ifrllt.M( ~ p~ - f\ ~\f --c;)5 + 1.
r77 I) -n IiJf~J 44 1994, 3 29
:J / :J", )( 7/{v= / F +1E1L0I11K~J@\T.:5:1" I) =7 (Gorilla gorilla gorilla) 0) ~NJtm}EC: ~N1idJJX;O)!ttf11&
Population density and group organization of gorillas (Gorilla gorilla gorilla) in the Nouabale-Ndoki National Park, Congo
Tomoaki Nishihara**
The population density of western lowland gorillas in the Nouabale-Ndoki National Park, northern Congo, was estimated both by the "bed-census" method and the "counting" method based on bed-count and direct observation. The density was calculated as 1.92 - 2.56 animals/km2 and 2.29 - 2.61 animals/km2 respectively. Because this was the first time to attempt the "bed-census" method in the Ndoki forest, direct comparison of population density was possible between western low land gorilla populations at all study sites. It was concluded that the density of the Ndoki gorillas was highest. High population density of the Ndoki gorillas was considered to be possible because they have access to a wide repertoire of foods such as highly nutritious terrestrial herbaceous vegetation (THV) and various kinds of fruits and seeds, corresponding to the seasonal fluctuation of food availability. Although the feeding habits and habitat were different between western and eastern gorillas, they shared a basically one-male group composition, large group size, and unit groups that largely shared their home ranges with each other.
et al., 1993)0 =-:/ 0 -7'/ 1-' :::{I) 7 (Gorilla gorilla gorilla) IC-::>~ 'Lli, A-:fittJ{113llt-c.t>0 ~ c c~ .l) 0 ttll J:!.~ O):{IJ 7 0) [email protected];It0)tlnrw.; i- 0) :{ t*I*JO).fJlWO)~~ :6'';iffffl@l{*1J? '/ He J: 0 Itlt ~70)~@~ll~0)~*~~~m~~4~oo~ HIJE';i:JoOJ:pnL~'tJ:~\o U1.~-C, =-:/0-7 '/
~1~ -C, "< 1) '/T '/ :::i I) 7 (Gorilla gorilla beritlgei), ,...::tl) 7 0)ItltffUE Ie Ii, r~':1 "".-e,/-tj-.Af!J l:: if ~ 0 - 7 '/ I-':{ I) 7 (Gorilla gorilla graueri) ("bed-census" method) (1J':t!,/: Tutin & IC-:J~\Lli, rMJ{*l&fifl~fld <"direct count" Fernandez, 1984; CP!k:77 I) ;f} : Carroll, 1986, method), -:Jj;~@I(*;f}1)'/t-~~,;t ""1&1)1)'/ 1988; Fay, 1989; ::J '/::J' : Fay et ai, 1989; Fay t- IcU·:j"~\Lltl.lttJ{~11l ~ n L ~ t::. ;/ r' +T'i ~·I) 7 O)*AE\f.:f.Jbjifl!!.O)c'O)~:i!lt~ .J: I] b ~~, c C. hi. eni TO)1.J;itle.J: -:> LflH5 ~ n L~' 6 (Kuroda. 1992; Yamagiwa. *~~; ~ftli!l c. M\j'l!iJUJru' Mitani et a!" 1993)0 l;6)ltJhi G. cni'{';/ IDfJ1fll!!.'i, ~;/ ~·:jl*lm;;< 7' /< v = ;/ V +IT!YrL 1:+T'i~ ..) r" -iz;/-irAt.ttJiffJ~'GnLctJ.;6) 0~J*J le~uTi. ~ ~1/: (Nishihara. ~V'n1lp)o IDfJ i!i -:> 1:0)r:. -==-:/ 0 - 7 ;/ r'~· I) 7 o)ll!!.lilil~'{'O)m JUl/1fHi199UfI2JJ;6) G1992$11 R '* "'CO) 12 "T t:I. IEli~U::[jH-t!lU~1" 'i~iJJfjBTJs iWdfi~'i. =Frf01t1~tO)~~1} 6 C c. -:> 1: 0 1: C 8i- 287 EI,mT ib -:> 1'::0 T~fill'i. ;/ r' +0) ~" I) 7 i-x;J,%~I<::~ ';t V • -iz ;/ *fTib 1]. M1:.Ii. A '7 ;/7':f..t;. Gilbertiodendron ~ -It AtEle.J: 6 \f.' JJr ffE;g i-:to C tJ, -:> 1: 0 IF.J 1<:. t-f. iItfjJi::t-fO) 3 117'I<::}'J.lIJ~n60 1 ~TO'if:f:j* Kuroda (992) c. Yamagiwa (;kr~£D let Mml* (3J'l;6'G11J1iT) c.~* 02fj;6·G2JUT) txm)Ef1de:lkj'~' 1:~,[1,\$}S[ b;j(~ 1'::0 *liJfJ'i:O) 1<::. ,*/:m:JflI:.H(ltUUGL:;L~W:~* (4fj;6·G EJ (J~O) --:J Ii. ;/ fi +0)::( I) 7 O)\i'il!tf1UtMI i-. 9JJ'1T;Y...rF. !p.,c.~.ltX~f-c~\oj) c'1>utJ~* /V4-0~0)~~~0)-==-~D-7/V~~70)1: 00Fl ;6) G 3 ):J '* '{') C: Ie)} rl .; ~l6 (Nishihara ft. C: [illJiHlfQ-g- 6 L c. T. C ~l '* T c' O)ll1Jtj~ J: IJ & Suzuki, iVlIJINJ)o iJtJfi!I1JIL';l:. ~"I) 50)'i;/)· b ~.@, \f;/JrhijUj ~'c. mf~ ~ ~l L ~ I.:: ;/ I: +0) ~,. I) 7' ;//.;' /' y - (Pan troglodytes troglodytes) '\-> f:: ~ fIj~JiH1" flliO)Uhf11'J:fH(jhsri'il/frIY-Jle~,@, ~'6 :7 ®\f;/1( 6 c c. T J) 6 0 0)1l!!. 9 l T *liJfJ'CT'i it.::, ;/ V4- O)~· I) :7 O)l1H\L*~JO) C==:fr. 1990a; Mitani, 1990b)0 rm~liiS'i±'le* ~tM~[]lmO)fIJfI]tiJtO)mttrie :i!It~ mI&:. mQj-lt 1 7:. ';t I, '7 --.? :IX Ie ib 6 '/r) itio) oj tJ. ib '* IJ L -:J ~'L ~~. 