Impact of Typhoon Haiyan on a Philippine Tarsier Population.

Over the last 2 decades the Philippine tarsier (Carlito syrichta aka Tarsius syrichta) has had its conservation status revised from Endangered to Data Deficient to Near Threatened. The last status change was based on a study of the species' population density, which suggested that a single natural catastrophe could potentially wipe out the Philippine tarsier. In 2013 typhoon Haiyan hit Bohol, one of the island strongholds for this species. In this study we compare the density of the Bohol tarsier population within the Philippine Tarsier and Wildlife Sanctuary before and after the typhoon. We demonstrate that the typhoon significantly affected the density of the Philippine tarsier in the sanctuary. Before the typhoon, tarsier density was approximately 157 individuals/km2 whereas after the typhoon the density was a mere 36 individuals/km2. Prior to the typhoon, more Philippine tarsiers were found in older secondary forest than in younger secondary forest, whereas after the typhoon all observed individuals were found in relatively younger secondary forest. Vegetation plots where we observed Philippine tarsiers prior to the typhoon contained a mean of 33 trees/m2, with a mean diameter at breast height (DBH) of 24 cm, and a mean height of 4 m. After the typhoon vegetation plots contained an average of 156 trees, had a mean DBH of 6 cm, and a mean height of 2 m. Based on the IUCN Red List criteria, the reduction and fluctuation in the density of this species suggests that the conservation status of the Philippine tarsier should be changed to Vulnerable. This study indicates natural disasters can have a significant effect on the extinction risk of primates, with implications for future effects of anthropogenic climate change.