Habitat Characteristics and Their Effects on the Density of Groups of Western Hoolock Gibbon (Hoolock hoolock) in Namdapha National Park, Arunachal Pradesh, India

Ray, P. C.; Kumar, Awadhesh; Devi, Ashalata; Krishna, Murali C.; Khan, M. L.; Brockelman, Warren Y.

doi:10.1007/s10764-015-9834-4

Cited by 13 publications

(15 citation statements)

References 23 publications

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“…An estimate of a listening area with a radius of 1 km is a standard often assumed in the literature (e.g., Brockelman et al, 2009;Gilhooly et al, 2015;Ray et al, 2015;Traeholt et al, 2005). We also wished to test density within a smaller radius that better reflected our ability to detect groups reliably, so we selected 0.6 km.…”

Section: Discussionmentioning

confidence: 99%

“…After mapping the groups, circles of radii equal to 0.6 and 1 km were drawn around each LP, and the numbers of groups within these circular areas were counted (overlap areas were counted only once). An estimate of a listening area with a radius of 1 km is a standard often assumed in the literature (e.g., Brockelman et al, 2009; Gilhooly et al, 2015; Ray et al, 2015; Traeholt et al, 2005). We also wished to test density within a smaller radius that better reflected our ability to detect groups reliably, so we selected 0.6 km.…”

Section: Methodsmentioning

confidence: 99%

“…All of the 20 recognized species of gibbons give loud songs and in all but two, male and female components are organized into rather stereotyped duets which signal the presence of breeding groups in fixed territories. At the end of a day of listening, compass directions and times of calls from different LPs are used to map the locations of groups through “triangulation,” and population density is estimated by dividing the number of mapped groups by the “listening area,” the area within which all groups can be heard (e.g., Brockelman & Srikosamatara, 1993; Brockelman et al, 2009; Buckley et al, 2006; Cheyne et al, 2008; Estrada et al, 2004; Hamard et al, 2010; Nijman & Menken, 2005; Nongkaew et al, 2017; O'Brien et al, 2004; Phoonjampa & Brockelman, 2008; Rawson et al, 2009; Ray et al, 2015; Traeholt et al, 2005; Yanuar et al, 2019). Because gibbons do not duet every day, it is necessary to estimate a density correction factor consisting of the probability of a group singing per day, or over a period of days (i.e., its “availability” for detection) to prevent underestimation of density.…”

Section: Introductionmentioning

confidence: 99%

“…The purpose of this study is to compare the point transect Distance method against a traditional method of acoustic survey (Brockelman et al, 2009; Phoonjampa & Brockelman, 2007; Ray et al, 2015) in a survey of the eastern hoolock gibbon ( Hoolock leuconedys ) in the Htamanthi Wildlife Sanctuary (WS), Myanmar. We will then make suggestions for the use of the point transect Distance method in fixed‐point acoustic surveys of gibbons.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of point transect distance and traditional acoustic point‐count sampling of hoolock gibbons in Htamanthi Wildlife Sanctuary, Myanmar

Brockelman

Tun

et al. 2020

American J Primatol

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Effective conservation demands more accurate and reliable methods of survey and monitoring of populations. Surveys of gibbon populations have relied mostly on mapping of groups in "listening areas" using acoustical point-count data. Traditional methods of estimating density in have usually used counts of gibbon groups within fixed-radius areas or areas bounded by terrain barriers to sound transmission, and have not accounted for possible decline in detectability with distance. In this study we sampled the eastern hoolock gibbon (Hoolock leucogenys) population in Htamanthi Wildlife Sanctuary (WS), Myanmar, using two methods: the traditional pointcount method with fixed-radius listening areas, and a newer method using pointtransect Distance analysis from a sample point established in the center of each listening point array. The basic data were obtained by triangulating on singing groups from four LPs for 4 days, in 10 randomly selected sample areas within the sanctuary. The point transect method gave an average density of 3.13 groups km −2 , higher than the estimates of group density within fixed-radius areas without correction for detectability. A new method of analysis of singing probability per day (p[1]) gave an estimate of 0.547. Htamanthi WS is an important conservation area containing an estimated 7000 (95% confidence interval: 5000-10,000) hoolock groups. Surveys at Htamanthi WS and locations in the Hukaung Valley suggest that the extensive evergreen forests in northern Myanmar have the capacity to support 2-4 (average about 3) groups of hoolock gibbons per km 2 , but most forests in its range have yet to be surveyed.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison of point transect distance and traditional acoustic point‐count sampling of hoolock gibbons in Htamanthi Wildlife Sanctuary, Myanmar