7' r) ;/ j- ;/ ~. I) :7 "iJ I:: jl:/ 0 - 5 ;/ 1" ~"L ~'tH' ob 0) i-flJJIll. T ~ 6 rl~ IJ ll!!HlU(.j(liJ F ~. I) 70)1: n c.llfX l. ~' I) 5 JT~IUo rl6tlU] I] hi1=, L:; tJ ~'J: oj Ie L 1'::0 '* 1.::1i ~'Ie Ii'f'V-ff'"9 *~1&:0)1fW:le-:J~'L~~ l t.:: o 6 ~ti=fUU;H3~±O)rIJ91w.fJs 500m <.; ~'Ie tJ, 6 J: oj IcAIl'8tJlfl~liiSbi&AELt: (~1)0 o INLAND FOREST ~ SWAMP FOREST ~ OBSERVATION ROUTE ~ FRUIT CENSUS * CAMP ROUTE Ii :s.2 tI+-tt--t'lo.ft~a---f-"-~ 500m o Dr ~ PtJI-~~~"-=f,{::-=1\:-*~1 '---' 500 m Fig. 1 A map of the study area showing observation routes and fruit census routes. The Inland Forest combines Ci !/Jert iodendron Forest and Mixed Species Forest. The study area is . divided by grids of 500 m square. ilH~lfl~ c« "/ r ~AiI!Lt1:J) GO)~2=). ~«';I rO)f14fJxm~~~clfk ~~7~~~U~lk~~, ~~lfl~lk@~ It.:o j;t.:. ~0)~f1li~0)~.:tO):toJ:~O)t1iJ: C. ffPi, r 7 ~ ;./ 7', f!*ftff. :i.21mlJff. ~tJ c: tliti [X 71 ~ £< VT c ~ tL 'L ~,~ (Schaller, 1963. 1:J) G7¥i£tJ iBJJ GtJ)ICli'(j;W~ tLt.:1Wf4>O)~.s1&, :to J: Tutin et al., 1992) o)T, *li)f~IC:to ~''L b« ';I r ~~tLGO)tt~~77~~~~lko k~l*m -If1 t-m[iliO):toJ: ~O)f"JV(,~~~t.:(\f)IC. ~!I2= JETli, jC{tlc1Wf*f&~;IJ?;./t--r'~t':c*'Jt!Jil tLt,:~O)lkff~«,y rC clcHiJllILt.:o t.:~~o)h~7HrrO)M~cIt.:o ::( I) 70)« 'Y r Ii. T;./ /'~;./ ::;: - 0) b 0) c I~J]IJ «';I r . ~ ;./-If~ti; -t~t.:(\f)lC, ::(1) 7tJiifllt.:c*rJtttT~tL~ Ii, ~O)Jfilfj:l*~'], t14tVZtill~))O)t1~. to J: U:« 'Y HE~ffi c )1/- I' tB~ 'O)~ ;./ -If A ~ffi c O)t1iT~To r IcIIPH~T ~ ftffl{O)t1 ~ 1:J' G. f~Jll~ 3 EI 0r~ c ID1iJ:J!iWJrfJ9 rI1 , fiJfJ.td (, ts. -::> t.:mw~ =-' -tt ~ 0))1/- t1EJE ~ tL ~ b O)t':'11 ~~c£'} l t.: o t.:t':'l.' (,0)fi1!. t-~..-{ ';I t-' • ~;./ -It ~ )1.'- t- c L t: (Nishihara Ul1&G1&hiiE6'(fIC 3 E1TtH'iJJfj~tlb:'i\5l;ll 'L. & Suzuki, ~V~i[P) (~l)o fijfJ llill. ilH12@) 71~O)M.Clk«~rO)t1~~~mm3B0~ O)m~~ ;./ -if ~ rplCJI/- t- rd~ '0)~iJ)20 mN IC:9~.w. ~nt:«';1 t-'~i-, ~;./-tt~lC1:J' t,H'l4 B0fi'.1-r'JJ ~ c l t.: o f5!!Jllm 3 - 4 E1Ja r-lt1 t-O)«,y ~O)bo)IeIllUElt.:o)li. !j!~'~~T3 - 4 Be' 1J>-:>t':«';1 rf&c-t~o ~ ;./-If~)I/- Ha~'O)« ~tJiJMI11-t~ (, c tJiJJ I), ~ O)t.B.i-&±« 'Y r ~tb ';I r,j:-t«'Lft!i!.~tL~(,c~WimcL. tll~:M' 11-f;.l« ") r hi« ';I t·... c l 'L'¥JJj]IJ L1!tt iftJt.: -til1.-O)..-{ ") r j; t:li, ~«';I r O)tJ ~ tJ{filJ */iJf9E-r"i« ';I r O)~Hfift 0 tJUiiJllJ5E LtJlJ) -::> t.: o L::-r'JJI:J, 1:J)-:;I~t~«';1 t-'lmO)~§~tJilOmYJ.r~iJi) L 1:J) L*/iJf9E-r' Ii ~ ;./ -if ~ x;t~ ~t'Ffjx~ 3 B j; t.: ~Hi~~«';1 t-'tJi t- V-)I/ (-¥JEBJl;~~tJC1J) Ii 4 B Jap.]O)tJT L ~,..-{ 'y r IqU5E L t.: 0) -r'. f'FfJx G~~70)~l:Jmc~tttTT~~l1bO)m)-r'-:;I~ 1:J' G 5 El Hl:fl~ L t.:« ';I t-< Ii ~ ;./ -If ~ Ie 1:J'1J' G tJi-::>'L~\~ 2fTM0..l.0)«';I rO)~t5c Lt.:o :J'I) tJlJ, -::> t.: (, c IOJ 1'). «'y rO)%1f!tBtxli 3 B'1 70)« ';I t-'-if-{ t-li, .:tIC t- 7 'Y 4-;./ 7"ICJ: -::> 'L t.: 'i 4 GlCifl ~ t#!;t t.: o ~.Lk~, ••IeU••l:M~e'RAlkbO) b~ca Lt.:o ~«';I t-' -if 1 t- Tli, «';I r -If 1 t fTM f* 1&*IE $ O)!1H£.!I!l:O)fi'LiR, tilEt:., 15~, «';I r~t1 t-~O) *m~-r"i, fTMf*1&ffE5E$IC J: -::> 'L1:.\ll,iWl*1& «';I r 1&. :fr« ';I r 0)~rfJ~(8!'iCi[l (~U:« ';I r 0) O)ffE5Ec1:Am~O)nilib~hko~cL'L«~ 3 32 t-' tJ., /' I- ~ffl ~'. illjj~ll1.r,~COtiM'iMiJiUt.JlqIJ 3 'r fJ c e: le1Wi4>:~lffiXE~!i-.@jfTj L t.: o ""J;I; ~. ffl L t.: o c::. COtftiE1!-a:-ffl P Q C: ~ 1L[IN ~. r< '') r ~1!HtJJru'i- 3 'r fJ C C: Ie 41UlIe$t1j' on [ Wl : 12 'i~:Oi~.w.~ nt.: bCOlLmUE L t.: o 1""Jcor< ';I t-' J'j-2f:l, *UWl: 3f.l-SfJ. mw1fJ.I: 6.FJ -tt-1 Hi 1 ""JCOIIHiImmlCf£l~-gQc:ilX):EL, 2 8f.l. mIYJl1J: 9f.l-llfJ). ~Wlle""J~'LWJJ(m rz-.~lem~-g.Q1.i1 jtlHi~O)i* ""J CO r< ';I 1-" -tt -1 I- le:t-H' L, ~r< ';I t-' -tt -1 I- CO r< )i:i-:to c::. tJ.., t.: o I #~.~J: Ii[I:i)-CO !\itiLW:[] CO bCOC'3S.Q e: L t.: o Mmj~'i $mJJlJit.5~C'.CO"*ff:{kf~:OiJ: < tJ 7J'''' t.:'W. I /&IJ'IO.£.Q J: oj le~:!.R:mi-iRQ) t.: o c::. n GO)~i* IVjUl'Htco~·I'a\IJlJifflml:3S..,t.:t.:66. r<,:/ r-tt1 i- b c ICB.TO)1&fi!!i-31<:Q)t.:o CD, r<';1 I-'mlIlC.··c I- m[]COl1lJJxJUxi- b e: lL1§-m8:l~mJ.E L t.: o ;I; t.:~ltllle:to ~ O)r< ';I I-'ncot.