Table Of ContentJournal ofthe Bombay Natural HistorySociety, 105(1), Jan-Apr2008 19-23
POPULATION STATUS AND CONSERVATION OF HOOLOCK GIBBONS
HYLOBATESHOOLOCKHARLAN 1834 IN BANGLADESH1
M. Anwarul Islam2 Mostafa M. Feeroz3 Sabir Bin Muzaffar4 Mofizul Kabir3 Sajeda Begum3
, , , , ,
K. Hasan3 Shahriar Mahmud2and Suprio Chakma2
,
'AcceptedSeptember2006
’DepartmentofZoology,UniversityofDhaka, Dhaka 1000, Bangladesh.
’DepartmentofZoology,JahangirnagarUniversity,Savar,Dhaka 1342, Bangladesh.
4SchoolofEnvironmentalScienceandManagement,IndependentUniversity,Bangladesh.
Presentaddress: DepartmentofBiology,CollegeofSciences,UnitedArabEmiratesUniversity, P.O. Box 1755,A1Ain,
UnitedArabEmirates.Email: [email protected]
HoolockGibbon (Hylobateshoolock Harlan 1834) is the only ape thatoccursinthe Indian subcontinent.The species
isclassifiedasendangeredandtheirnumbershavedeclinedthroughouttheirgeographicrangeprimarilyduetohabitat
destruction. We determined the current status of the Hoolock Gibbons in Bangladesh. A total of 35 sites
(10in the north-easternregion and 25 in the south-easternregion) were surveyed forHoolock Gibbonsfrom 2002 to
2005.Atotalof282HoolockGibbonsin96groupswasestimatedtolivein24ofthe35sitesvisited. Severalsiteshave
lost all theirHoolockGibbons within the last 15 years. Kamafuli (partofKaptai National Park) in the south-eastand
LawacharaNationalParkinthenorth-eastwererecognisedastwomajorstrongholdsofHoolockGibbons.Conservation
ofthe remaining Hoolock Gibbons ofBangladesh restson the future management oftheir patchy forest habitats. We
recommendthecessationofillegaldeforestation,habitatrestorationandtranslocationofindividualstomaintain these
last Hoolock Gibbon populations in Bangladesh.
Key words: Hoolock Gibbon, Hylobates hoolock status, conservation, Bangladesh
,
INTRODUCTION
are concomitant with the ongoing deforestation throughout
the country’s forested areas (Gain 2002). Hoolock Gibbons
Gibbonsaresociallymonogamoussmall apesthathold are apparently holding on tenaciously to some last extant
a very important position in the ecology oftropical forests forests in Bangladesh. Currently, the species are globally
(Preuschoftetal. 1984;Chivers2001).Theyhavebeenunder endangered (IUCN 2004) and in Bangladesh, they are
considerable threat primarily due to habitat destruction classified asCriticallyEndangered (IUCN 2000).
throughout their range. Among the 13 gibbon species, Assessing the numberofHoolock Gibbons is a key to
Hoolock Gibbons Hylobateshoolock are the only ones that the understanding of their status and for developing a
occur within the Indian subcontinent and are perhaps under conservation plan to prevent extinction of the species.
the greatest threat throughout their geographic range Generally, assessing primate populations is a difficult task
(Mootnick et al. 1987; MacKinnon and MacKinnon 1987; thatinvariablyleadstoinaccurateestimates(RossandReeve
IslamandFeeroz 1992;Feeroz 1999,2001;Choudhury2001). 2003; Nijman 2004). This is particularly true for gibbon
Habitatdestructionistheprincipalcauseofpopulationdecline species, due to the fact that they use the forest canopy for
(Gittins and Akonda 1982; Gittins 1984; Gittins and Tilson movementandforaging(O'Brienetal. 2004).Theobjective
1984; Chivers 2001; Islametal. 2004).They are distributed ofthisstudywastodeterminethepopulationstatusofHoolock
in various north-eastern states in India, with a current total Gibbons, in all theremaining habitats.
populationofmorethan2,600individuals(Molurcfa/.2005).
Their distribution in southern China and Myanmar is STUDY AREA
recognised, but population estimates are from the 1980s
(Mootnick et al. 1987; MacKinnon and MacKinnon 1987). The present study was conducted in all the known
In Bangladesh, HoolockGibbonpopulationswereestimated Hoolock Gibbon habitats in Bangladesh, along with some
tobe around3,000individuals inthe mid 1980s (Gittinsand habitats previously not surveyed. Thirty-five sites were
Akonda 1982). This number had subsequently crashed to surveyed(Fig. 1).Thenorth-easternandsouth-easternregions
about 200individualsin the 1990s (Feerozand Islam 1992). ofBangladeshconsistofsemi-deciduousandmoistevergreen
The decliningtrendcontinued in many areasofBangladesh, forest patches with a wide variety of tree species (Rashid
withsomeareashavinglostallofitsHoolockGibbons(Feeroz 1991; Ahsan 2001). Each region has its distinct tree
2001;Dasetal. 2003;Islametal. 2004).Theobserveddecline compositionandforestcanopycharacteristics(Ahsan2001).
