Geochemical analysis of African buffalo geophagic sitesand dung on Mount Kenya, East Africa

by W.C . MAHANEY I and R .G .V . HANCOCK l

t Dg?qrtyeqt e"f Geog-r_aph.y,-Atkinson college, york (/niversity4700 Keele Street, North york, Ontario, eanada, M3J Ip3'

2 sLowP)KE Reoctor Facility and Departmenl

u n i,,l! i, f yf f : i "f fft' ffi': : f , ;' L,l ! :, l:,, o r,r,!f#,,' iili s r A 4

Summary. - Paleosols (ancient soils) and dung of African buffalo (Syncerus caffercaffer Sparrman) were analyzed for their elemental contents using neutron activation uni ly-sis in an attempt to discover possible st imuli for geophagic behaviour. The data indicaiethat the major elements Al and Fe are the most l ikely chemical st imuli for geophagicbehaviour. Sodium chloride and Ca do not appear to be involved in buffai-o miningbehaviour on the lower slopes of Mount Kenya. Chondrite-normalized rare earth elemenidistr ibutions show that the dung may be heavi ly laden with paleosol (up to 50 go) indicatingthat buffalo ingest relat ively large quanti t ies of paleosols.

Resumd. - L'analyse des paldosols (sols anciens) et des bouses de buff les d'Afr iquea permis de mettre en evidence le r6le jou6 par I 'aluminium et par le fer comme stimulantsles plus vraisemblables du comportement de geophagie. Le chloiure de sodium et Ie caleiumne paraissent pas €tre en cause dans le comportement des buff les qui creusent le solsur les contreforts du Mont Kenya. La proport ion de terres rares dans les bouses montrequ'el les sont fortement chargees de paleosols f iusqu'a 50 9o), ce qui montre que les buff lesen ingerent de grandes quanti tes.

INTRODUCTION

Over 24 months of Quaternary strat igraphic invest igat ions on Mount Kenya(Fig. l ) s ince 1976 | (WCM) observed, on a number of o icasions, Afr ican buffajo(Syncerus coffer caffir Sparrman) (Fig. 2) mining clods of reddish paleosol (ancientsoil) with their horns (Mahaney, 1987 a). This was followed by rather prolongedgeophagic activity (usually for I hr). In most cases mining sites were locatedin the montane forest consisting of Podocorpus milanjianus (elevations of2200-26ffi m). Less frequently, geophagic behaviour occurred in the bamboo forest-Hagenia woodland consisting of Arundinqria alpina and Hagenia obyssinica atelevations of 2800-3200 m (Coe 1967). Even though buffal6 frequently rangeacross the ericaceous and lower Afroalpine belts on the mountain (e.g. aboie3200 m) they do not mine sites at these higher elevations, possibly becauJe glacialdeposits date from the last glaciation and the soils formed in ihem ur. y-.oung,and hence, not highly weathered (Mahaney 1987a).

Marnrnalia, t. 54, n" l, 1990.

26 1\ IANlNIALIA

FIELD AREA AND METHODS

In an at tempt to study representat ive locat ions for mining act iv i ty and dungcol lect ing (Fig. l ) , we selected si tes at d i f ferent elevat ions bn Mount KenyalBuffalo mining si tes were sampled between 2300 and 2700 m on the western(TV70), southern (NYA2) and eastern (GOR75) f lanks of the mounrain (Fig. l ) .Sites for dung sampling were selected at different elevations from ZljO m to3000 m (GOR74 on eastern and TVT l and 72 on the western f lanks) to determinei f the relat ive concentrat ions of certain chemical e lements might vary as a funct ionof increased al t i tude.

The si tes (Fig. 3) favored for geophagic act iv i ty are always exposures ofreddish to reddish brown (7.5YR 4/4-5YR 4/4; see Oyama and Takehara 1970for soi l colors) paleosol (ancient soi l ) sect ions in road or stream cuts. Thesesoils are old and many are compound paleosols that have formed in transportedor residual regol i ths over the last mi l l ion years (Mahaney et a l . 1989). In general ,these si tes have high contents of < f ree > i ron and other l iberated oi ides.

