Abundance and Distribution of Sympatric Gibbons in a Threatened Sumatran Rain Forest

O’Brien, Timothy G.; Kinnaird, Margaret F.; Nurcahyo, Anton; Iqbal, M. C. M.; Rusmanto, Mohamed

doi:10.1023/b:ijop.0000019152.83883.1c

Cited by 97 publications

(63 citation statements)

References 24 publications

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“…Wildfires and logging were found to negatively affect the abundance of orangutans (Felton et al 2003) and to result in lower densities of gibbons, principally due to a decrease in food availability (Johns 1987, 1988, Johns & Skorupa 1987, O'Brien et al 2003a, 2004). However, gibbons were able to persist in disturbed forests due to their dietary flexibility (Harrison et al 2005, Cheyne 2010), but their reproductive potential was lowered by the shift towards folivory (O'Brien et al 2004). Furthermore, the density of H. albibarbis was negatively correlated with elevation in Gunung Palung National Park, West Kalimantan, corresponding to fewer large trees and a lower availability of gibbon food items at higher altitude (Marshall & Leighton 2006, Marshall 2009).…”

Section: Populations and Densitymentioning

confidence: 99%

“…Furthermore, primates have been found to be less abundant near forest edges (Lehman et al 2003). Studies have suggested that gibbons, small apes native to Southeast Asia, are able to persist in disturbed forests thanks to their dietary flexibility (Harrison et al 2005, Cheyne 2010), but that their reproductive potential is lowered by this shift towards folivory (O'Brien et al 2004). The density of the southern Bornean white-bearded gibbon Hylobates albibarbis was found to be negatively correlated with elevation in the Gunung Palung National Park, West Kalimantan, Indonesia, which co incided with fewer large trees and lower availability of gibbon food items (Marshall & Leighton 2006, Marshall 2009.…”

Section: Introductionmentioning

confidence: 99%

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Population mapping of gibbons in Kalimantan, Indonesia: correlates of gibbon density and vegetation across the species’ range

Cheyne¹,

Gilhooly²,

Hamard³

et al. 2016

Endang. Species. Res.

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Section: Populations and Densitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Population mapping of gibbons in Kalimantan, Indonesia: correlates of gibbon density and vegetation across the species’ range

Cheyne¹,

Gilhooly²,

Hamard³

et al. 2016

Endang. Species. Res.

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“…O'Brien et al (2004) found that the probability of agile gibbons calling stabilises by day 4. Thus, each listening post was surveyed for a period of four consecutive days during this study, with the exception of the second sample period, which was surveyed from the 6-7 July and 9-10 July.…”

Section: Frequency Of Callingmentioning

confidence: 98%

“…Although gibbons have formed the focus of many behavioural and ecological studies, limited data are available in terms of their population and demographic trends (Mitani 1990;O'Brien et al 2003O'Brien et al , 2004, due to low visibility and unreliable behaviour upon detection (Brockelman and Srikosamatara 1993;Nijman 2004).…”

Section: Introductionmentioning

confidence: 99%

“…Gittins and Raemaekers 1980;Leighton 1987;Mitani 1990;McConkey et al 2003). Gibbons utter characteristic calls most mornings, which can be heard over a distance of up to 2 km in some terrain (Gittins and Raemaekers 1980;Reichard and Sommer 1997;O'Brien et al 2004), although audibility of calls does not generally exceed 1 km through level forest (Brockelman and Ali 1987).…”

Section: Introductionmentioning

confidence: 99%

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Survey of Hylobates agilis albibarbis in a logged peat-swamp forest: Sabangau catchment, Central Kalimantan

2006

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Few data are available on gibbon populations in peat-swamp forest. In order to assess the importance of this habitat for gibbon conservation, a population of Hylobates agilis albibarbis was surveyed in the Sabangau peat-swamp forest, Central Kalimantan, Indonesia. This is an area of about 5,500 km(2) of selectively logged peat-swamp forest, which was formally gazetted as a national park during 2005. The study was conducted during June and July 2004 using auditory sampling methods. Five sample areas were selected and each was surveyed for four consecutive days by three teams of researchers at designated listening posts. Researchers recorded compass bearings of, and estimated distances to, singing groups. Nineteen groups were located. Population density is estimated to be 2.16 (+/-0.46) groups/km(2). Sightings occurring either at the listening posts or that were obtained by tracking in on calling groups yielded a mean group size of 3.4 individuals, hence individual gibbon density is estimated to be 7.4 (+/-1.59) individuals/km(2). The density estimates fall at the mid-range of those calculated for other gibbon populations, thus suggesting that peat-swamp forest is an important habitat for gibbon conservation in Borneo. A tentative extrapolation of results suggests a potential gibbon population size of 19,000 individuals within the mixed-swamp forest habitat sub-type in the Sabangau. This represents one of the largest remaining continuous populations of Bornean agile gibbons. The designation of the Sabangau forest as a national park will hopefully address the problem of illegal logging and hunting in the region. Further studies should note any difference in gibbon density post protection.

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Flowers Are an important food for small apes in southern Sumatra

Lappan¹

2009

American J Primatol

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Flowers are included in the diets of many primates, but are not generally regarded as making an important contribution to primate energy budgets. However, observations of a number of lemur, platyrrhine, and cercopithecine populations suggest that some flower species may function as key primate fallback foods in periods of low abundance of preferred foods (generally ripe fruits), and that flowers may be preferred foods in some cases. I report heavy reliance on flowers during some study months for a siamang (Symphalangus syndactylus) population in southern Sumatra. Siamangs at Way Canguk spent 12% of feeding time eating flowers from October 2000 to August 2002, and in 1 month flower-feeding time exceeded 40% of total feeding time. The overall availabilities of fig and nonfig fruits, flowers, and new leaves in the study area were not significant predictors of the proportion of time that siamangs spent consuming any plant part. However, flower-feeding time was highest in months when nonfig fruit-feeding time was lowest, and a switch from heavy reliance on fruit to substantial flower consumption was associated with a shift in activity patterns toward reduced energy expenditure, which is consistent with the interpretation that flowers may function as a fallback food for Way Canguk siamangs. Hydnocarpus gracilis, a plant from which siamangs only consume flowers, was the third-most-commonly consumed plant at Way Canguk (after Ficus spp. and Dracontomelon dao), and flowers from this plant were available in most months. It is possible that relatively high local availability of these important siamang plant foods is one factor promoting high siamang density in the study area.

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Abundance and Distribution of Sympatric Gibbons in a Threatened Sumatran Rain Forest

Cited by 97 publications

References 24 publications

Population mapping of gibbons in Kalimantan, Indonesia: correlates of gibbon density and vegetation across the species’ range

Population mapping of gibbons in Kalimantan, Indonesia: correlates of gibbon density and vegetation across the species’ range

Survey of Hylobates agilis albibarbis in a logged peat-swamp forest: Sabangau catchment, Central Kalimantan

Flowers Are an important food for small apes in southern Sumatra

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