat and Nusa Tenggara Timur provinces of Indonesia. These are mountainous islands with numerous volcanoes, many of which are active. Mt Rinjani on Lombok at 3,726 m is by far the highest mountain in the Lesser Sundas, and the mountains on Sumbawa and Flores rise to well over 1,000 m.

The Lesser Sunda Islands are relatively dry (in comparison to the rest of Indonesia) because they lie in the rain-shadow of the Australian continent and receive little rain in the south-east monsoon between April and November; most rain falls during the westerly monsoon in December to March. As a result, the natural vegetation of much of the EBA is deciduous monsoon forest. However, the south-facing sides of the mountains receive moderately high rainfall from onshore winds, and support isolated pockets of tropical semi-evergreen rain forest (Whitmore 1984). Montane forest is present above c.800 m (see map).

The restricted-range species of this EBA-which include the monotypic endemic genus Caridonax-are almost all forest birds, but their precise habitat requirements are not fully understood. The results of recent fieldwork on Sumbawa and Flores by Butchart et al. (1996) have, however, added considerably to current knowledge.

Eight species appear to be mainly confined to the lowlands below c.1,000 m, including Corvus florensis, which is known only from the western half of Flores. Todirhamphus australasia and Dicaeum maugei have an unusual disjunct distribution, being found in this EBA only on the western island of Lombok, but also to the east and the south in the other Lesser Sunda EBAs (163-165). Nine species appear to be particularly associated with the pockets of semi-evergreen rain forest found on the mountain slopes of Lombok, Sumbawa and Flores. These include Loriculus flosculus and Monarcha sacerdotum, which are endemic to Flores and known only from Tanjung Kerita Mese in the west of the island, and the former also from Mt Egon in the east, where they have been recorded below c.1,000 m. Nine species occur in both lowland and montane forest. The remaining three species are confined (in this EBA) to montane forests above c.1,000 m on Sumbawa and Flores. One of these, Otus alfredi, is known by three specimens collected at c.1,050 m on Flores in 1896, and was considered a form of the widespread Moluccan Scops-owl O. magicus by Sibley and Monroe (1993).

Forest clearance, carried out largely to permit shifting cultivation, and the practice of burning in the dry season have had a major impact on the natural vegetation of this EBA, and much of the region's landscape now consists of grassy hills, with forest surviving only in steep valleys and on the highest peaks (FAO 1982c). Lomblen, Pantar and Alor are described as having been devastated by cultivation (White and Bruce 1986), but some extensive areas of forest, including lowland semi-evergreen rain forest, remain on Lombok, Sumbawa and Flores (RePPProT 1990, Collins et al. 1991, Butchart et al. 1996). The forests in parts of south-west Sumbawa are threatened by a new gold and copper mine (Jepson and Monk 1995).

The three restricted-range species which are endemic to Flores are classified as threatened, because they all have particularly small ranges and are vulnerable to habitat loss. A more widespread threatened species (found throughout much of Wallacea) which occurs in the EBA is Yellow-crested Cockatoo Cacatua sulphurea (classified as Endangered), which is declining throughout its range because of a combination of habitat loss and unsustainable levels of trapping for the bird trade. The world's largest lizard, the Komodo dragon Varanus komodoensis, is endemic to this EBA, being found on Komodo, Padar and Rinca islands between Flores and Sumbawa, and very locally on Flores.

There are gazetted protected areas in most parts of this EBA, the most important for the restricted-range birds being the large Gunung Rinjani National Park on Lombok, Tambora Selatan and Pulau Moyo Hunting Reserves on Sumbawa, Ruteng Nature Reserve on Flores, which protects an important area of montane forest, and Tuti Adagae Recreation Forest on Alor. However, the total area protected is well below 10%, and some habitat types are not adequately represented, most notably semi-evergreen rain forest, but also montane forest and lowland monsoon forest. Several new protected areas have been proposed, the most important being Tanjung Kerita Mese and Egon Iliwuli because these include the only areas of semi-evergreen rain forest where two of the Flores endemic birds have been recorded. The other proposed areas are Selalu Legini, Puncak Ngenges (Gunung Olet Sangenges), Gunung Tambora Utara and Kompleks Hutan Dompu on Sumbawa (see Jepson and Monk 1995), and Gunung Ambulombo and Hutan Lewotobi on Flores (FAO 1982c, Sujatnika and Jepson 1995).

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Northern Nusa Tenggara. Downloaded from https://datazone.birdlife.org/eba/factsheet/162 on 22/11/2024.