POPULATION STATUSAND CONSERVATION OF HOOLOCKGIBBONS IN BANGLADESH
5-10 minutes the members of the team would stop to look
aroundforsignsofHoolockGibbonpresence.Thisincluded
hearing of calls; scanning the tree line with binoculars for
HoolockGibbonsinthecanopy;lookingforimportantfruiting
trees (such as species ofArtocarpus and Ficus etc.). When
callswereheard,anattemptwasmadetoassessthedirection
of the call and then to locate the group. Once located, the
age-sex structure of the group was ascertained, with the
assignment of each individual to either adult male, adult
female, subadult male, subadult female, subadult
(undetermined sex), juvenile or infant following Feeroz
(1991) andAhsan (1994). WhencountingHoolockGibbons
in high-density areas (such as Lawachara and Kaptai), extra
time andeffort was given toensure thatdouble counts were
not made by visiting the sites repeatedly and ascertaining
numbers and age-sex structure. The coordinates of the
encounter sites were determined using a hand-held Global
Positioning System (GPS). The GPS coordinates were
recorded into a computer and the locations of the groups
plottedondigitalandpapermapsofthearea.Whenthegroup
could not be located, the group size was conservatively
assumed to be two individuals and the coordinates were
recorded, alongwiththe direction and approximatedistance
from the calling group. The total distance travelled during
walks was estimated from the GPS readings ofthe starting
Fig.1: Hoolock Gibbon survey sites in Bangladesh. Somesites andendingpoints,andfromtheGPScoordinatestakenfrom
arecombined duetotheirclose proximity. variouslocationsduringthecensus walk(includingthoseof
I. Baralekha, 2. Lathitila, Sagarnal, 3. Adampur, Gazipur Tea HoolockGibbon encounters).
Estate, Horinchara, 4. Rema-Kalenga, 5. Lawachara, Chautoli,
6. Satchari, 7. Dighinala, Ramgar, 8. Pablakhali, Kudhukhoza, RESULTS AND DISCUSSION
9. Korerhat, Hazarikhil, 10. Rampahar, Karnafuli,(Kaptai)
II. Dopachari, 12. Chunati, Satghar, 13. Bamu, 14. Thanchi,
15. Alikadam, 16. Sangu, 17. Fashiakhali, Bhomarighona, Two hundred and fifty eight Hoolock Gibbons in
Bangdepa, Bishari, Rajghat, Apar Rezu, 18. Inani, 19. Ukhia, 80 groups were recorded during this survey at all the sites
20.Teknaf.
(Table 1). Additionally, 12 distinctgroupswithanestimated
Tensiteswereidentifiedfromthenorth-easternregion(Fig. 1 24 individualswereheardcalling,makingthetotalpopulation
and Table 1). Most ofthe sites fall under thejurisdiction of to be an estimated 282 individuals in 92 groups.
different forest divisions and have suffered extensive It is clear that Hoolock Gibbon populations have
deforestationoverthelasttwodecades(Gain2002).However, undergonemassivedecline sincethe 1980s,primarilydueto
many of the sites contain habitats that may be regarded as habitatdestruction,althoughtheycontinuetosurviveinsmall
suitable for Hoolock Gibbons (Feeroz 1999, 2001; Islam et pockets of fragmented forests in Bangladesh. The largest
at. 2004, 2006). populationinthenorth-easternregionisinLawacharaNational
Park, within west Bhanugach Reserve Forest (Table 1).
