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

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).

First integrative trend analysis for a great ape species in Borneo.

For many threatened species the rate and drivers of population decline are difficult to assess accurately: species' surveys are typically restricted to small geographic areas, are conducted over short time periods, and employ a wide range of survey protocols. We addressed methodological challenges for assessing change in the abundance of an endangered species. We applied novel methods for integrating field and interview survey data for the critically endangered Bornean orangutan (Pongo pygmaeus), allowing a deeper understanding of the species' persistence through time.

Body language: The interplay between positional behavior and gestural signaling in the genus Pan and its implications for language evolution.

Objectives: The gestural repertoires of bonobos and chimpanzees are well documented, but the relationship between gestural signaling and positional behavior (i.e., body postures and locomotion) has yet to be explored.

Population-specific use of the same tool-assisted alarm call between two wild orangutan populations (Pongo pygmaeus wurmbii) indicates functional arbitrariness [corrected].

Arbitrariness is an elementary feature of human language, yet seldom an object of comparative inquiry. While arbitrary signals for the same function are relatively frequent between animal populations across taxa, the same signal with arbitrary functions is rare and it remains unknown whether, in parallel with human speech, it may involve call production in animals. To investigate this question, we examined a particular orangutan alarm call - the kiss-squeak - and two variants - hand and leaf kiss-squeaks.

Considering the role of social dynamics and positional behavior in gestural communication research.

While the hominin fossil record cannot inform us on either the presence or extent of social and cognitive abilities that may have paved the way for the emergence of language, studying non-vocal communication among our closest living relatives, the African apes, may provide valuable information about how language originated. Although much has been learned from gestural signaling in non-human primates, we have not yet established how and why gestural repertoires vary across species, what factors influence this variation, and how knowledge of these differences can contribute to an understanding of gestural signaling's contribution to language evolution. In this paper, we review arguments surrounding the theory that language evolved from gestural signaling and suggest some important factors to consider when conducting comparative studies of gestural communication among African apes.

Understanding the impacts of land-use policies on a threatened species: is there a future for the Bornean orang-utan?

The geographic distribution of Bornean orang-utans and its overlap with existing land-use categories (protected areas, logging and plantation concessions) is a necessary foundation to prioritize conservation planning. Based on an extensive orang-utan survey dataset and a number of environmental variables, we modelled an orang-utan distribution map. The modelled orang-utan distribution map covers 155,106 km(2) (21% of Borneo's landmass) and reveals four distinct distribution areas.