The power of gibbon songs: Going beyond the research to inform conservation actions.

Gibbons (Hylobatidae) are the smallest of the apes, known for their arboreal behavior and stereotyped songs. These species and sex-specific songs are often the subject of detailed studies regarding their evolution, responses to changing environments, involvement in social behavior, and used to design vocalization-based survey techniques to monitor population densities and trends. What is poorly understood is the value and impact of using the science and sound of gibbon vocalization and gibbon stories in education and outreach to complement nongovernmental organizations (NGOs) efforts. We present an example of how Borneo Nature Foundation, a NGOs based in Indonesia, is working to use the recordings of the songs of Bornean white-bearded gibbons (Hylobates albibarbis) to inform conservation actions and education efforts. Gibbons in Indonesia are often poorly known or understood by the public compared to orangutans (Pongo spp). We showcase how a field of study, namely primate acoustics, is an untapped resource to create digital content to engage with local, national and international communities and can be developed into educational tools in the form of storytelling, mobile apps and games, to highlight the plight of these threatened species and how to conserve them.

Home range variation and site fidelity of Bornean southern gibbons [Hylobates albibarbis] from 2010-2018.

Gibbons are highly territorial and have two key areas within these territories. The core area in which we find all sleeping trees and the trees from which the gibbons duet and the wider home range (HR) which has varying levels of overlap with neighbouring gibbon groups. The core area is strenously defended, with the wider HR being more of a shared area for neighbouring groups. We present ranging and movement data on four wild gibbon groups from January 2010 to July 2018. Global Positioning System (GPS) data were collected every 5 mins on habitauted groups in Sebangau, Central Kalimantan, Indonesia resulting in 35,521 waypoints. Gibbon home- and corerange sizes were calculated using 95%, and 50%, volume contours of kernel density estimates. Home-ranges ranged from 58.74-147.75 ha with a mean of 95.7 ± SD 37.75 ha, the highest of comparable Hylobates species. Core-range size ranged from 20.7-51.31 ha with a mean size of 31.7 ± SD 13.76 ha. Gibbons had consistant site fidelity for their home- and core ranges; percentage overlap ranged from 4.3 23.97% with a mean 16.5 ± SD 8.65% overlap in home-range area. Core ranges did not overlap with the exception of two groups, in which a 0.64 ha (2.69%) overlap occurred. Unsurprisingly forest loss from fire does affect the location of the HR of the impacted group, but does not appear to affect adjacent groups, though more data are needed on this. Understanding the complex use of space of these territorial animals is important in assessing both carrying capacity for wild populations and understading how reintroduced gibbon pairs will establish their core and HR.

A Short Cut to Mushrooms - Red Langur (Presbytis rubicunda) Consumption of Terrestrial Fungus.

We report the first in-depth evidence of targeted mushroom foraging in an Asian colobine. Using direct observations (2010-2018) and camera traps (2008-2018) in the Sebangau Forest, Central Kalimantan, Indonesian Borneo, we show how adult female red langurs (Presbytis rubicunda) are regularly descending to the ground to consume mushrooms. We recorded 82 counts (0.36% of all focal observations, n = 25,502) of the focal adult langur on the ground from direct observations of habituated groups, and 80 independent images/videos of red langurs on the ground were obtained from the camera traps representing 1.12% of total images (n = 7,145). Mushroom consumption took place in 4 families, representing 0.04% of total focal behaviour observations and 24.3% of total time feeding on the ground. From the camera trap photos, red langurs are spending 20% of time on the ground feeding. We speculate that mushrooms could be a supplementary food for adult female langurs as there is an increase in consumption in April and November.