%,f[l UI111!C'r< ';I r i-fJ: Gt,H' 7 tJ r.t iTZ-Y-:,J!lH'I!-tt -1 ;;( i-. 'J I) '7 I) - i /';f."O)1&Iia;l;ntJ~' (Schaller, 1963))0 0, aU~i5"c &!;;I; tH 'lJ.,~i1IC)}~tL~WL t.: o CD IL 7 tJ /' ;f.' ., ?rti lE i-;(3 c. t.£ .., t.: iE:mS:l~~@f4>;1&o @, jj[Jtn~leJ: .., L6rH~.~ ;I1J.:W:[]CO oj iJ, lMI1t ~ 1& cmf.IllllljXtli c'O) r< ';I nnm e: b -iX L tJ ~ , m[]O)@i*~o 0. irH~ttlH~C'nJjG;I,plL8l1tJ:.QiL\H* w~:l!ilUlru9rp, A '7 /'7°iii~'O)lJl~li37J'GA '7 /' e:~~~nk~~9~-1&00~CO®-0~.W 7"t,f\i-fIJJTI L L~'.Q =r'I) '7 tJi~J1 ~ ,e @~ ~ tH.: LL~••~CO~~Q@f4>;~i-*~. ~ni-~ili (Nishih,ara, ~-omr:p)o ::1' I) '7 tJi~ ~J;ue c'cof!'E1J( .~ffll:~",L~m*~i-~WLko~ili~Q)W COI1:.~COA '7 /'7°#i-fIJm L L~'Q;f)/i):£;f)'C'(i fJ'Ui, tt!!~ J:C' )}*,) L t.: sao m ~!:l)j 0) ~,.. 1) ';I I..';/)' tH'tJi • Jj.>tJ < e: bl~il!lt*ICr~f~97.>A '7 /'7:U G31<:Q)t.: (j'g) 1 )0 'i-gr Table 1 Gorilla group composition: fully counted groups only. Group A B C D E Date observed Dec.12.'91 Feb. 10,' 92 Apr.17,'92 Aug,15,' 92 Oct.28,' 92 No. animals 6 9 9 5 1 0 Composition SB 1 1 1 1 1 ad 1 3 (2) 4 (4) 2 (2) 3 (3) y 0 1 0 0 2 j 2 2 2 0 2 i 0 2 2 2 0 ? 2 0 0 0 2 so: silverback; ad: adult (( ): females: age I sex class of others unknown) y: young; j: juveni Ie; i: infant: ?: animals whose age / sex classes were unknown. i"0){@li23.75km2 (95:7'I) ".I t-'xO.25km2) C', i5.., t.:b{, {~b ~:6'.., t.: 0) Ii, tt1i~i-fIJmitTIC i"0)?!>8.00km2 (32:7"') ':./ rXO.25km2)b~A'7 ±O)J:. C:I:A:; ':./ n "1 t.:'itt!JJ:'.O)t~nmO)J:. (fiJi /,7"f*i-~U:7'I).:./ rC'i5-:>f.: (~1)0 hmA:;7r)i-i"0)"1"1A:;7rClL~mT7.>~ ~C'i5..,t.: (51.9%)0 jfIJ*O)J:.i--'CO)"11:A:;.:; r mHJiG~ ClL.fIJJlIj-7.>t.~~ (ff1J*A:;.:./ n Ij,fK;lel:6d i IDIJ~lDlru9rjl, :l'I) 7 o)ifit~lQ~'i93lilli5 -:>t.:b~, 1P..,t.: o jri*cf:l~*~ll:.')(:T7.>C. j:~t.:lifiJih 7¥:~IC1J r) /' t-b{C'~t.:-r-Ali31@l(33.3%)t.:· mA:;·:; I: IHil:*/e ~ <, titHY.1A:; ':./ r '\'>'ML/:le fF G 7b~ 2 W'<::,i5..,t.: o 31/ill0)?!>, ') I) 9 I) -O):l' I) h7.>A:;·:; r (-lMJ:A:;,:./ n liffi*le~1J>..,t.: (x B.W.~h~lillD~.b~<~lill~, .~O). ~~)E: d.f.= 3, X2 cal= 177.841, P IIlJ\~O)~Jj:jYIJC'li, 11HiL!tH'llli llillO) '/)l//,{- /-: ':./ G:IJ>l'1j2*~tJ~1:lefIJm~h (74.7%), b..,cb :7 c UiDO);;f I- T (1: elL ~ A), i" l LtUXO) frJfMJiI!rtJ~~J:6>..,t.:O)(i Pa/isola spp.C'(36.35bJ, ::I t-''E:, 71J /,;f.·r)leJ: ",LtMnX.~nLl't.:o -::>l'"'(' Haumania dancke/ma71iana (24.1%)"'('i5 ..,t.: (1<.2c)0 MLI:« ':; rO)J'iil.I~ 'i20mb~Jlt~-c A:; ':./ r 0) 9 117Ht i5..,t.:b~. 5 -lOmO)bO)'i33.0%, 5mJ.:.FfO) ~IUit~~IUdl'L, ::1'1) 50)A:;,:./ t-'-tj-1 t-li75 bO)'i51.6%i-6~t.: (:2( 2d)0 tMJ:.A:;·:; t-'O)SJ!. -rfff. H694@0)A:;,:./ rb~~C~~ht.:o A:;.:; t-'-tj ~O)i%~ Ii7.4m ~ Fig. 2a Distribution of direct observation sites of groups only (A-E; see Table 1) and bed sites only during the I period (1-17; see Table 3). I t) 34 Tuble 2 Gorilla bed categorization ( a) VegetaLln of bed site Total s G M ? No. bed site 75 1 8 63 3 % 1.3 10.7 84.0 4.0 S: Swamp forest: G: fiiJ/Jertiodendron forest; M: Mixed species forest; ?: no record. ( b) Spatial posi lion and mater ial composi tion of goriJ la beds. On the ground In trees Total Bare ground Dead leaf Bed on Plant bed bed bed fallen trees No. beds 694 319 41 3 222 109 % 46.0 5.9 0.4 32.0 15. 7 Dry season 245 138 37 1 52 17 % 56.3 15. 1 0.4 .21. 2 6.9 Rainy season 449 181 4 2 170 92 % 40.3 0.9 0.4 37.9 20.5 Bare ground bed: gorillas slept on the bare ground. Dead leaf bed: gorillas slept on the dead leaves on the ground. Bed on fallen trees: beds constructed on fallen trees. Plant bed: beds constructed with plant materials. such as herbaceous plants. When the number of beds was compared between dry and rainy seasons with X 2 analysis. 'bed on fallen trees' were included in 'dead leaf bed'. (c) Major plant material composition of plant beds. Species Family n % Pa/lsOfa Spp. Commeli naceae 86 36.3 Haumania dancke/maniana Marantaceae 57 24.1 //anniopb)'f.on fll/vllm Euphorbiaceae 15 6.3 Ataenidia conferta Marantaceae 12 5. 