Soi l nomenclature fo l lows the Soi l Survey Staf f (1975) and soi l colors werematched with the color plates of Oyama and Takehara (1970). Part ic le s ize deter-minat ions were made by dry s ieving the sands and calculat ing s i l t p lus c layfol lowing sedimentat ion of the < 63pm fract ions. Untreated simples^were ai idr ied and subsampled for neutron act ivat ion in the SLOWPOKE Reactor atthe Universi ty of Toronto using procedures developed by Hancock (1978). Laterthe samples were t reated with HzO2 to remove organic matter and with sodiumpyrophosphate to achieve def locculat ion pr ior to part ic le s ize analysis. A Bransoncel l d ismembrator was ut i l ized to disperse col lo ids pr ior to wet s ieving.

DISCUSSION

Laboratory analyses were completed on several paleosol and dung sampleswith the object ive of explaining buffalo geophagic behaviour.

Pqrticle Size.

The particle size distributions in all mining samples showed that clay ( < 2 pm)increased with depth reaching l8-88 percent in bur ied 82 hor izons (Soi l SurvevStaff l9l5). Most of these buried 82 horizons have silty loam to clay textureswhich are quite distinct from the silt loam textures in the overlying A horizons.Clearly the buffalo prefer these clay-and silty clay loam texture-iich materialsfor geophagic act iv i ty.

Geochemistry.

We analyzed all soil and dung samples by neutron activation which gavethe concentrat ions of 35 macro, micro and rare-earth elements. The chemicalparameters showing the greatest d i f ferences between soi l and dung are displayedin Tables I and 2. With regard to the buffalo mining si tes, Na, Cl und

-Ca

MAMMALIA P I . I

.WAw.WAw"rs"

'1

Fig.2. - Syncerus caffer caffer Sparrman on western flank of Mt. Kenva near site TV7l.

o 5 r o 2 0 5 0--##

0 5 r o 2 0 s o

Fig. 3. - Mining site GOR75, Mount Kenya Podocarpus Forest.

G E O P H A G Y O T ] S Y N C ' E R U S

TABLE l . - Geochemis t r y o f bu f fa lo m in ing s i tes on Moun t Kenya .

P a l e o s o l ( N Y A 2 ) : ( 2 3 0 0 E )

2',72',7

E lcenc

l 2

N e p p o { 7 0 5 8 0

C l p p o : 9 0 r 9 0

C r I 0 . I 0 0 . 0 5

F . I 8 . 2 l 7 . 9 0

l r p p o 3 . 9 4 . 3

I ppo 21 . l 8

5 6 1 2

9 2 0 r 0 l 0 1 5 6 0 1 8 3 0

< 9 0 r 1 6 0 < 2 1 0 r l 2 0

0 . I 0 0 . 0 / . 0 . 2 5 0 . I l

7 . I 0 7 . 8 0 r 3 . 9 l / i . 9

9 . 8 7 . 3 r 8 . 8 1 9 . 5

8 0 3 { 6 6 7 1

P . l c o s o l ( G o R 7 5 ) : ! 2 1 ! Q S )

I 2 J 4 )

6 0 8 6 2 2 6 0 0 1 1 0 0 0 1 3 9 0 0 I 1 2 0 0

I 2 1 0 { 4 9 0 t t 1 2 0 : l I 0 < t 2 0

t 0 . { r 0 . 3 9 r 0 . 4 1 . s 0 . 3 8 : 0 . 1 5

8 . 0 0 6 . ? 9 7 . 0 6 7 . 1 2 7 . 6 r

{ . 1 5 . 0 3 . { 6 . t 5 . 2

3 / .

