The Philippine Archipelago is a series of Tropical Oceanic Islands located off the eastern edge of the Sunda Shelf. While dramatically lower sea levels of 145-160 in during the middle and late Pleistocene uncovered the shelf and joined the Malay Peninsula and islands of Sumatra, Java, and Borneo into one land mass (Heaney 1985), this had little effect on accessibility to the oceanic Philippine Islands. Although relatively narrow water gaps, 12-25 km in width, existed between the archipelago and the Sunda Shelf at several times during the middle and late Pleistocene, the only major island that was connected to the mainland was Palawan,(1) which formed part of Sundaland during the middle Pleistocene. Therefore nonarboreal mammalian fauna entering the archipelago either swam or were rafted to the oceanic islands.
This isolation, combined with the relatively small size of the islands, has had a significant effect on the mammalian fauna, affecting both species diversity and morphology. The water barrier acted as a filter, allowing migration of small mammals, particularly murid rodents, and discouraging migration of other taxa. Small insectivores, for example, have high metabolic requirements, which make it unlikely that they would survive a lengthy rafting event. Other research on island biogeography (Heaney 1984) has shown that small isolated islands, in general, support a fauna depauperate in carnivores and large herbivores. In contrast to the 11 species of ungulates and 29 species of carnivores on Sumatra, the Philippines supports only three species of ungulates and two species of carnivores (Heaney 1984).
Island size may have a direct impact on body size, especially of herbivores. Isolated herbivore populations surviving on islands may respond to environmental pressures specific to the island's ecology or, alternatively, respond to removal of pressures encountered in mainland environments by changing size (Foster 1964). Small herbivores tend to increase in size, while large herbivores often respond to range restrictions by decreasing in size. In the Philippines, conditions of isolation and small island size had a predictable effect on large herbivore fauna. The bearded pig (Sus barbatus) is significantly smaller than its counterpart in Borneo, a condition that probably developed after entry into the oceanic islands (Mudar 1986). The tamarao (Bubalus mindorensis), which is currently restricted to Mindoro, is probably the result of paedomorphic dwarfing of water buffalo, which entered the Philippines during the middle Pleistocene (C. Groves, personal communication 1996).
The water barriers and small sizes of the Philippine Islands have thus impacted the mammalian faunal composition by restricting entry of taxa and promoting a decrease in the size of the larger herbivores. The resulting fauna is generally impoverished and exhibits a high degree of endemism when compared to similar islands on the Sunda Shelf (Heaney 1985). This has had a significant effect on the extractive strategies of human populations exploiting terrestrial resources in the Philippines.
Compared to other regions of Southeast Asia, pigs and deer, which are the largest wild animals widely available for exploitation in the Philippines, are relatively small. Pigs weigh up to 200 kg, and deer up to 260 kg. In contrast, water buffalos and large bovids on the Southeast Asian mainland may weigh up to 1200 kg. Furthermore, there is no indication that indigenous domestication of Philippine mammalian taxa took place. As a result, large amounts of meat were not consistently available; the most reliable sources of animal protein may have been marine and freshwater fish.
The introduction of large domestic animals into the Philippines, therefore, may have altered the subsistence of both foraging and agricultural groups. Introduced domestic animals include the pig, water buffalo, horse, cat, dog, and goat. The domestic pig, and possibly the chicken, provided predictable access to small to moderate amounts of meat. …