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

Abstract

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.

Gibbons aren’t singing in the rain: presence and amount of rainfall influences ape calling behavior in Sabah, Malaysia

“…Animals are known to exhibit distinct personality traits, or behavioral syndromes, where certain individuals are more bold or aggressive than others 52,53 , and it seems likely that certain gibbon individuals or pairs call more often than others, which would also lead to spatial variation in gibbon calling events. Previous reports of home range size of two gibbon pairs in our population were about 0.34 km 2,54 , but home range size can vary widely even within the same population 55 , making it difficult to know precisely how many pairs were included in the present study. Based on conservative estimates of gibbon home range size (0.3-0.5 km 2 ) it seems likely that at least 6-10 pairs were recorded in our 3 km 2 study area.…”

“…For example, early field trials indicated that the maximum gibbon recording distance on our recorders and in this environment was 350-400 m, but calls detected at >400 meters were of very low-quality (<10 SNR) and difficult to distinguish using aural and visual means, which means that there was a low possibility of recording the same calls on multiple recorders. Home range size for two gibbon groups in our population was previously estimated to be 34 ha (0.34 km 2 ), but home range size in gibbons has been shown to be highly variable even within populations 55 , so this may not be representative of the gibbons included in our study. But, given the high degree of territoriality in gibbons 16 , and their relatively small home range size relative to grid spacing of the autonomous recorders, the possibility of re-recording the same vocalizing pair on different recorders in the present study was minimal.…”

Brevity is not a universal in animal communication: evidence for compression depends on the unit of analysis in small ape vocalizations

“…Early field tests indicate that detection distance of calling gibbons is approximately 400 m[75] using our recording settings. We considered high-quality recordings taken from each recorder as a different male based on the territorial nature of gibbons, the documented territory size in other gibbon species[76][77][78] and estimated detection distance of our recorders[75]; see Clink et al[72] for more details.…”

Long‐term effects of forest fire on habitat use by siamangs in Southern Sumatra

“…Habitat loss or degradation may leave survivors with smaller HR, lower-quality HR, or both. In the only other study of gibbons in fire-affected habitat, HR locations for three neighboring groups of Bornean southern gibbons (H. albibarbis) remained stable before and three years after a fire, although habitat within one HR was damaged and was no longer used (Cheyne et al, 2019). Similarly, 2000Similarly, -2002Similarly, , 2007Similarly, -2009Similarly, , and 2014, and for this project in 2014-2015 (Table 1).…”