The major part of this EBA is the lowlands and mountains of Mindanao, at just under 100,000 km² the second largest Philippine island after Luzon (EBA 151); also included are the islands of Samar, Leyte and Bohol (which are politically part of the Visayas; see also EBAs 152, 153), and associated islands such as Biliran, Dinagat, Siargao, Camiguin Sur and Basilan.

The mountain ranges of Mindanao form three main uplands: those east of the Agusan river including Mt Hilong Hilong in the Diuta range and Mt Mayo in the south-east; the central uplands with major peaks such as Mts Katanglad, Apo and Matutum; and the mountains of the Zamboanga peninsula including Mts Malindang and Sugarloaf.

Various different forest types can be recognized, including lowland evergreen rain forest up to c.400 m, which gives way to a more open forest at higher elevations between c.650 and 1,000 m; in the cloud belt above, usually at over 1,200 m, is mossy forest (Collins et al. 1991, Dickinson et al. 1991). These vegetational zones can vary, e.g. on Mt Katanglad where they appear to be significantly higher.

All the restricted-range species of this EBA are forest birds. Although some have been recorded from degraded or selectively logged or secondary forest, the long-term survival of all is likely to depend on proximity to primary habitat.

Species can be divided into those which tend to occur in lowland and hill forest (largely below 1,000 m), and those which prefer montane and mossy forest (largely above 1,000 m). Although only 'lowland' species occur on the smaller islands (with three species being confined to Samar, Leyte and Bohol only), there are many distributional similarities and some altitudinal overlap on Mindanao between those species classified as 'lowland' and those as 'montane', and thus all these restricted-range species have been included within this single EBA (contra ICBP 1992; a similar treatment has been applied to Luzon, the Philippines' largest island, see EBA 151).

For many species, the distribution in this EBA appears to be patchy (see 'Distribution patterns' table) but, for some species at least, this may be because recorded distributions are dependent on observer coverage (which is still incomplete), and actual ranges may therefore be larger and more contiguous than is apparent from published sightings. Because of the difficulty in determining range size all species which are endemic to Mindanao have been included as having restricted ranges.

The islands of this EBA were originally completely forested but satellite data from 1988 show forest covering only 33% of Samar, 14% of Leyte, 6% of Bohol, and 29% of Mindanao (Dickinson et al. 1991). These figures are, however, likely to be overestimates (T. Fisher per G. C. L. Dutson in litt. 1993), and most of the accessible (=lowland) forest estate outside the protected area system is leased to private timber companies for logging (Collins et al. 1991). Aerial surveys of Basilan in 1992 revealed that old-growth forest had been reduced to only c.2 km² (less than 0.2% of the island), indicating a further massive reduction from the 180 km² (14%) estimated from the 1988 satellite data (W. L. R. Oliver in litt. 1996).

Many species have undoubtedly undergone rapid and continuing declines with the loss of their habitat, particularly those species which rely on primary lowland forest, and consequently the majority of the EBA's restricted-range species are classified as threatened (22 in all, a greater number than in any other EBA of the south-east Asian island region) or Near Threatened. Many species appear to be very scarce having been recorded very little in recent years, e.g. Aceros leucocephalus and Alcedo argentata.

Species which occur in mossy forest are more secure as these forests are often found in extremely rugged and inaccessible mountains that contain few commercial tree species and are generally too steep for agricultural purposes. However, the recent discovery of gold in the mountains of eastern Mindanao could be a serious threat, with some of the lower slopes having already been totally destroyed (Kennedy et al. 1997).

Other widespread threatened forest birds which occur in this EBA include the Philippine Eagle Pithecophaga jefferyi (Critical; found in rain forest on the islands of Luzon, Samar, Leyte and Mindanao), Philippine Hawk-eagle Spizaetus philippensis (Vulnerable), Spotted Imperial-pigeon Ducula carola (Vulnerable), Philippine Cockatoo Cacatua haematuropygia (Critical), Blue-naped Parrot Tanygnathus lucionensis (Endangered), Philippine Eagle-owl Bubo philippensis (Endangered), Philippine Kingfisher Ceyx melanurus (Vulnerable), Rufous-lored Kingfisher Todirhamphus winchelli (Endangered) and Black-bibbed Cicadabird Coracina mindanensis (Vulnerable).

There are several protected areas within the EBA including the Rajah Sikatuna National Park on Bohol (90 km², an important site which includes most of the remaining natural forest on the island: Lambert 1993a, Brooks et al. 1995c). On Mindanao, there are national parks at Mts Apo (720 km²) and Malindang (534 km²) which have rain forest within their boundaries. As well as being important for restricted-range species, these parks harbour small populations of Pithecophaga jefferyi. However, there is no effective management of the Mt Apo National Park, and massive human encroachment, even into the uplands, has destroyed large areas of both lowland and montane forest such that probably over 50% of the original park is now deforested; similar problems affect the Mt Malindang National Park (Lewis 1988, Collins et al. 1991; see also Myers 1988b). The construction of a geothermal power station and access road has also threatened the integrity of the Mt Apo National Park. On Basilan, there is a national park (31 km² ) but, given the recent reduction in forest, this has afforded no protection. There are no recent data on the status of birds (or other wildlife) owing to the intensification of political insurgency on the island, which seems destined to lose most of its endemic taxa if action is not taken in the near future (W. L. R. Oliver in litt. 1996).

Siargo, Agusan Marsh and Mt Katanglad have recently been protected under the Integrated Protected Areas System (IPAS). Mt Katanglad has been identified as one of the most important sites for endemic birds in Mindanao and has one of the richest Philippine avifaunas yet documented, despite the fact that observations in 1993 indicated that the Katanglad range rarely has forest below 1,000 m, and in many place no forest below 1,400 m. The park is under threat from illegal commercial logging, clearing for slash-and-burn agriculture ('kaingin'), and overhunting and collecting of wildlife (Heaney et al. 1993, Lambert 1993a).

Many lowland species are still in good numbers in commercial logging concessions of, for example, PICOP Resources Inc. (formerly the Paper Industries Corporation of the Philippines) near Bislig, and, if these areas remain intact, they may be the best hope for these species' survival (T. Fisher per G. C. L. Dutson in litt. 1993).

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Mindanao and the Eastern Visayas. Downloaded from https://datazone.birdlife.org/eba/factsheet/155 on 22/11/2024.