1 Jarcopbr)'nilllll prionogonium Marantaceae 9 3.8 J)aJbollsiea africana Fabaceae 8 3. 4 others 50 21. 1 237 n = number of heds where a plant species was used. -e /' -tt A mmW.6.65km 2 (332.34km x 0.02km) t:' ( d ) lIeight of beds in trees. ih~t:.o "":1 I:O)t.r1fll'i3 Btt:.li4 Bt:'ih~t:. '/)'G. L.nGO)txlir!~0.itleihTlj.Q)~ c. 1:..11', 2 Height (H) No. beds % tfinr'i. I.92-2.56iJJi/km cJ):!±J tttLt:.o tui1:. C c jC lj. ~ C. Gilbertiodendron **. ilV& f.ft:'-'C ~'Li"~'L, -e /' -tt A ~§'~fUi 131.69km (39.6%). H~5m 47 51. 6 200.65km (60.4%), ~2~1 ~ t:. o l t:.tJ{ ~ T, !j1ro:~§.~~t:. fJ 0)'" lOm lffi)£~ J: ~ Range: 2 - 20 m @)f*t:X Ie tfi IJHf.HE ~ I W1O)rIl9Ie~~2:.nt:''''':I 1-'-tt-1 I-O)tx'iI7 Maximum: 20 m t:', ~O)~J~'/)'Glj.t:'~"":1 V-tt1 HI~:ffiO)·UJ/i.X: Median: 5 m IUt ('" ':I I-'fFfi.X:@){*t:Xlem~-t~) cmfi.X:lH~ Average: 7.4 m 30) J: oj IOJ ~ (~2 a)o L O)*'/)' GVl.l~~I*JO) '" ':I I-'"'.t 1 ~ mffi~tJ{ft/J"etJ ~ J: oj le~m['lJ~ 'fi!./I)t:. o No. 14 c No. 15 litMfi.X:!ttx (I8) cfM1i.X:IJ{ l;ll;;f -3& l T ~,~ O)t:', f5.1-~ffi c lj.tJ l t:. o 1 36 Fig. 2b Distribution of bed sites found with the' bed census method' (a ...... h) . . a: 11 beds; b: ·8 beds; c: 7 beds; d: 10 beds; e: 8 beds: f: 1 hed; g: 5 beds; h: 1 bed. Table 3 Unit group composition in bed sites. No. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 , 91 ' 92 Dec nee Dec Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Feb Feb Feb 8 12 18 5 6 7 12 20 24 25 25 25 26 27 2 14 18 ------CD 5 3 3 3 6 1 1 3 (i) 15 16 2 - 10 23 10 13 2 ® 1 3 1 3 3 6 1 3 ® 1 3 7 609 2 4 11 6 2 5 5 o N 3 7 27 22 12 8 7 11 25 3 30 2 6 17 18 5 5 Data limited to 'the I period' (Dec. '91,- Feb. '92), when measurement of feces diameter was possible. The date is the day when beds were estimated to be made. d: diameter of feces; CDd;;;:6.5cm; @4.S::;;d::;;6.4cm; @2.0;:;;;d::04.4cm; @d<2.0cm; 1: d = unknown; -: no data; N: total number of beds including feces. Table 4 Fluctuation in the number of gorillas in the study area. Period II III IV Dec. -Feb. Mar. -May Jun. -Aug. Sep. -Nov. (a) (b) No. bed sites 17 17 8 7 2 No. groups estimated 8 7 3 3 2 No. beds of each group 30 30 13 21 8 27 18 8 11 6 18 12 2 7 12 8 8 6 6 3 3 2 2 total 106 79 23 39 14 ._-_._------._------.------No. total animals including 117 87 25 43 15 estimated number of infants. No. animals of groups 9 9 9 5 10 directly observed 6 6 total 15 15 9 5 10 ._-.------_.------._.------_.------_.-----.------.------No. solitary animals 3 3 3 2 .._--_.- Total 135 . 105 35 51 27 Density {an i mals/km 2} 5.68 4.42 1. 47 2. 15 1. 14 Average group size {including solitades} 6. 1 4.8 3. 5 4.6 5. 4 {excluding soli tades} 6.9 5.4 3.8 6.0 8.3 There were two possibilities.. (a) or (b). for counting beds for" the I period" *: (total number of beds) x 1.1 38 No. 14, ISJ: IJmf£fl1&O)~~' No, 3. 4. 9,ll1i~' ~\T. mI JUIO)tt}r:5crm~O):;1jt£C'1:.ill,illJ/4>:1&.:t -ttlb. ~,'liT£.&i~, H~fiJU: b K-JJ: L T~,t.H'O) 11tJE L I.:. (~H)o 4 JtlJru'.:tH:.fQ1'~ C, ~1"B!U~rt-] C'. C. C. T Ii 2 -:> 0) nJti~f!.1: i-fJJiI~ L I.:. : (a H,'4J£ O)1'..@,@I*S:'i. i~l)~IC1&t b ~ <, i-O)~-Jftix~ O)MIJ1:6'G No,3, 4, 9.:tfZt]-ffi,1i!:J (27lilD c L, 1> L.. '.:.IJi:l:j!jk,*0)ftil:1ili:JOIC' it ~ mnr ItIJ K mIll! L, No.11 Ii5.J1J~./mj (30DiD c,.JJ-ts.-g-; (b) No.9 c ~O)~ru&~1>Lko~MC'*~Ghk~Q*& No. II 'H!f)£0) Ficus recurvata 0) Jh] i2!. K 2 II tic itiO)iJ'-~JfI!1~c6c, 2.29-2.61iiIl/km2 cts.--; tlT~~~~1~i-m~kO)C'~-O)mrnc~~ t.:. o L, No.3, 4, 9, II IH'-ttL b IU] - W: Ell (30iilD c 9 ~o Ul GD.f~O)UHJlli. ~1~f,hJlIJIJCr:+7}tS. 1.:.1/), h~llx:rHJ:O):ill:IW/l::6> G, ~1Iir& 111& 12 ( No. 5, 8), 8 (No.2, 6, 7), 6 (No. 13, 16, 17). 3 (I) ~L[!.1'f,:lJt11tfEfk (No, 1,10), 2 (No. 12) 0) 5 ttEJIK7Ht'iLI.:. 0 1:..@@(*tx i-~1lli-9 ~ Ie it:) I.:. --; T'i. -e 0) iHfi LI.:.tJi--;T, (a) OYT-7..C'~'') ~~t1 1·:m:r:n:6' ~ .:tM1' t.:. &) Ie It!Hit'tmf,{TIll.J (*~~5JIJ L.. T fJ rJ /' ~ GiitiJllJ 2' tl ~ Ji,i:;J':m['lJ~(1.8 C', t{i~I:.,[J,n6JI/P& Ii 2' h 6 c. C lJi~ t L <, fI]J~rmf,Un(]O)« '') r"-tt 106 c ti I), (b) 0) I;- -7.. C'1HII ~ Ii 7, ~,1~illJ(* -1 ~ C'« '') ~ ~O) tJ '/ /' I' b tJ 2' ;/l;/l'J, J: I) iE ~mfllO)fIJlfjt~O)),~ ~(;l:79 c ts. --; t.:. o 'J I) -7 I) - .:tIl;)'; < /jz~t.Q.no\j(*1& 6'(fi2',j,J('r90 2' blIJIG:6,le (J)? !