The Philippine islands hold a concentration of species diversity and endemism of global
importance, yet few studies have analyzed biogeographic patterns or attempted to
prioritize areas for conservation within the archipelago. We analyzed distributions of 386
species on 28 Philippine islands and island groups, documenting intense concentration of
species richness, especially of endemic species, on the two largest islands, Mindanao and
Luzon. Factors identified as influencing species richness included island area, maximum
elevation, and Pleistocene patterns of connection and isolation. Reserve systems were
developed based on heuristic complementarity algorithms, and compared with the
existing Integrated Protected Areas (IPAS) system in the country, showing that IPAS is
an impressive first step towards protecting avian diversity in the country. Addition of
presently proposed reserves on Palawan and Mindoro would make IPAS a near-optimal
reserve design, at least at the level of island representation. Important challenges remain,
however, with regard to design of reserve systems within islands to represent complete
island avifaunas
