History of introduction, population status, and management of Philippine deer (Cervus mariannus) on Micronesian Islands

Introduced populations of Philippine deer (Cm us mariannus) occur on four i slands in Micronesia: Guam, Rota, and Saipan in the Mariana Islands, and Po hnpei in the Caroline Islands. Deer were initially taken to Guam in 1771 or 1772, followed by introductions on Rota in about 1880, Saipan in 1900, and Pohnpei probably in 1904 or 1905. Two failed attempts to create population s occurred on Pohnpei in 1880 and on Tinian, Mariana Islands, in the early 1960s, where animals survived until about 1980. Historic trends in errant C . mariannus populations have varied in relation to hunting intensity and th e clearing of forested habitats. Currently, deer abundance appears to be ex panding on Guam, and is stable or declining on Rota, Saipan, and Pohnpei. P opulation estimates are not available for any island, but numbers are proba bly largest on Guam, with the highest densities found on several military i nstallations. Hunting occurs extensively on each island and is a major sour ce of mortality. Regulated hunting seasons exist on Guam and Rota, while de er are fully protected on Saipan, however, considerable illegal hunting occ urs on each island. Deer are not legally protected on Pohnpei. C. mariannus consumes a variety of native and introduced plants, including cultivated s pecies. Damage to native ecosystems or crops has been reported on Guam, Rot a, and Pohnpei during periods of high deer abundance. Browsing damage to na tive forests can be extensive, causing significant changes in forest struct ure and species composition. The objectives of current deer management prog rams in the Marianas are not compatible with the conservation of native eco systems and recovery of endangered species. Recommendations are made to red uce deer densities dramatically through intensive continuous harvest over l arge areas of each island and to eradicate deer from sites of significant e cological value.