> 7 tJ /';j; rJ 0) L1jY) ~~~IJ0'i, /'IQ-T/iI5.7 2'tlT~\~O)tS. G, \f;IJtHbE/i~1'-1;t'eiE6rW:ts.~o % (Milani et al..1993) C liUJ 2' h~tJi, fJ 7::.1 L..ip L... ,1.M1HtHtl!HC' 'i -~I\W: mWlJi!~ <, iilil:. (I 1993), 0 ~ (Lope, ;tj':f- /') 0)10,896 (Tulin et r't~C.c'i~nJli~tJlJM:~·ni~~\o1.1.:., /"'-j'lt aI., 1992) .:t:J5'~1i: KA ;JLl5.7 % o)IJfUit~.z&) Kt2 tJi-/'7} IC~rOL 2' n T ~ \ ts. HJ\iJl C'It, l!'H~llI.r,~-? fJ'Hp T, :'t:mlilM'iI&FHX u) 1 ;J;IJ c.,1J- ts. L 1':'0 (a I. @(*~jJIHi-JWIfI~.uS. b 0) c tJ ~o L 1.:.lJi -;, T, (b) "Ul·f'tlO) I;- - 7.. 0) 1:. tJ.1M1I;HH= 7 fJ /' ;f;' rJ ;,j~lufJ\:C"H!.~Ht~Ie:tJU~::( I) 7 O)1:[email protected](*~.:t fif!iE.:t:ti e.ts. oj C, 86.9 (79 x 1.j)~116.6 (l06 x tr!.M1'~1':'~K, «,') ~1&o)fJrJ/'I'lCJ:~tiit 1.1) c:.ts. I), «,') r 'It 1 H~lJ):6' GffftiWI2' tl ~ 7 i-1:: c L.. T;fIJJlJ L.., [fH~ttJB$~1C J: ~ T - -7/i mi@ fJ /' ;f: rJ .:t g;- !lI1:.'1:. .\i.l- nM 1*S: 'i ~~J 87 ~ 117 Wi c ts. 1J~J'Ct&~J~' ~ ~mti:6' --; 1':'0 --; t.:. ('/1. 4)0 I~J JOJlUJ lil ICfc:'t: Ie flI.1I4,~tJljJ r'; /' 4-@)O)ID,~ilit.1iW"['IJjI G:6,fi 1 ? (C, ;i1M11.U!x/AJO) ~ 2' ;/l t.:. illi t~ ILQ t~ 0) \jJ (rIll i 2 (yIJ J0 fJ, A ~.r:lJ1fJ\ 9 1=.,G.J.illJIUXICliu;'jJUHel ~;{tgl!JlJi.1). G~ll.:.o mI i ~i» lin, B:mE.JltJ i 6iiJiC', HI5fiIlc·it:)-J/.:. o UlGI,I,j )DJ/e1:,liJ.llbHi'1J:tl Jtl 'b --; t.:.fillul c L.. T, CO) ffi[]li, HIlT£fHxct,I'iI&':6'G.1).T. ~\-nlb«'') U.IJUJ~Jj~~let~Q~~lT~\t.:.Celtis lIlildbraedii 0) ~ ~t 1 ~ C'6'UiW 2' ;/l t.:. mEl] c 'i-;1& L ts. lJ' --; 1':'0 ,tM:tO)jlJ: 2' tLt.:. o o)D~JDHim;l.f1:iili:lliO)Mfili:JV]C', ~~:i!U~r-n:::J' I) mUM, mmM, mNMK~n2'h~«7~~ 7 0).mE)H5U~:lJi!tJj~IC:to c. ts. ;/In T ~ \ I.:. c. c c I~U -1 1·1&/i, i-tl-e'h8, 7, 2 "['J,;, --; 1':'0 ~JDHe-:> f*L..T~\~0)C'as0? (Nishihara, ~Viil[tl)o c.oj lu Table 5 Population density, average group size, and maximum group size of gorillas. Habitat Location Density Group Size Reference Method (animals/km2) ml m2 max Tropical Congo (Ndoki) 2.29-2.61 4.8 5.4 30+ This study C -6.1 -6.9 1.92-2.56 B (Ndoki) 1. 87-2.07 4.1 1.3 12 Yamagiwa(unpubl.) C (Ndoki) 3.88-5.52 Mitani et aJ. (1993) L (Djeke) 0.90-1.60 30 Kuroda (l992) C (Ndoki) 0.2 Fay &Agnagna(1992) B (Mboukou) 1.2 Fay &Agnagna(1992) B (Motaba) O. 1 Fay &Agnagna(1992) B (Mhomo) 0.4 Fay &Agnagna(1992) B (northern part) 0.4 3.8 5.0 Fay &Agnagna(1992) B Central Africa Republic (Dzanga -Sangha) 1.6 4.1 5.2 13+ Fay (1989) B (Dzanga -Sangha) 0.89-1. 45 5.1* 52+ Carroll (1988) B (Dzanga-Sangha) 8.0* 18+ Remis (1993) Gahon (Lope) 1.0 16 Tutin ef. aJ. (1992) ? (nation totall 0.008-0.44 4.0* 19 rutin &Fernandez(1984) B Equatorial Guinea (Rio Munil 0.58-,0.86 6.4-1.1 12+ Jones &Sahater Pi(191l) C? Zaire (I tebero-Utu) 0.21-0.32 Yamagiwa et aJ. (1989) C Forest Zaire (Masisi) 0.83 6.3 8.0 11+ Yamagiwa et aJ. (1989) C Montane Uganda (Kayonza ' 59) 0.57 Schaller (1963) C (Kayonza ' 19) 0.31-0.43 8.8 11+ Harcourt(1981) C Montane Zaire /Bamboo (Kahuzi ' 18) 14.3 42 Yamagiwa (1983) (Kahuzi ' 18-' 19) 0.31 11.1 15.6 31+ Murnyak(1981) C (Kahuzi ' 90) 0.43-0.41 1.6 10.0 24+ Yamagiwa et aJ. (1993) C Rwanda (Virunga ' 60) 1.15 16-11ifc 30 Schaller (1963) C (Vi runga ' 13) 0.13 Harcourt &Fossey(198l) C (Virunga • 81) 0.68 Harcourt P.t aJ. (1981) C (Virunga • 86) 0.14 Aveling &Aveling(unpubl.)C ml: mean group size (including solitaries); m2: mean group size (excluding solitaries): *: whether solitary animals were included is unknown; max: maximum group size; +: excluding the number of infants because group size was counted only by bed sites; B: 'hed-census' method; L: 'line-transect' method; C: 'direct counting' method: ?: unknown; -: density estimate has not been done. 40 l t.: 1:,Ii.