Insights from 20 years of mammal population research in Indonesia

Mammal populations are declining in biodiverse tropical regions. Global analyses identify Indonesia as a hotspot of vertebrate decline, although relatively few data are available to substantiate these claims. We reviewed research articles from 2000 to 2020 on Indonesia’s 104 medium to large terrestrial mammal species to help inform conservation management and future research. We found 308 peer-reviewed studies published in English or Bahasa Indonesia, with an increase in publications over the years. Studies of species distributions dominated the literature, followed by publications on abundance, species diversity, and combinations of these topics. Most publications concerned single species conducted at a single location and time point. We identify four key knowledge gaps for future research and conservation efforts: 1) a disproportionate focus on a small number of species; 2) geographic bias to west Indonesia (Sumatra, Kalimantan, and Java-Bali) with few published studies from central (Sulawesi, Nusa Tenggara, and Maluku) and east (Papua) of the country; 3) limitations to survey design, sampling effort, and data analysis; and, 4) lack of long-term species population studies. We also noted challenges for local researchers to publish their studies in international journals due to language barriers and cost. Greater use of existing biodiversity data and continued capacity building of local researchers, particularly those in central and east Indonesia, are critical to effectively guide future wildlife monitoring and improve mammal conservation status.