6 7 0 8 2 0

r l 0 0 r 1 2 0

0 . 0 8 0 . 0 7

7 . \ 7 8 . 5 6

1 . 5 1 2 . 6

t 9 l 8

uJuJll))ggoouJuJNNJJ

tt

zz

tirtirtt

oozz

IIOO

La Ce

Fig. 4 . - Summary o f

COR75) re la t ive to

Nd Sm Eu Tb Dy

the e lementa l concent ra t ions o f the pa leosol (TV70 ; NYA2 ;the sur face pa leosol (TV6lA) .

Lu

28 M A M M A I , I A

are consistent wi th age and leaching condi t ions in the montane forest . TotalFe is wi th in the range for older paleosols (ancient soi ls) (Mahaney 1987b). Theelements Br and I , in general are s l ight ly higher at s i te NYA2 on the southernf lank of the mountain.

Analysis of the dung samples reveals some significant differences comparedwith the mining si tes. Na and Cl are general ly higher in the dung samples studied ;one buffalo dung sample has markedly higher amounts of Na and Fe (TV7l-4),which resul ts f rom paleosol consumption rather than from l icking precipi tatedsal ts on other buffaloes (Sinclair 1977 ; Mloszewski 1983). Overal l , Ca, Cl andBr are higher in the dung samples, and are probably derived from ingestedplant mater ia l .

Def ic iencies in Fe may provide a possible st imulus for roadcut mining bybuffalo as indicated by the t rends in Tables | & 2. In the mining si tes, Feranges from 7.1 to 14.9 percent, whereas the dung samples have < 1.0 percentin general . As discussed by Mahaney (1987a) Fe def ic iencies may provide a reaso-nable explanation for geophagic behavior. As buffalo are forced higher on themountain the need for erythrocytes in blood increases creating a need for Fe(St ickney and van Liere 1953). At e levat ions of 3000 m the erythrocyte countin humans is approximately l .4x that at2100 m (Matthews 1954). Buffalo geopha-gic behaviour at 2300 m may be compatible with Fe deficiencies in blood becausethe normal foraging height for the species is < 2000 m (Mloszewski and Mahaneyl 987) .

Because Br is general ly high in the dung samples (Table 2) relat ive ro themining si tes, i t is probable that buffalo on Mount Kenya f ind suf f ic ient bromidesin plant mater ia ls to sat isfy their d ietary requirements. Lower I in c lung relat iveto the mining si tes may signal a def ic iency that can only be met through geophagicact iv i ty. Once again dung sample TVTl-4 y ie lded signi f icant ly greater I and Fewhen compared with the other samples. One gets the impression that th is dungwas der ived from ei ther a s ick indiv idual or more probably f rom the f i rst re leaseof sediment f rom an indiv idual immediately af ter engaging in geophagic act iv i ty.However, a comparison of average elemental concentrat ions of the paleosol sam-ples wi th average values of e lemental concentrat ions in surface paleosol hor izonsof the region, as displayed in Table 3, changes the interpretat ion s igni f icant lyi f one addresses the problem using the element rat ios of bur ied paleosol /surfacepaleosol . The rat ios are shown in Figure 4 as an elemental grouping by high,even, and low combinat ions of the rat ios for the three geophagic s i tes.

For the elements Mg, Cl , Ni , and Ca, al l data sets are detect ion l imi tsso the rat ios are analyt ical ly useless in absolute terms. But, the low Cl concentra-t ions conf i rm the in i t ia l conclusions that we are not deal ing wi th a s imple NaClsource for the buffalo.

With a few anomal ies, the elements tend to be distr ibuted in a geochemical lysensible fashion. The major anomaly is Br which is highly enr iched in the surfacepaleosol re lat ive to the bur ied hor izons. Therefore, the bur ied paleosols are nota pr imary dietary source of Br. Na, K, Co, Mn, and Sr are qui te var iablewith no speci f ic t rends. These include the most chemical ly mobi le of the elementsstudied. A number of the remaining elements are s igni f icant ly enr iched in thethree bur ied paleosol sui tes relat ive to the surface paleosol including Al , Fe,Cs, Ce, Hf , Ta , Th , and U.