\fIMf4.:t$(O) WZJVlli , j>tJ 'iflhtlhtgto)..::. '/ 0 - 5/ I-':.:l J) '7O)\f;IJ[cUHJ(Wa T ;O>tj IJ flJ,l' (7& 5)0 v.1l GO)-t! / -ij-.7-. T'i r!J-~ \« TliillHHI.:'5(T ~ tJ, ~ '0 ';1 I--' b j-«Th rJ / I' ~ n Til IJ, e.t1 GO)'J.tt1fI /r4-0nO)"::''/D-'7/r~~50).fi~T Ii, Tutin & Fernandez (984) KiiI'LT, 52.6 0) If,' IS[ t1EJ.E lL LJ:, «';1 I,' • -t! / -tj- .7-. it. tJi JTJ ~ , Gtl., [Jc:L-T~'Qo ~G'c, ::1::«':1 H'Jnj~l~~«';I r @J(:4>:tlm~~t.5-1/· ~5/-t!;;I'it.;t.cnt ,HI!}!] EJ J: IJ 4 Ell] j;)J~i lUj 6 C, «;I F c L- T T~.7j-GnTl'tJ,~'t.:~lc, / F4-c{l!!illlJ:i.1cO) *1j}JIJT~tJ< tJ~ (*liJf~; Remis, 1993) O)T, rJl-ctffiJi:ltJJt i-@MHU5(-g6 C c Ii T~ tSiJ> -:> t.: {lX1L /' r 4-~it:T±«';I FO);!j'Ji'ltJi/;ll;l',iiJ LTiO (jf;f / : Tutin & Fernandez, 1984; rll* 7 7 ~ c -gnl;( Fay & Agnagna (I992) O)tfH.E{iU {: I) 1J • -t.t" / h'= -tt / if (Dzanga- Sangha) : Carroll, 2ff5L-t..:flfI, 9'tJ,n!> 0.4liJi/km2 tJi, *liJf~c 1988; Fay, 1989; ::J / ::J'~tl5f1 : Fay et ai" 1989; U~~.~.T~6~c~60 CO)tx.tJ~~~ Fay & Agnagna, 1992)0 @f4.:~*Ji:it.;li, Wd:l'tl: 0) t. 0) c 1-1.:«T ~ nO') T f!X;~ '0) Ii, -t! / -+f.7-. )v- I- 0)1:pC', «'Y 1-' O)~tH~~bqfr~' Gilbertiodendron 1-' 4'-0) ::1"1) :7 ,Ul:f!l!/pO)j]j-f0);i),h- Fay & Agnagna, 1992)0 *t::., :;I/;j{/'C"i.::l:«·Y 1992 ; Nishihara, t~ f/m [tJ ) 0 /' F 4'- 0) ::I' I) :7 l::t, r {>t~tt~« 'Y 1-' 'il;l e A., c.'tJ. ~ 'O)C' (WilliamSQn, f: O)!±.,lllJ}j'/tnO) *llri~f~le If::; L tj, tJ<.; t*tt 0, * 1008), t-t .E!. tf; IJt ~it! tJ{ j@ IJ\ ~ {jIfi ts; fL L ~, 0 ii] Ii~ t::.7-. '7 /'7o~[J-m·I'f.JlefIJm~0 c elcJ: -:>L, * t~Uiffr~'o 0t::.b{-:>L, /' F'4'-eillU~J:t~~tJ{pJfi~ tt: fUn 0) j-f:j ~ , i1!!.J:. t1£;£:'1>: M"\'J ~ fill ~ tVJ !ft5.t{> fJFf C'Jsoo ~fU:¥JJ l..o~- I- I) - e 0 t: (Nishihara, ~vtI1rp)o /' F' 4'-O):::i' I) "7 0)1:,@.7!.{filLliffHPJ b~ib I), WJ /' 1-' 4'-O)!l1;6dJ~Uf~JJl~J: I) -lffl~7)¥((.]lL;fIJm it±~(i 7!.{fiO)~[P-t 0 ±t!!±~ Ie ib t::. 0 t::. t/) Ie, f: 0) L- L ~'o ::1"1) :7 O)t*tt{T!JIJJh~, /' F 4'- 0)::1'1) :7 0) t!i W1:.[~ ~;J.f[ tJ 1L*iii'i(f.] leW<:!lJJJtJ -? 'J I) '7 I) -;t A 0) b C "'-f1f1f-t ~ C ~'-::> t::~!f~ 30lij'jtJ, c'O){YlJtJ{;j;) ~O),e)i;fG (Schaller, 1963 ; ~ b -::> L ~,~ c.. c Ii, c.. ~1 i -CO) "7 t) '/ T '/ ::ll) Yamagiwa, 1983), 0 «--e,;J:.fI',b@itJSJ5!i.n-c(Tutin 7 -? t: ff S/ 0 - 7 '/ r ::ll) 7 O)!iJf1E-c Ufl G;6' Ie ~ etal.,1992), «I) '/ti (Belinga, h";f,',/) -c~ h T ~ t~ (Schaller, 1963; Harcourt et al., 1976 19liJi-c.15 '""J t~ (Tulin & Fernandez, 1984)0 '/ I-'" ; Harcourt, 1978; Murnyak, 1981; Harcour't .of- T b oft 1 ;(0))..: ~ ts. Wlll Ii L n i -cit",-,- ~ ~1 L et ai" 1981 ; Weber & Vedder, 1983; Yamagiwa, :tJ G-cj", L tL* --e '/ r-.of- TiJ~U~ tLUN::A.:W:f11-+t 1983; LlIj;Jj!, 1988; Yamagiwaetal" 1993)0 4: 1 A"IiI2jl.fi-c (Mitani et al., 1993), 30liJj ~~;t !iJf9'C-CO)ItHt'llH'JfO)'IHyljlJ> G be)] G;6,tJ,l ")Ie, ~ oJ; oJ t.1 A:mli1:HHU'i.i ~ ~L T ~,tJ,;6' ':; t:: o G;6' G '::':/0-7'/ I-'":J'I) 7 0)tj1hlJHi1 i::> U/j>:O'-J Ie Ii 111 *i!JfJ\:'i, /' "'.of-'CWg{IQ):J" I) "7il~0)-+t1 ;(O)}.:.. ~ ~ ~,t~ ~ ~ t~ tjHl,Ult c·m f& LT (Tutin et al., 1992; tJ, W:EI'ltJSfj.{f-t' c.. c i: IVj G;6' Ie G 1:: 0 i * tllitanietal., 1993)0 ;{~~'j AO)r~l~-?;tAO)'J IiJfJtU),1I,~ilitt!Jo) ';1;6> Ie. '/ F.of- 0') x'iN T;j;) ~ '/ .L I) )1 I) - (t~/J~-J'ItJ.!f,ilj.::.:/ 0 - 7 /' /,"::i I) '7 T )FJt!JJl.t<::·t>~!~30JiJjU)«':J ,,-+t1 "-?17JifjUJ:!tEI'lI;; bi;c..tJ,~)tLL~'~ (Tutinetal., 1992)0 IA~tJs ~g!'~.fLL:tJ~) (Kuroda, 1992), ~ GlcrlJ'f!:T -::>L, :J"I) 70)IIH,'l*fJI0)/;:rlf!i'iIUifillv,,-,;:)v~.tJJ\ 7 I) 7; 0) off '/ if = -It, /' tiT L52JiJi C ~ \ oJ A·:!tlJIO') ~ ~ ~ {f{ElJ;tl1~';2'nL~'~ -}j;l;s{~~ .:t L b Ji.< ® G 'n ' L. c'iflU.itt; , ti , 0 () c "":) U) (Carroll, 1988)0 !tr'Jl'~ILHl:1J(O):/)v/'<- I-{ ':J 1IJi{f(I:'g- 6 {91j(i, tt!J.iI!\·HH*le~U;''. L.. Ui~~ IC'-W~rl~:tJ c.. ti ~ '. {fuji y ~ --e .15 ~ tJsW: U) :J" I) 7 T b [iij U):J' I) 7 C· b X[J IJslldULH-HHCiJ:..\I'.-t ~ t-H1dt ~ nt::*'iHlt.lil:t1-c.15 G~lT~'6 (Schaller, 1963; Murnyak, 1981 ; ~ c ~ \ ..'J t~ t:t ·t'1: -?)l:'.UJl\il1l O);i{t ~ 'tJ; .15 ~ Ie L 1.1' 1.1' Yamagiwa, 1983; Yamdgiwa, 1988; TUlin et al., ~) G-f, 1RUlo)-+t 1 A"O):k.