Biological diversity in Northern Sierra Madre, Philippines: its implication for conservation and management
1993
Mallari, N.A.D. | Jensen, A. (Philippines Univ., Los Banos, College, Laguna (Philippines). Wildlife Biology Lab.)
Biological diversity in the Northern Sierra Madre [Philippines] mountains was evaluated using a combination of several survey techniques: namely, forty-hour line transect counting, mist-netting, general observations, bioacoustics, systematic trapping of non-volant mammals, and ethnobiological interviews with local people. In addition, information on existing land-use, logging practices, forest distribution and forest quality were compiled, together with a study focused on the Philippine Eagle. Thirteen study sites covering different forest types, habitat types and elevational gradients were identified. A total of 241 (200 breeding and 41 migratory) species of birds was identified. Nearly 80% of the breeding species known from Luzon have now been recorded. Eighty-seven percent of Luzon's Philippine endemics and 84% of all Luzon endemics are now known to occur in the area. This confirms the international importance of this mountain range as one of the 221 global key sites for conservation of biodiversity. Twenty-seven species of mammals (14 bats, 8 murid rodents, 1 monkey, 1 wild pig, 1 deer and 2 civets) were recorded, including 2 poorly known genera of rodents and a possibly undescribed species of bat. At present, about 70% of Luzon mammals are of unknown conservation status. It is evident that further reduction of the remaining primary forests and old residual forests in the mountain range will result in serious loss of biodiversity. And because of this and its limited distribution, the Isabela Oriole, Oriolus isabelae (not observed since 1961) maybe the first bird species endemic to the area that will face extinction. With the extinction of very vagile organisms such as some birds, it is apparent that organisms which are less vagile and thus, with low colonization capability, face greater threat of extinction
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