( ; E O P H A ( ; Y O F S Y N ( . I ] R L , S

IABLE 2' - Geochemistry of buf fa lo dung samples col lerr tcc l at d i f ferent e levat ions on Mount Kenya.

29

E l e o e n t l J e s c c a c e ( 2 1 5 0 o )----i-rTTzj-----i-rTTzj-

1 2 3 4 5

N a p p n 5 9 0 6 5 0 7 7 0 3 E 0 4 0 0

C l p p n 7 { 0 7 8 0 1 0 8 0 7 l O 5 Z O

C a I 0 . 5 8 1 . 3 6 0 . 9 1 0 . 4 9 l . 0 l

F e I 0 . 1 9 0 . 3 2 0 . 5 q 0 . 1 9 0 . 3 1

B r p p u 2 4 . 0 I I . 8 3 2 . O 1 9 . 5 3 4 . 8

I p p r s 4 s l O s 9 s 3 s 6

H e r S c a c i o n ( 3 0 0 0 o )---trwTt-- ---trwTt-- ----

L 2 3 t 1 5

2 5 7 6 4 0 l l 0 0 ( , 1 4 0 8 8 0

9 4 0 3 1 2 0 0 3 7 0 0 4 4 0 8 8 0

0 . 9 8 1 . 7 3 l . B 8 0 . 8 9 0 . 9 6

0 . 1 5 0 . 2 2 0 . 2 5 1 . 8 2 0 . 5 7

2 3 . 7 3 6 . 7 5 3 . 4 1 2 . 8 2 0 . 7

s 5 < 5 s 5 < l 1 9

C h o g o r i a R o u r - e ( 3 0 0 0 m )ffiffi

r 2 3 1 5

8 0 0 5 0 0 1 3 0 0 8 5 0 1 0 6 0

4 2 2 0 l I 8 0 1 5 6 0 1 2 0 s 5 0

0 . 8 7 0 - 7 5 0 . 8 5 0 . 4 5 I . \ 2

0 . 1 4 0 . I 0 0 . 2 3 0 . 2 1 0 . 2 8

2 3 . 4 r 0 . 6 2 4 . 6 5 . 3 9 . 0

t S s l , l 5 s \ s 4

tsUFFALO DUNG

3 r c o:):)))ssLIJLIJ

NNJJ

(Y(Y

44r,.lJr,.lJ

ttccccooZ t n

ooII

G0R74-5rvTt-3

rvn -4

rvTt-5

rv72- tr v72 -5

4 0 - 5 0 % p o l c o s o t

L UY bDyt r , ,t ^

Fig. 5 . - Chondr i te-normal izedrare ear th e lement d is t r ibut ions in buf fa lo min ing s i res.

30 M A N , I M A L I A

The bulk of the elements vary f rom even to highly enr iched in TV70 andGOR75 and from about even (given the scatter in the data) to highly enrichedin the NYA2 paleosol . This group includes the bulk of the rare earth elementsLa, Nd, Sm, Eu, Tb, Dy, Yb, and Lu along with Sc, Ti , V, Cr, As, Rb, Sb, and Ba.

I f the geophagic behaviour of the buffalo is chemistry related, then anyor al l of these elements could be important even though the biological l imi tat ionsof many are not wel l understood. I f major elements are most important in geopha-gia then Al (for upset stomachs?) and Fe are prime candidates for encouraginggeophagic behaviour.

Since, among the three paleosol sui tes of samples the elements do not varyconsistently, we are dealing with 3 different geochemical source materials ratherthan organic or sand- tempered var iants of the same basic mater ia l . Yet al l ,re lat ive to the topsoi l (surface paleosol) , are high in Al and Fe.