~ ~ Ie Jl;jili".',i,fJ i <1) -0 L 1992; Yd01agiwa et al., 1993; Mitani et aI., c Iid:t::1"'9«~ TJs ~o 1993)0 4,liJf7'EIUs~'Lb, «':J "'.1tl110)t'i:ffMlII4 !It{iL:!tL-J:lMJ]c'O) fllIHJ$(O) .k.~Mti m:Hlli, TC',e JJX:lJs, Tutin et al. (j992) o)W~liiill fJ Ie $ltO).&lf r'f 1 )v'/ if0) :J" I) "7 T 1,[] G.fL L ~ , ~ IJs (Fossey c)[t!t~-t~ c-t~1'J (S/)v/-{-/"':/ :76,5c01,l;)1:. & Harcourt, 1977), fj.,r: /'0) 0« T' b [6J L c.. c lJ;m1ilii~tLL~'~ :t r -r (7'"7 ':J :7 /,- '/ :7 i t~ Ii:t r -r j A) 4.5 (Tutin eta/., 1992)0 '/ F.of 6,4cm, :J 1-'"-E2,O-4.4cm, 7f; /,;f't) 2,Ocm T U. Js ~ IUJru1, 30jjJl~ 18liJi C ~ \ oJ -tt1 A'O):A.: ~ ti. ~ ~.!itkO)~H]tJ;lcil *i~), $.l.vJ*litlfJ'Hi:ln~O):/ )v/-{-/-{ '/ :7 ilsa"* W,lilY)9} Ie oft 1 ;(O)/J\ ti ULHJ.!iX ~l ~ j]Jljt:t1IJs~~ ~1 ~ 0 rAJ T ~U~, L.., i- 0) tt!JJ;~ 0) ~t ,@'lfJlJt tJ{j.,IE ~ T I!;'J \~ 1l.x:J:.O);tt;.ii!itl i:- b -:J L. c c AAf&! L- -r ~'6 0 Ii, R. A. Oka. ]. - M. Mautsambot~. ]. Dinga L. ? L- t: / r 4'-0) =1(1) '7 O):m['I)~/V(;O)tfilliT Reasii, H. Massampou. M. A. Leonard. S. Blake, --<-r, 7<) /7/:1'1) '7?l::fi:.",;o-'7 / r:ll) M. Linfield, E. O. Vineberg. M. Attwater, r.nJ'tC '7c/ClmlL, illH~~~~nt::m['I)?--<·/ ~'-lf1 ~ ~ft, ~.~·Dch. ~/'ffffl~7-lfM!i.J:~ 0).~~$m.['I)~~6L.ci:-MmKL--r~~0 f-O)};~J.illO)ft~O)}j q. M. Fay, M. Hatchwelli: Up L- til):; i? Mitani (992) Ii, /' r 4'-0)::f' I) 'i t 51Ji+ /' ,<; /' S/ - O).J: ? 'C~i'J.~i:- L- -r~' 6 c c , 44 emigration and female transfer in wild mountain in the Dzanga-Sanga Reserve, Central African Repub gorilla. Nature, 263: 226 - 227. lic: Implications for population estimates and under Harcourt, A. H., 1978. Strategies of emigration and standings of group dynamics. Tropics, 4: 245 - 255. transfer by primates, with particular reference to Rogers, M. E., E. A. Williamson, C. E. G. Thtin and M. gorillas. Z. Tierpsychol., 48: 401 -420. Fernandez, 1988. Effects of the dry season on gorilla Harcourt, A. H., D. Fossey and J. Sabater-Pi, 1981. diet in Gabon. Primate Report, 22: 25 - 33. Demography of Gorilla gorilla. 1. Zool., Lond., 195: Sabater Pi, 1., 1977. Contribution to the study of alimen 215 - 233. tation of lowland gorillas in the natural state, in Rio IJlijj~BIJ, Hjt: ~, 1977. 71;/ ~ 7 ;/-t:7 Hl;Ic: Muni, Republic of Equatorial Guinea (west Africa). J:. Q \flJJHlti:Ei':t. ItI)!lYJ1:~'C;-':iiJfj'UEJ, pp.74 Primates, 18: 183 - 204. 85. -S-', i!fPJt, jlUf\o Schaller, G. B., 1963. The mountain gorilla: ecology and Jones, C. and 1. Sabater Pi, 1971. Comparative ecology behavior. The University of Chicago Press. of Gorilla gorilla (Savage and Wyman) and Pan Suzuki, S., T. Nishihara and S. Kuroda, 1993. Fruit troglodytes (Blumenbach) in Rio Muni, west Africa. dietary overlap between gorillas (Gorilla g. gorilla) Bibliotlleca Primatologica, 13: I- 96. and chimpanzees (Pan t. troglodytes) in the Ndoki Kawai, M. and H. Mizuhara, 1959. An ecological study Nouabale Reserve, Congo. Abstracts, 9th Annual on the wild mountain gorilla (Gorilla gorilla beringei). Meeting of the Primatological Society of Japan, Primates, 2: 1-42. Sendai (in Japanese). Kuroda, S., 1992. Ecological interspecies relationships Tutin, C. E. G. and M. Fernandez, 1984. Nationwide between gorillas and chimpanzees in the Ndoki census of gorilla (Gorilla g. gorilla) and chimpanzee Nouabale Reserve, northern Congo. In: Topics ill (pan t. troglodytes) population in Gabon. Am. J. Primatology Vol. 2, Bellavior, Ecology, and Conserva Primatol., 6: 313 - 336. tion, N. itoigawa, Y. Sugiyama, G. P. Sackett, and Tutin, C. E. G. and M. Fernandez, 1985. Foods consumed R. K. R. Thompson (ed.). University of Tokyo Press, by sY/l?palric populations of Gorilla g. gorilla and Pan Tokyo, pp. 385 - 394. t. troplodytes in Gobon: some preliminary data. Int. 1. :::'fr:m~. 