Sustainable forest management is vital for the persistence of sun bear Helarctos malayanus populations in Sabah, Malaysian Borneo

Abstract

Abstract With large mammals in Southeast Asia facing a host of threats such as forest loss and poaching, one important strategy in supporting conservation interventions is to understand local trends in species distributions. In Sabah, Malaysian Borneo, selective logging has both historically (conventional selective logging) and currently (reduced impact logging) impacted large areas of forest. Furthermore, the impact of poaching remains difficult to assess, potentially leading forest managers to underestimate its effects on large mammals. Our study focused on the sun bear (Helarctos malayanus), a forest dependent species threatened by poaching across its range. We used camera trap data collected in 2014 and 2018 from 127 camera trap stations in two adjacent forest blocks in Sabah. One of these blocks is a complex of degraded protected areas (formerly logged using conventional selective logging), interspersed with two areas of forest plantations (Tangkulap), while the other block is an active production forest logged using reduced impact logging techniques (Deramakot). We ran single-season occupancy models using covariates representing both habitat quality and poaching pressure to understand what factors most influenced sun bear habitat use and projected their distribution over the study area. We found that sun bear habitat selection was most strongly influenced by a dynamic covariate representing habitat quality, Normalised Difference Moisture Index (NDMI) from Landsat satellite data. Sun bear occupancy marginally increased from 2014 to 2018, in response to forest regeneration in Deramakot and Tangkulap. Overall, sun bear distribution was higher in the reduced impact logged and sustainably managed Deramakot compared to Tangkulap. Our proxies for poaching pressure had very minor effects on sun bear occupancy, suggesting that the population in this study area may not be subject to intense poaching. We highlight that sun bear populations can in fact better persist in well-managed production forests as compared to degraded protected areas.