Rare earth element analyses.

Chondr i te-normal ized plots of the rare earth elements are displayed in Figure5 for the average values of TV70, NYA2, and GOR75 and for TV6IA surfacepaleosol. These show a reasonable similarity for average TV70 and GOR75 (although

there are large var iat ions as shown by the lack of precis ion of the data in Table3) and major di f ferences between them and the surface paleosol TV6IA andNYA2 with i ts large posi t ive Ce anomaly.

The chondr i te-normal ized REE plots for the buffalo dung are shown inFigure 6. Because of the very low levels of some of the rare earth elements,95 Vo confidence upper detection l imits have been plotted - with dotted l inesconnect ing them to << real >> data points. The curves for TVTI (samples 4,5and 3) and GOR75 have simi lar shapes and are s imi lar to their paleosols. TVTl- land 2 show the same cur ious low La as can be seen in the surface paleosol

TV6IA and may be related.From this data, i t is possible to make an est imate of the relat ive amounts

of paleosol in the buffalo dung. For example TVTl-4 appears to contain 40-50V0paleosol and TVTI-5 appears to contain 8-1090. The rest appear to contain3-5 9o of paleosol per buffalo dung sample.

CONCLUSIONS

Buffalo geophagic activity on Mount Kenya appears to occur at elevationsfrom 2100-3000 m as an act iv i ty carr ied out by lone indiv iduals (Mahaney 1987a).I t is a lways directed at reddish- brown paleosols (ancient soi ls formed undertwo or more di f ferent c l imates over long t ime spans, e.g. > 500,000 yr) . Buffaloalways appear to seek mater ia ls wi th high amounts of c lay (30-50 percent) . Ofal l the elements analyzed Fe and Al appear to provide the most important st imul ifor buffalo geophagic behaviour.

G E O P H A G Y O F S Y N C E R L J S

TABLE 3 . - Average e lemen t concen t ra t i ons in th ree m in ing s i tes (TV70 , NYA2, and GOR75)compared wi th a surface paleosol hor izon (Tv6lA) on Mount Kenya.

3 l

T V T O6 s a m p l e s

N a p p m 5 0 0 i 1 5 0M g ( Z ) . . 0 . 4A l ( z ) 1 4 . I r 0 . 6C I p p m s I l 0 t 3 0K ( 7 . ) 0 . 3 7 1 0 . 0 9C a ( 7 ) < 0 . 0 7 i 0 . 0 3S c p p m 1 3 . O i C . 5T i ( z ) 0 . 6 2 1 0 . 0 2V p p m 8 2 x 6C r p p m l 0 4 i l 5M n p p m 4 5 0 * 9 0F e t Z ) 8 . 6 1 0 . 4C o p p m 4 . 8 t 1 . IN i p p m 4 6 t 7

A s p p m 9 . 4 r L . 2B r p p m 7 . 6 t 3 . 3Rb ppm 5216S r p p m s 7 0S b p p m 0 . 6 7 r 0 . l 2C s p p m 4 . 8 1 0 . 8B a p p m 5 3 0 i 9 0L a p p m 2 4 0 r 4 0Ce ppm 260* .7 0N d p p m I 5 0 f 3 0S m p p m 2 4 t UE u p p m 3 . 8 i 0 . 7T b p p m 3 . 9 t 0 . 7D y p p * I 7 1 3Y b p p m l 4 i 3L u p p m 2 . 1 f 0 . 4H f p p m 2 3 t IT a p p m L 7 t 2T h p p m 2 8 t 3U p p r n l 6 t l

NYA22 s a m p l e s

1 5 2 0 r 3 5 0s 0 . 41 4 . 6 t 0 . 9s I 6 0 t 6 00 . 4 9 r 0 . 0 44 . 1 9 r 0 . 0 81 9 . 8 r 2 . 40 . 7 5 r 0 . 0 682+37 4t22 6 0 0 r 3 6 01 5 . 2 r 0 . 4I 3 . 1 1 0 . 3

