Global Demand for Natural Resources Eliminated More Than 100,000 Bornean Orangutans

Abstract

Unsustainable exploitation of natural resources is increasingly affecting the highly biodiverse tropics [1, 2]. Although rapid developments in remote sensing technology have permitted more precise estimates of land-cover change over large spatial scales [3-5], our knowledge about the effects of these changes on wildlife is much more sparse [6, 7]. Here we use field survey data, predictive density distribution modeling, and remote sensing to investigate the impact of resource use and land-use changes on the density distribution of Bornean orangutans (Pongo pygmaeus). Our models indicate that between 1999 and 2015, half of the orangutan population was affected by logging, deforestation, or industrialized plantations. Although land clearance caused the most dramatic rates of decline, it accounted for only a small proportion of the total loss. A much larger number of orangutans were lost in selectively logged and primary forests, where rates of decline were less precipitous, but where far more orangutans are found. This suggests that further drivers, independent of land-use change, contribute to orangutan loss. This finding is consistent with studies reporting hunting as a major cause in orangutan decline [8-10]. Our predictions of orangutan abundance loss across Borneo suggest that the population decreased by more than 100,000 individuals, corroborating recent estimates of decline [11]. Practical solutions to prevent future orangutan decline can only be realized by addressing its complex causes in a holistic manner across political and societal sectors, such as in land-use planning, resource exploitation, infrastructure development, and education, and by increasing long-term sustainability [12]. VIDEO ABSTRACT.

Advancing conservation planning for western chimpanzees using IUCN SSC A.P.E.S.—the case of a taxon-specific database

“…We followed a commonly used procedure to predict ape density distributions (Murai et al 2013, Voigt et al 2018. Specifically, we first fitted a full model to establish the relationship between chimpanzee densities and several social-ecological predictor variables, and then predicted chimpanzee density distribution based on multi-model inference (Burnham and Anderson 2002).…”

Conservation and the social sciences: Beyond critique and co‐optation. A case study from orangutan conservation

“…There is virtually nothing known about the proportions and sizes of the various land cover types in relation to orangutan survival (but see Voigt et al, ). Orangutans, at least on Borneo, also appear to be more terrestrial than previously thought (Ancrenaz et al, ), but they may avoid going to the ground when people are near because of increased risks of being detected and killed (Spehar et al, ).…”

“…Recent population trend studies indicate that killing—whether through hunting, poaching or conflict—is one of the key drivers of orangutan extinction on Borneo, with the largest absolute declines noted for areas where no or limited deforestation is taking place (Santika et al, ; Voigt et al, ). These insights are not yet widely accepted in the orangutan conservation community (Sherman et al, ).…”

Trade, transboundary impacts and the implementation of SDG 12

“…Partly driven by demand for biodiesel, which ostensibly fulfils climate change mitigation goals, in Indonesia and Malaysia, forest is being cleared both legally and illegally to sell timber and make way for agricultural land for palm oil plantations. This has greatly reduced numbers of orangutan and other species (Voight et al 2018). The draining of peat bogs to make way for palm oil, and the burning of virgin forest, has also led to vast amounts of trapped methane and carbon emissions being released into the environment.…”