Understanding landscape and plot-scale habitat utilisation by Malayan sun bear (Helarctos malayanus) in degraded lowland forest

Abstract

Abstract Malayan sun bear (Helarctos malayanus) is a forest-dependent species globally threatened by loss of suitable habitat and hunting. Understanding how sun bears utilise habitat in more degraded landscapes is increasingly important for the effective conservation of the species. We studied how landscape and plot attributes affect sun bear habitat use along a gradient of logging disturbance in a lowland forest site of Sumatra. We conducted surveys of bear claw marks to indicate sun bear habitat use at plot and landscape scales, and inform forest restoration strategies that benefit the conservation management of the species. We recorded 12 habitat features and the presence/absence of claw marks in 262 plots in four different habitat types. We reduced the number of habitat variables using Principal Components Analysis (PCA), resulting in four derived habitat factors. We used these factors in a Discriminant Analysis to refine habitat classifications of plots, and modelled presence/absence of claw marks using the PCA factors in a binary logistic regression. We inventoried tree species in a subset of randomly selected plots with claw marks alongside paired control plots with no claw marks. We compared tree community compositions in these plots using ANOSIM and SIMPER analyses. Based on claw mark signs, sun bear habitat use appeared to be non-random and was significantly associated with gradients of increasing habitat intactness, from non-forest habitat to least disturbed forest. Two PCA factors explained the probability of bears utilising a given habitat, which increased with tree biomass and decreased with understorey cover. At the plot level, tree family and species compositions were significantly different between plots without and with claw marks. The abundance and use of Olacaceae stems was significantly higher in plots with claw marks. Incorporating forest restoration strategies that enhance or increase more intact forest and the availability of key tree resources should benefit the conservation of sun bears and encourage natural forest regeneration in these degraded landscapes. We also emphasise the conservation value of degraded forest habitats for this species while ensuring bear movement and connectivity within modified landscape matrices.