? A + ' l

1 4 . 0 r 0 . 5I 9 . 2 + 0 . 5I 4 1 3s 7 00 . 6 0 r 0 . 0 64 . 0 r 0 . I2L0120I q + l

7 5 0 i 4 029+24 . 4 t 0 . 50 . 6 4 * 0 . l 40 . 7 9 r 0 . 0 22 . 8 * 0 . 53 . 0 r 0 . 20 . 5 3 * 0 . 0 24 9 r I3 9 i l6 l i I6 . 0 r 0 . b

G 0 R - 7 55 s a m p l e s

1 4 , 0 0 0 r 5 , 8 0 0< 0 . 8 r 0 . 21 3 . 6 1 0 . 9s 3 1 0 t I 4 0l . 7 r 0 . 6

s 0 . 3 5 t 0 . 0 8

5 . 0 1 0 . 60 . 3 9 1 0 . l 0< ' l | + , ?

s 2 4 * . 9

2 9 0 0 1 6 0 07 . 2 x 0 . 64 . 6 1 I . 3< ? o + ?

3 . 4 r 1 . 44 . 9 + 1 . I5 6 * 41 9 0 1 4 00 . 3 6 1 0 . l 4

2 . 8 i 1 . 31 0 8 0 r 2 7 0260* .2303 4 0 a 2 01 7 0 i 9 02 4 t L z3 . 6 r r . 23 . 4 * 2 . I1 5 . 3 r 8 . II I . 6 1 4 . 71 . 6 1 0 . 62t*.2I 8 T I) \ + )

5 . 0 r l . 3

TV 6 lr^? ^ ^ - - r ^ ^4 ) d u l P r E S

4 6 0 0 : . - 3 0 0< 0 . 56 . 7 t 0 . 4< 2 0 00 . 7 a 0 . I

< 0 . 35 . 0 * 0 . 20 . 3 8 r 0 . 0 232r84 l r 32 6 0 0 t 3 0 04 . 4 r 0 . ' 28 . 3 r 1 . 0

< { t l

4 , 2 t 0 . 39 5 1 54 6 r 3t 0 0 + 2 00 . 2 5 r 0 . r 02 . 0 r 0 . I3 5 0 r 5 042* .51 4 0 i 2 03 5 r 56 . 6 1 0 . 6l . 0 r 0 . l0 . 9 r 0 . 23 . 4 r 0 . 23 . 4 r 0 . 30 . 4 3 r 0 . 0 6I l r 1I I t I1 1 + )

3 . 7 r 0 . 4

PALEOSOL

SURFACE SOIL

l r l

t t lt l l

IIII

r l lTVTO NYA2 GOR75

N B ]

Al , Fe, Ce, Cs, Hf , Ta, Th, U

As , Ba , C r , Dy , Eu La , Lu , Nd ,Rb Sb, Sc Sm, Tb, Tr , V, yb

Co, K, Na, Sr

Mn

Br

PALEOSOL HIGHPALEOSOL ABOUT EVENPALEOSOL LOW

Fig.6 . - Chondr i te-normal ized rare ear th e lement d is t r ibut ions in buf fa lo dung samples.

3232 M A M M A L I A

ACKNOWLEDGEMENTS

This research was supported by grants from the Natural Sciences and Engineering

Research Counci l of Canada to WCM (Grant A9021) and to the Slowpoke Reactor Faci l i ty

of the University of Toronto. The inspirat ion for this research came from my constant

companion C. Mahaney. Linda Mahaney is thanked for assistance in the f ield. Field

work was authorized by the Off ice of the President, Geological Survey and Mountain

National Parks, Republic of Kenya. Laboratory analyses were completed in the Geomor-

phology and Pedology Laboratory at York University and the SLOWPOKE Reactor Faci l i ty

a t the Univers i tv o f Toronto.

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