METHODOLOGY Additional populations in Adampur and Baralekha are of
importance, each having larger than or equal to ten
At each site, locals were consulted for identifying individuals, assumed to be required for long-term viability
possiblelocationsofHoolockGibbongroups.Onelocalguide (IUCN 1994; Islam etat. 2006). In recent years, the south-
wastakenandexistingpathswithintheforestpatchorstreams eastern region had been deemed unsuitable for Hoolock
were walked on by a team of 2-4 individuals. The team Gibbons due to acute habitat loss and political unrest (Gain
conducted census walks between 0500 and 1730hours with 2002; Islam et at. 2004). We identified Kamafuli (within
atotaloftwohoursbreakthroughouttheentireperiod.Every KaptaiForestrange),aseriesofhighlyfragmentedsecondary
20 J. Bombay Nat. Hist. Soc., 105 (1), Jan-Apr 2008
POPULATION STATUSAND CONSERVATION OF HOOLOCKGIBBONS IN BANGLADESH
Table1: HoolockGibbon (HG) populations recordedat35sitesduring2002-2005(basedonobservedgroupsandcallinggroups)
Sites Daysof Groups Individuals Groups Numbers Estimated Estimated
counting counted counted calling calling3 groups6 numbers0
North-east(10sites)
Baralekha 9 3 10 3 10
Lathitila 2 1 5 2 4 5 9
Shagamal 2 0 1 2 1 2
GazipurTea Estate 6
LawacharaNP 40 11 42 11 42
Chautoli 2 1 4 1 4
Adampur 13 8 21 8 21
Horinchara 6
Rema-KalengaWLS 8 2 2 2 2
Satchari NP 11 2 7 2 7
South-east(25sites)
Dighinala 7 1 2 1 2
PablakhaliWLS 7 1 4 1 4
Ramgar 6
Korerhat 6
HazarikhilWLS 8 1 4 1 4
Bishari 2 2 8 2 8
Bengdepa 2 2 7 1 2 3 9
Kamafuli(Kaptai NP) 27 23 78 3 6 26 84
Rampahar(Kaptai NP) 9 4 14 1 2 5 16
ChunatiWLS 11
Satghar 6
Fashiakhali 6
Bamu 5 4 14 4 14
Thanchi (Tindu mouza) 2 2 4 1 2 3 6
Khudhukoza 1 2 5 2 5
Dopachari 3 2 5 1 2 3 7
Sangu 1 1 2 1 2
Alikadam 2
Rajghat 1 1 2 2 2
Bhomarighona 8
Himchari NP 7
Inani 8 2 6 2 6
Ukhia(Thankhali) 9 5 14 5 14
TeknafGR 6 1 2 2 2
UpperRezu
1
TOTAL 250 80 258 12 24 96 282
a. numberofHG groupscalling x2(individuals/group)
b. numberofHG groupscounted +numberofHG groupscalling.
c. numberof HG individualsseen +estimatednumberofHGcalling
forestpatches,havingsufficienthabitattoholdlargenumber 9 individuals vary in terms ofimportance. Some have been
ofHoolockGibbons(Islametal. 2004).Extendedmonitoring evaluatedentirely(e.g. Lathitila,Rema-Kalenga,north-east;
activityinthearearevealedthelargeststrongholdofHoolock andDighinala,Pablakhali,Hazarikhil,Teknaf,south-east)and
Gibbons in the country with 84 individuals. Rampahar Beat areunlikelytohaveanymoreindividuals.Otherpopulations
(alsowithin KaptaiRange),slightlyseparatedfromKamafuli havenotbeensurveyedadequately(e.g.Thanchi,Kudhukoza,
was noted to have 16 individuals, further increasing the Dopachari, Sangu, all in the south-east) and more thorough
numberofHoolock Gibbons in the area. surveys in these areas could yield more Hoolock Gibbons,
The rest of the scattered populations of less than althoughthesouth-easternregion,ingeneral,hashada more
J. Bombay Nat. Hist. Soc., 105 (1), Jan-Apr 2008 21
)
POPULATION STATUSAND CONSERVATION OF HOOLOCK GIBBONS IN BANGLADESH
devastating history ofdeforestation (Gain 2002). PopulationssuchasthesingleGibboninRema-Kalengaand
The “forested lands” administered by Bangladesh the few odd individuals each in Shagarnal, Hazarikhil,
officially represent about 17% of the total land area of Teknaf, Inani and Himchari may have a better chance of
Bangladesh, althoughthetrueareaofforestcoverislikelyto survival ifmoved to areas with betterhabitat (e.g. Satchari
be less than 6% (Gain 2002). Within the forestlands, there in the north-east, and Bamu and Ukhia in the south-east).
areabout 16protectedareascategorisedintoNationalParks, Thesemanipulativemethodsmaybetheonlyhopeforthese
WildlifeSanctuariesorGameReserves(KabirandMuzaffar individuals and needtobe seriously considered.
