This IBA includes the forests that extend from Subic Bay National Park up the north-western slope of Mt Natib in Bataan National Park, the highest point at 1,253 m. These are one of the few remaining undisturbed forests in the Zambales biogeographic zone, and some of the few surviving forests on Luzon that face the South China Sea (those in the Sierra Madre to the northeast facing the Pacific Ocean are different in character). The lowlands around Subic Bay National Park are now predominantly agricultural land and human settlements. The lower slopes of the mountains are covered by grasslands and croplands and secondary growth. Old growth forest is mainly confined to the steep slopes and gullies at higher altitudes. Lowland dipterocarp forest is found at c.100-900 m and montane forest above about 900 m. Between 3,000 to 5,000 ha of primary lowland dipterocarp forest is estimated to remain in the watershed, although much of this was damaged by the Mt Pinatubo eruption in 1992. Much of this forest was formerly included in the Subic Military Reservation, which was under US Navy control until 1993 when it was turned over to the Philippine Government and became Subic Bay National Park. The portion of the Subic Military Reservation under the control of the US navy was well protected, but the lowland forests here are of great commercial value and the land is under considerable pressure from a variety of economic developments. Under a new administration, the Subic Bay Metropolitan Authority, there was a boom of new industries within the reservation. The former military base has been transformed into a center for trade and industry. The forests of this IBA are a vital watershed for the communities living around the park. They are the home of indigenous communities of Aetas and Negritos, who survive within the boundaries of Subic Bay National Park.
Several of the threatened and restricted-range birds of the Luzon Endemic Bird Area have recently been recorded in this IBA, and the relatively extensive forests which remain there support important populations of several of these species, notably Green Racquet-tail. One of the largest recent counts of Philippine Duck was in Subic Bay.
Non-bird biodiversity: The northern Luzon giant cloud rat Phloeomys pallidus, golden-crowned flying fox Acerodon jubatus, Philippine brown deer Cervus mariannus and Philippine warty pig Sus philippensis are known to occur in the area, but surveys of the mammals and herpetofauna of the area are incomplete.
BirdLife International (2020) Important Bird Areas factsheet: Bataan Natural Park and Subic Bay Forest Reserve. Downloaded from http://www.birdlife.org on 20/10/2020.