This EBA includes the lowlands and mountains of Luzon-at over 100,000 km² the largest of the Philippine islands-and the associated islands of Polillo, Marinduque and Catanduanes. The Batanes and Babuyanes Islands to the north of Luzon are treated separately as a Secondary Area (s094). On Luzon there are three main mountain ranges which are important for restricted-range birds: in the west, the Cordillera Central (including Mts Puguis, Polis, Data and Pulog-the highest peak at 2,930 m) and the Zambales Mountains, and in the east the Sierra Madre; other isolated mountains of note include Mts Banahaw and Isarog further south.

Various different forest types can be recognized in the Philippines including tropical lowland evergreen rain forest which is rich in dipterocarps; this grows best on good soils and therefore is (or was) prevalent on well-watered plains and the lower slopes of hills up to c.400 m, occasionally higher, giving way to a more open, dipterocarp-dominated, montane rain forest at c.650-1,000 m and upwards. Mossy forest, where the trees are dwarf, moss-covered and laden with ferns, orchids and liverworts, occurs in the cloud belt where there is constant high humidity, usually over 1,200 m, but also on exposed summits and ridges at lower elevations, and as low as 700 m in the eastern Sierra Madre where it is wettest. Extensive stands of Benguet pine Pinus kesiya occur in the western Cordillera Central and Zambales Mountains between 450 and 2,450 m where it is drier (Dickinson et al. 1991, Collins et al. 1991).

In some parts of Luzon there are large areas of dense 'cogon' grassland; these areas are maintained by fire during the dry season and are all thought to have replaced original forest (Dickinson et al. 1991).

The majority of the restricted-range species occur in forest, with three being (or likely to be) grassland birds. The forest species can be divided into those which tend to occur in lowland and hill forest (largely below 1,000 m) and those which tend to occupy montane and mossy forest (largely above 1,000 m); see 'Habitat associations' table. Although only 'lowland' species are found on the smaller islands, nearly all of the restricted-range species occur in the Cordillera Central and/or the Sierra Madre (see 'Distribution patterns' table). Because of these distributional similarities and some altitudinal overlap between those birds classified as 'lowland' and those as 'montane', all restricted-range species occurring on Luzon have been included within this single EBA (contra ICBP 1992); a similar treatment has been applied to Mindanao (EBA 154), the second largest island in the Philippines.

The distributions of most species in this EBA appear to be patchy but this is largely because of forest fragmentation and it is likely that ranges were once more widespread and contiguous even in historical times. In addition, recorded distributions are dependent on observer coverage (which is still incomplete), and present-day ranges for some species may be larger in reality than is currently apparent. Because it has been difficult to determine which species genuinely qualify as having ranges of less than 50,000 km², all species which are endemic to Luzon (apart from one-lowland White-eye Zosterops meyeni, a widespread habitat generalist) have been included as restricted-range, despite the large size of this island.

Knowledge of some species has been improved by recent surveys: one in the Sierra Madre recorded three very poorly known birds Rhabdornis grandis, Napothera rabori and Pitta kochi (Danielsen et al. 1991, see also Mallari and Jensen 1993)-and another in Mount Pulog National Park in the Cordillera Central found that area probably to be a stronghold for Rhyacornis bicolor (Andersen et al. 1992). Two species which remain, however, very little known are Lewinia mirificus and Turnix worcesteri, with records of these appearing mostly to be individuals involved in post breeding-dispersal or on migration.

In addition to its many resident restricted-range species, four restricted-range species occur on Luzon as wintering birds: Japanese Night-heron Gorsachius goisagi from the lowland forests of central Honshu in Japan (Secondary Area s089), Ijima’s Leaf-warbler Phylloscopus ijimae from the Izu Islands of Japan (EBA 146), Streaked Reed-warbler Acrocephalus sorghophilus from China (breeding grounds unknown), and Yellow Bunting Emberiza sulphurata from the montane forests of central Honshu (Secondary Area s090).

This EBA was once completely forested but satellite data from 1988 show forest covering just 24% of Luzon, 3% of Marinduque and 26% of the Catanduanes (Dickinson et al. 1991). The Sierra Madre has one of the largest remaining forest blocks (and one of the richest avifaunas yet known from any forest area in the Philippines) but even there much forest has been lost: it has been estimated that 40,000 km² of primary lowland forest remained in the 1930s, but this has been reduced to only 6,850 km² (17%), and most areas are under logging concessions (Mallari and Jensen 1993, Poulsen 1995).

Upland mossy forests, though more secure than lowland ones, are subject to threat, especially in the Cordillera Central where local people have recently accepted modern technology and are growing temperate and semi-temperate vegetable crops on bench terraces after clearance of native montane habitats (Penafiel 1993).

Several restricted-range species in this EBA are hunted for food or for the cage-bird trade, but the main threat to birds comes inevitably from continuing forest loss and fragmentation. For example, Oriolus isabellae, which may be close to extinction. This species was known only from the Bataan peninsula and Isabela province, with one of the last records from a site in the Sierra Madre in 1961-where there is now virtually no forest (Danielsen et al. 1994); more recently there have been records from two further sites in the Sierra Madre in Quirino and Cagayan provinces, although the former was in a small fragmented forest area of less than 100 km² (Gamauf and Tebbich 1995, van der Linde 1995).

Overall, no other Asian island has as many threatened bird species as Luzon, for-as well as the 18 threatened restricted-range species which breed there, and the four threatened restricted-range species (from other EBAs and Secondary Areas) which occur as winter visitors (all classified as Vulnerable; see 'Restricted-range species', above)-there are nine additional widespread threatened species found in Luzon’s forests. These latter include the Philippine Eagle Pithecophaga jefferyi (classified as Critical, with the forests of the Sierra Madre representing the species' largest single remaining stronghold: Danielsen et al. 1992), 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) and Black-bibbed Cicadabird Coracina mindanensis (Vulnerable).

There are several protected areas which cover the main mountain ranges in Luzon (e.g. Mts Data, Pulog, Banahaw-San Cristobal and Isarog). The Northern Sierra Madre Protected Area (which includes the Palanan Wilderness Area) has recently been established under the Integrated Protected Areas System (IPAS) and is a critical extension of this network. The watershed at Angat dam (which is not gazetted) and Quezon National Park are two lowland sites which are of prime importance to bird conservation (Lambert 1993a), and the lowland forest in the Subic Bay protected area, also established under IPAS, is another important tract.

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Luzon. Downloaded from https://datazone.birdlife.org/eba/factsheet/150 on 22/11/2024.