Estimated Density, Population Size and Distribution of the Endangered Western Hoolock Gibbon (Hoolock hoolock) in Forest Remnants in Bangladesh

Abstract

Tropical forests are threatened worldwide due to deforestation. In South and Southeast Asia, gibbons (Hylobatidae) are important to seed dispersal and forest regeneration. Most gibbons are threatened due to deforestation. We studied the western hoolock gibbon (Hoolock hoolock) in Bangladesh to determine population size and extent of suitable habitat. We used distance sampling to estimate density across 22 sites in northeastern and southeastern Bangladesh. We used Maxent modeling to determine areas of highly suitable habitat throughout Bangladesh. Density was estimated to be 0.39 ± 0.09groups/km2, and the total estimated population was 468.96 ± 45.56 individuals in 135.31 ± 2.23 groups. The Maxent model accurately predicted gibbon distribution. Vegetation cover, isothermality, annual precipitation, elevation and mean temperature of the warmest quarter influenced distribution. Two areas in the northeast and two areas in the southeast have high potential for gibbon conservation in Bangladesh. We also found significantly more gibbons in areas that had some level of official protection. Thus, we suggest careful evaluation, comprehensive surveys and restoration of habitats identified as suitable for gibbons. We recommend bringing specific sites in the northeastern and southeastern regions under protection to secure habitat for remaining gibbon populations.

Unveiling the Diverse Mammalian Species of a Tropical Rainforest in Northeast Bangladesh

“…The Western hoolock gibbon and Assamese macaque entirely inhabit the trans-boundary forest areas with less human disturbance whilst the remaining primate fauna were found mostly in the plantation forests across the boundary. Naher et al (2021) reported three groups of Western hoolock gibbon from the PHR whilst the Bengal slow was detected by a recent study (Choudhury et al 2022). The Rhesus macaque was common across the plantation forests, with frequent sightings on south and western regions.…”

Diet, Feeding Habit and Behavioral Activity of Rhesus Macaque (Macaca mulatta) at Charmuguria of Madaripur, Bangladesh

“…At noon, the macaque traveled more to find suitable areas with high food abundance where the group would remain safe until sunset. During the afternoon, group members spent more time for foraging and feeding in preparation to stay healthy for the whole night (Khan, 2020 andAkhter, 2021).…”