Distribution and abundance of Peleng Tarsier (Tarsius pelengensis) in Banggai Island group, Indonesia.

The Peleng tarsier (Tarsius pelengensis) is poorly known primate, with a range limited to Banggai island-group, Central Sulawesi, Indonesia. It was classified as "Endangered" by IUCN in 2017 based on extremely limited demographic and distributional data. The aim of this study was to collect and analyze data on the population and distribution of Peleng tarsiers. Surveys were conducted over approximately 5 months in 2017 and 2018 across Peleng and the neighboring islands of Banggai, Labobo, and Bangkurung. We determined that tarsiers only occur on Peleng and Banggai Island. The average population density in Peleng and Banggai was estimated to be 234 individuals/km2. This is comparable to the broad ranges of tarsier densities throughout Sulawesi and offshore islands. Peleng tarsiers were found in all elevations (0-937 m above sea level) and nearly all vegetated habitats in Peleng island. Using the IUCN criteria for determining conservation status, in conjunction with our new data, we believe that the Peleng tarsier population should be classified as "Vulnerable".

The accuracy of volunteer surveyors for obtaining tree measurements in tropical forests.

Volunteer-led surveys are increasingly used to collect ecological information and may represent a means for obtaining the tree measurement datasets necessary to calculate carbon stocks in tropical forests in order to justify funding like REDD+. However, the accuracy of tree measurements collected by volunteers remains unassessed. Here, we examine how tree measurements collected by student volunteers vary compared to measurements collected by trained ecologists using identical methods. Measurements by both teams were collected at 11 habitat plots on Buton Island, Indonesia. Both teams counted similar numbers of trees per plot and obtained positively correlated circumference-at-breast-height measurement values at plot and individual tree scales of aggregation. Volunteer and ecologist-generated median carbon stock estimates differed by just 1.1%. We therefore suggest that with sufficient training and supervision volunteers can be used to obtain accurate tree measurement data for carbon stock calculations.

Synchronous diversification of Sulawesi's iconic artiodactyls driven by recent geological events.

The high degree of endemism on Sulawesi has previously been suggested to have vicariant origins, dating back to 40 Ma. Recent studies, however, suggest that much of Sulawesi's fauna assembled over the last 15 Myr. Here, we test the hypothesis that more recent uplift of previously submerged portions of land on Sulawesi promoted diversification and that much of its faunal assemblage is much younger than the island itself. To do so, we combined palaeogeographical reconstructions with genetic and morphometric datasets derived from Sulawesi's three largest mammals: the babirusa, anoa and Sulawesi warty pig. Our results indicate that although these species most likely colonized the area that is now Sulawesi at different times (14 Ma to 2-3 Ma), they experienced an almost synchronous expansion from the central part of the island. Geological reconstructions indicate that this area was above sea level for most of the last 4 Myr, unlike most parts of the island. We conclude that emergence of land on Sulawesi (approx. 1-2 Myr) may have allowed species to expand synchronously. Altogether, our results indicate that the establishment of the highly endemic faunal assemblage on Sulawesi was driven by geological events over the last few million years.