2002).Theseprotectedareasarerecognisedmerelyonpaper. We conclude that the total population of Hoolock
Illegal harvestingofforest products (timber, fuel woodetc.) Gibbonsin Bangladesh inthecurrentestimateishigherthan
continues unabated, often in connivance with the forest thatmadeinthenineties(around200individuals,Feerozand
officials. Most of the areas within protected forest patches Islam 1992). However,manyofthepreviouslyimportantsites
are fragmented and have areas of agricultural land, small (e.g. Horinchara, Chunati) are now devoid of Hoolock
villages, grazing land and other human altered habitats that Gibbons and this is cause for great concern. Conservation
makethequalityoftheseareasextremelypoor. Inspiteofall action should be directed towards protecting the remaining
these majorhabitat problems, the Hoolock Gibbons present Hoolock Gibbon strongholds from further degradation,
in various protected and unprotected forest patches show translocating genetically compromised populations and
extraordinary resilience. The minimum assumed viable restoring forest lands through plantations of mixed native
population of Gibbons is 10 individuals (IUCN 1994) and plant species (Islam etal. 2006). Public awareness is on the
this is supported toacertain extentby mathematical models rise and the Government of Bangladesh is a signatory to
(Moluretal.2005;Islametal.2006). Manyofthepopulations variousbiodiversityconventions,thefuturecouldholdsome
noted in this study are much smaller in size than this promise if immediate action is taken in attempting to save
theoretically viable minimum and thereby regarded as theremaining HoolockGibbons.
genetically destined toextinction.
ACKNOWLEDGEMENTS
Immediate cessation of deforestation in all the areas
above is required. Since this is very difficult to accomplish
given the socio-political dynamics of each region, at least WethanktheUSFishandWildlifeServiceforfunding
safe-guardingtheimportantfruitingandsleepingtrees,along thisprojectthroughitsGreatApeConservationProgram.We
with protection of some closed canopy forest patches is are grateful to the Forest Department ofthe Government of
essential (Islam et al. 2006). To supplement the protection Bangladesh for access and accommodation at many of the
and preservation of forests, habitat improvement and study sites. The work would have been impossible without
restorationinmanyoftheseareasshouldbedone. Plantation the efforts of many students and volunteers. We thank the
ofmixed fruiting tree species may be carried outon a large Departments ofZoology, Jahangimagar University and the
scale to attempt to restore degraded habitat where suitable. University of Dhaka; and the School of Environmental
Careful examination of all areas with Hoolock Gibbons is Science and Management of Independent University,
alsoneededtoassessthefeasibilityoftranslocationofdoomed Bangladeshforpermittingandfacilitatingresearchactivities
Gibbonpopulations intoareasthataredoing relatively better. atdifferent study sites.
REFERENCES
Ahsan, M.F. (1994): Behavioral ecology of the Hoolock Gibbon in distribution and conservation status. ENVIS Bulletin: Wildlife
Bangladesh.Ph.D.Thesis.UniversityofCambridge,Cambridge. andProtectedAreas 1(1): 92-101.
Ahsan,M.F.(2001):Socio-ecologyoftheHoolockGibbon(Hylobates Das,J.,M.M.Feeroz,M.A.Islam,J.Biswas,P.Bujarboura,D.Chetry,
hoolock) in two forests in Bangladesh. In: Sodaro, V. and R. Medhi & J. Bose (2003): Distribution ofHoolock Gibbon
C. Sodaro(Eds): The Apes: Challenges for the 21st century. (Bunopithecushoolockhoolock inIndiaandBangladesh.Zoos
Conference Proceedings, Chicago Zoological Society, Print18(1): 969-976.
Brookfield,Illinois, U.S.A. 286-299pp. Feeroz,M.M.(1991):TheecologyandbehaviourofHoolockGibbons
Chivers, D.J. (2001): The swinging singing apes: Fighting for food (Hylobateshoolock)ofBangladesh.UnpublishedM.Sc.Thesis.
andfamilyinfar-eastforests.In:Sodaro,V.andC.Sodaro(Eds): JahangimagarUniversity,Bangladesh. Pp. 212.
The Apes: Challenges for the 21st century. Conference Feeroz, M.M. (1999): The ecology and behaviour of the Pig-tailed
Proceedings, Chicago Zoological Society, Brookfield, Illinois, Macaque (Macaca nemestrina leonina) in Bangladesh. Ph.D.
U.S.A.1-28pp. Thesis, UniversityofCambridge,Cambridge, pp. 402.
Choudhury, A. (2001): Primates in northeast India: In: Gupta, A.K. Feeroz,M.M.(2001): Speciesdiversityandpopulationdensityofnon-
(Ed.): Non-human primates of India. An overview of their human primates in north-east and south-east of Bangladesh.
22 J. Bombay Nat. Hist. Soc., 105 (1), Jan-Apr 2008
.
POPULATION STATUSAND CONSERVATION OF HOOLOCKGIBBONS IN BANGLADESH
Ecoprint8(1): 53-57. -The WorldConservationUnion. Bangladesh. Pp. 31.