19\)03. I:J;/ :JIR];j{-,' il'!l!J!Xoy1\UHtlCOJJl. Primatol., 6: 27-43. Tutin, C. E. G., M. Fernandez, M. E. Rogers and E. A. ~A:J r1\tlHtHiff·J.:J, 6: 18 ,- 29 0 Mitani, M., 199Gb. A note on the present situation of the Williamson, 1992. A preliminary analysis of the social structure of lowland gorillas in the Lope Reserve, primate fauna found from south-eastern Cameroon to Gabon. In: Topics in Primatology Vol. 2, Behavior, northern Congo. Primates, 31: 625 - 634. Ecology, and Conservation, N. Itoigawa, Y. Sugiyama, Mitani, M., 1992. Preliminary results of the studies on G. P. Sackett, and R. K. R. Thompson (ed.), Univer wild western lowland gorillas and other sympatric sity of Tokyo Press, Tokyo, pp. 245 - 266. diurnal primates in the Ndoki forest, northern Congo. Watts, D., 1984. Composition and variability of moun In: Topics in Primatology Vol. 2, Bellavior, Ecolog)\ tain gorilla diets in the central Virungas. Am. 1. and Conservation, N. itoigawa, Y. Sugiyama, G. P. Sackett, and R. K. R. Thompson (ed.). University of Primatol., 7: 323 - 356. Weber, A. W. and A. Vedder, 1983. Population dynamics Tokyo Press, Tokyo, pp. 215 - 224. of the Virunga gorillas: 1959-1978. Biological Con Mitani, M., 1. Yamagiwa, R. A. Oko, J.-M. Moutsambote, servation, 26: 341 - 366. T. Yumoto and T. Maruhashi, 1993. Approaches in Whitesides, G. H., J. E Oates, S. M. Green and R. P. density estimates and reconstruction of social groups Kluberdanz, 1988. Estimating primate densities from in a western lowland gorilla population in the Ndoki transects in a west African rain forest: a comparison of forest, northern Congo. Tropics, 4: 219 - 229. techniques, 1. Animal Ecology, 57: 345 - 367. Murnyak, D. F., 1981. Censusing the gorillas in Kahuzi Williamson, E. A., C. E. G. Thtin, and M. Fernandez, Biega National Park. Biological Conservation, 21: 1988. Western lowland gorillas feeding in streams and 163 -176. on savanna. Primate Report, 19: 29 - 34. Nishihara, T., 1992. A preliminary report on the feeding Williamson, E. A., 1988. Behavioural ecology of western habits of western lowlaml gorillas (Gorilla gorilla lowland gorillas in Gabon. Thesis submitted for the gorilla) in the Ndoki forest, northern Congo. In: degree of Ph.D, University of Stirling. Topics in PrimalOlogy Vol. 2, Behavior, Ecology, and Williamson, E. A., C. E. G. Tutin, M. E. Rogers and M. COllservation, N. ltoigawa, Y. Sugiyama, G. P. Sackett, Fernandez, 1990. Composition of the diet of lowland and R. K. R. Thompson (ed.), University of Tokyo gorillas at Lope in Gabon. Am. 1. Primatol., 21: Press, Tokyo, pp. 225 - 240. 265 - 277. Oates, J. F, 1978. Water-plant and soil consumption by Yamagiwa, J., 1983. Diachronic changes in two eastern Guereza monkeys (Colobus guereza): a relationship lowland gorilla groups (Gorilla gorilla graueri) in the with minerals and toxins in the diet? Biotropica, 10: Mt. Kahuzi Region, Zaire. Primates, 24: 174 -183. 241 - 253. IJJ~i~f-, 7o)tUf;Hh\lLt.!.0tL6tt!!t~& Remis, M. 1., 1993. Nesting behavior of lowland gorillas 1988. :J'I) IC-:>~ '1:" - ij -( )1/;/ fl*tlJtlH: tJ 7 :/UJO)}tf17'J' G r77 I) tJ liWt£J , 33: 19 -440 Yamagiwa, 1., N. Mwanza, T. Yumoto and T. Maruhashi, 1992. Travel distance and food habits of eastern lowland gorillas: a comparative analysis. In: Topics in Primatology Vol. 2, Behavior, Ecology, and Conserva tion, N. Itoigawa, Y. Sugiyama, G. P. Sackett, and R. K. R. Thompson (ed.), University of Tokyo Press, Tokyo, pp. 267 - 281. Yamagiwa, 1., N. Mwanza, A. Spangenberg, T. Maru hashi, T. Yumoto, A. Fischer and B. Steinhauer Burkart, 1993. A census of the eastern lowland gorillas Gorilla gorilla graueri in Kahuzi-Biega National Park with reference to mountain gorillas G. g. beringei in the Virunga region, Zaire. Biological Conservation, 64: 83-89. Yumolo, T., T. Maruhashi, J. Yamagiwa and N. Mwanza, 1989. Feeding habit of primates in the tropical forests of eastern Zaire. Grant-in-Aid for Overseas Scientific Research Report lnlerspecies Relationships of Pri mates in the Tropical and Montane Forests, I: 41-51.