Brockelman

Tun

et al. 2020

American J Primatol

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“…Across its distribution, Western hoolock gibbon experiences fragmented habitats in Cachar district of Assam, India. It is very important to understand the fundamental link between this species and its habitat for formulation of effective conservation plans (Das et al, 2005, Ray et al, 2015. The habitat of Western hoolock gibbons in Cachar district includes forest patches inside tea estates, village woodlots near forest fringes and small tree cladded areas which are in contrast to the reported habitats of Western hoolock gibbons in other parts of India that are tropical and subtropical evergreen, tropical wet evergreen, tropical semi-evergreen, tropical moist deciduous, and sub-tropical hill forests (Kumar et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Distribution of Western Hoolock Gibbons and Nutritional Status of Food Plants in Cachar District of Assam, India: Reaching Out to Local Communities for Conservation

Deb¹,

Roychoudhury²,

Bhattacharjee³

et al. 2019

Acta Univ. Agric. Silvic. Mendelianae Brun.

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Western hoolock gibbon (Hoolock hoolock) is listed as an endangered mammal in IUCN Red List. It is also listed in CITES Appendix I and in the Schedule I of the Indian Wildlife (Protection) Act, 1972. In the present work the status and distribution of Western hoolock gibbons in Cachar district of Assam, India was explored by conducting field studies from September 2012 to August 2013 using line transect and call count methods. Group composition, group size and adult sex ratio of nine gibbon groups and one solitary male were recorded. Groups comprised 36 % adult males, 32 % adult females, 10 % sub‑adult males, 11 % juveniles and 11 % infants and the encounter rate was 0.17. Group size ranged from 2 to 5 and mean group size was 2.8 ± 1.1. Nutritional status of food plants consumed by Western hoolock gibbons were analyzed and chemical composition was determined. Proximate analysis revealed that the mean value of crude protein (9.73 ± 0.4), crude fibre (16.1 ± 0.6), ether extract (1.07 ± 0.06), NFE (66.24 ± 0.43) and ash (7.03 ± 0.27) in plant samples. A moderate positive correlation was noted between higher protein content and higher crude fibre content in food plants (r = 0.48), which is likely to influence food selection and feeding pattern. Timber felling, fuel‑wood collection, agriculture and expansion of tea estates were identified as major threats to conservation of Western hoolock gibbons. The present study recommends taking up awareness programmes and formulation of policy interventions involving the local communities to arrive at a participatory biodiversity conservation plan at local levels particularly involving the village councils (gram panchayats).

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A distance sampling approach to estimate density and abundance of gibbon groups

Tran

Nguyen

et al. 2018

American J Primatol

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All 18 species of gibbons are considered threatened with extinction and listed on the IUCN Red List of Threatened Species. Because gibbons (Hylobatidae) are one of the most threatened primate families, a great need exists to determine and monitor their status effectively. To meet this need, we employed distance sampling methods to estimate the density and number of gibbon groups. We focused on southern yellow-cheeked crested gibbon in the Nam Cat Tien sector of Cat Tien National Park, Vietnam, from July to October, 2016. We used an auditory point count method at 48 listening posts to detect gibbon groups. We estimated our detection probability of calling groups of gibbons within 1,200 m of a listening post was 0.63 (95% CI: 0.54-0.74). In addition, we estimated the daily calling probability of a gibbon group to be 0.46 (95% CI: 0.33-0.59) and interpreted this as the probability that a group was available to be detected. We adjusted our group density and abundance estimates by both detection and availability probabilities. Ultimately we estimated 325 (95% CI: 232-455) gibbon groups in the Nam Cat Tien sector. Our results suggest that Cat Tien National Park contains one of the largest populations of southern yellow-cheeked crested gibbon in Vietnam. Our methods are one way of avoiding underestimation of gibbon group density and abundance by incorporating uncertainty in gibbon group availability and detection.

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Habitat Characteristics and Their Effects on the Density of Groups of Western Hoolock Gibbon (Hoolock hoolock) in Namdapha National Park, Arunachal Pradesh, India

Cited by 13 publications

References 23 publications

Comparison of point transect distance and traditional acoustic point‐count sampling of hoolock gibbons in Htamanthi Wildlife Sanctuary, Myanmar

Comparison of point transect distance and traditional acoustic point‐count sampling of hoolock gibbons in Htamanthi Wildlife Sanctuary, Myanmar

Distribution of Western Hoolock Gibbons and Nutritional Status of Food Plants in Cachar District of Assam, India: Reaching Out to Local Communities for Conservation

A distance sampling approach to estimate density and abundance of gibbon groups

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