Feeroz,M.M.&M.A.Islam(1992):EcologyandbehaviourofHoolock IUCN (2004): 2004 IUCN Red List of Threatened Species.
Gibbons of Bangladesh. Multidisciplinary Action Research www.redlist.org.
Centre(MARC). Dhaka,Bangladesh(apartofNORAD/IUCN Kabir, D.S. & S.B. Muzaffar (2002): The review ofthe present state
supportedenvironmentaleducationprogrammeinBangladesh), ofprotected areasofBangladesh. Pp. 389-403. In:Tanveer, S.,
pp. 76. M. FerozeAhmedandA.B.M. Badruzzaman(Eds): Bangladesh
Gain, P. (2002): Bangladesh Environment: Facing the 21st Century. Environment 2002. Bangladesh Poribesh Rokha Andolon
Society of Environment and Human Development (SEHD), (BAPA),Dhaka.
Dhaka. Pp. 341 MacKinnon,J.R. & K. MacKinnon(1987):Conservationstatusofthe
Gittins.S.P.(1984):ThedistributionandstatusofHoolockGibbonsin primates ofthe Indo-Chinese subregion. Primateconservation
Bangladesh. Pp. 13-15. In: Preuschoft, H., D.J. Chivers, 8: 187-195.
W.Y. Brockelman and N. Creel (Eds): The Lesser Apes: Molur,S„S.Walker,A.Islam,P.Miller,C.Srintvasulu,P.O.Nameer,
Evolutionary and Behavioural Biology. Edinburgh University B.A. Daniel& L. Ravikumar(2005): ConservationofWestern
Press,Edinburgh.400pp. Hoolock Gibbon (Hoolock hoolock hoolock) in India and
Gittins, S.P. & A.W. Akonda (1982): What survives in Bangladesh? Bangladesh. Zoo Outreach Organization/CBSG-South Asia,
Oryx16: 275-281. Coimbatore, India. 132 pp.
Gittins.S.P.&R.L.Tilson(1984):Notesontheecologyandbehaviour Mootnick,A.R.,E.H.Haimoff& K.Nyunt-Lwin(1987):Conservation
of the Hoolock Gibbon. In: Preuschoft, H., D.J. Chivers, and captive management of Hoolock Gibbons in the Social
W.Y. Brockelman and N. Creel (Eds): The Lesser Apes: Republic of the Union of Burma. AAZPA Annual Conference
Evolutionary and Behavioural Biology. Edinburgh University Proceedings.
Press,Edinburgh. Nijman,J.(2004):ConservationoftheJavanGibbonHylohatesmoloch:
Islam, M.A. & M.M. Feeroz (1992): Ecology ofHoolock Gibbon of population estimates, local extinctions, and conservation
Bangladesh. Primates33(4): 451-464. priorities. TheRafflesBull. Zool. 52: 271-280.
Islam, M.A., M.M. Feeroz, M.M. Kabir, S. Begum & S.B. Muzaffar O'Brien,T.G.,M.F.Kinnaird,A.Nurcahyo,M.Iqbal&M.Rusmanto
(2004): Conservation of Hoolock Gibbons (Bunopithecus (2004): Abundance and distribution ofsympatric Gibbons in a
hoolock)ofBangladesh.TechnicalReport.U.S.FishandWildlife threatenedSumatran RainForest.Inti.J. Primatol25: 267-284.
Service. 52pp. Preuschoft, H., D.J. Chivers, W.Y. Brockelman & N. Creel (1984):
Islam, M.A., M.M. Feeroz, S.B. Muzaffar, M.M. Kabir & S. Begum The Lesser Apes: Evolutionary and Behavioural Biology.
(2006):ConservationoftheHoolockGibbons(Hoolockhoolock) Edinburgh University Press,Edinburgh. 400pp.
of Bangladesh: population estimates, habitat suitability and Rashid,H.E.(1991):GeographyofBangladesh.DhakaUniversityPress
managementoptions.Technical Report. U.S. Fish andWildlife Ltd. pp. 529.
Service. 48pp. Ross, C. & N. Reeve(2003): Survey andcensus methods: population
IUCN/SSC (1994): Javan Gibbon and Langur population and habitat distribution and density. Pp. 90-109. In: Setchell, J.M. &
viabilityanalyses.Asian Primates4(1): 1-8. D.J.Curtis(Eds):FieldandLaboratoryMethodsinPrimatology.
IUCN(2000):RedBookofThreatenedMammalsofBangladesh.1UCN Cambridge University Press, Cambridge.
J. Bombay Nat. Hist. Soc., 105 (1), Jan-Apr 2008 23
