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SINEr.Ethiop./. Sci.; 33(1):67-n,2010 . . College of Natural Sciences, AddisAb,aba University, 2010Shortconunurrlcatipn

ISSN: 0379-2897

A PRELIMINARY SURVEY OF ERYI1IROCEBUS PATAS IN ANB~SACHAKA,BAMBESI WOREDA OF ~ENISHANGUL-GUMU7REGION, WESTERN ETHIOPIA

Solomon Yirga 1, Man}ringerew Shenkut 1, Mezgebu Ashagrie 1 and Demissew Sertse 2

1 Department of Biology, Faculty of Science, Addis Ababa University, PO Box 1176,Add~ Ababa, Ethiopia. E-mail:solyirga@YahoQ.com

2 Holetta Agricultural ~earchCentre, PO Box 2003, Addis Ababal Ethiopia

ABSTRACT: A preliminary survey conducted in Benishangul-Gumuz Region, BambesiWoreda from late January to early February, 2010 resulted in finding two grc.>upsof the sametaxon of patas monkeys. Each of the two groups had one adult male, ana one of themconsisted of 33 individuals, where as the other had a total of 23 individuals including Theadult males, adult and sub-adult fe,males and infants. The survey was conducted on foot andby a vehicle and behavioural data were collected using adlibtum method. From the structureof the two groups and the season during which they probably had their newborns, theybelong to the species. Erythrocebus patas which are also found elsewhere. However, the longblack fur coloration along the shoulder, back and upper fore limbs of the males is differentfrom any o(the four different subspecies, namely, E. patas patas, E: patas villiersi, E.pataspyrrhonotus and E. tNltas baumstarki, arid others found in Athi plains, southeast of Nairobi andeast of the rift valley, which have pink f

Solomon Yirga et aL

~pq~d(gray long fur (C;loves,'1972; Ankel- walking andt running (Fleagle, 1999). They areSini6ns,20(7). . . extremeiy alert, fast runners (55 km/h) and they

Patascolour. tones and patterns and faciaf' frequently stand bipedally to lqolv over the tallcolorations vary considerably With localities .grass for potential predators or other interspe-(Napier and Napier, 1976~, Particularly, Hill cifie/intraspecific groups (Napier and Napier,(1966) and Dandelot (1971) grouped E; patm; in to 1976; Fleagle, 1999). .'four subspecies based on their faciaf coloration The diurnal activity pattern of patas monkeys.and geographic distribution. These four subspe- is comprised of two main feeding periods with ades are E. p. patas, E. P. villiersi, E. p. pyrrhonotus rest period of one. to' three. hours in. the hottestand E. :p. bal,lmstark{ E. p. patas is geographieally time of the day (Hall, 1966). Both the daily traveldIstributed in western savannah from Senegal to distance and the home range size are greater inChad. and is morphologically' characterized by patas than other cercopithecid monkeys.This canpale pink face and black nasal spqt. E. P. villiersi be attributed to its higher preference for grass-occur f~om Air (Asben) massif in the Sahara to land with low habitat quality in the case of patasnorth of the bend of the Niger River and shares (Nakagawa, 1999). Day ranges of patas aTemorphological sjmilarities with E. p. patas but it extraordinarily variable from grou'p to group anddiffers by its small size. E.p. pyrrhonotus is found from season to season, ranging from 700m tofrom Cameroon through southern Sudan and nearly 12,000 m. Sometimes the group forageswestern Ethiopia to localized areas of Kenya, cohesively and other times members of a groupnorthern Uganda and Tanzania. ThiS subspecies are separated by as much as 800m (Fleagle, 1999;is characterized by blackish face and adults Hall, 1966). The estimated home ranges are overdevelop a white nasal spot anq there is also a 5,000 ha, which is th.e largest" i

SINET: Ethiop. 1. Sci.; 33(1); 201,OIShort eo~unication]

Otherwise females will harass the male if it is too .close (Hall, 1966).

Timing of reproduction seems to varysomewhat with geography. In most populations.mating takes place in June through September,and babies are born between November andJanuary (Bonadio, 2000). The patas monkeys(Erythrocebus patas) mostly give birth in the dryseasOn' as opposed to guenons (Nakagawa, 2000;Struhasker and Gartlan, 1970).

Patas monkeys are adapted to ground livtngand open country (Ankel-Simons, 2007). They arewidely distributed in semidesert, savannahgrassland and woodland i'om Senegal toWestern borders' of Ethiopia, north to Nubia andsouth to Serengeti and Athi plain and west sideof mount Kilimanjaro, Air and Ennedi (Groves,2001). In .Ethiopia, the range of geographicdistribu;tion of patas monkey is foundsporadic'llly along the western border indeciduous savanna-woodland of North West(around Meteinma)' to west (Guba (in theprevious western Gojjarn/ the present Benishan-gul-Gumuz Region), Gambela region (formerlyin Illubabor) south of Gilo River and AkoboRiver) and south to the northern limit of the OmoNational park and eastern part of the Omo River(Bolton, 1973; Yalden 'et aI., 1977). The altitudinalrcing~ of this patas monkey does not appear toextend much above 1000m and mostl it is 500-

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1000 m (Bolton, 1973; Yalden ~t.aI.; 1977; :VaIdenet aI., 1996).

Prior to this research work, no systematic fielddata have been available. on the populationstatus, human-patas interaction, behaviour andecology of the Ethiopian E piltas other than thegeographic distribution surveys of the seventies.

The purpose of this preliminary survey was tosearch for and locate E patas piimarilyto:

1. determine the presence of E. patas at thestudy area;

2. gather preliminary information on theirsocial organization, ecology,. behaviour andmorphological features.

Study areaThe study area 'is located in western Ethiopia,

Bambesi .district, Assosa Zone of Benishangul-Gumuz National Regional State (Fig. 1). It isaround 624 km to 639 km from Addis Ababa. Therange of the study area consists of mosaic ofbamboo forest, woodland, riverine forest and.cultivated lands. 'Within these habitats Sorghum,Syzygium spp. and Ficus spp.have been observedfrequently apart from varieties of woody plantspecies. In addition to its.flora, different primatefauna like patas, grivet monkeys, olive baboons

.and Colobus guereza are dwelling in the studyarea.

;;"",,-.-;,.................~...........:;........

[] ECreglon.shp .

70

MethodSurveys for Patas were conducted in Anbesa'

Chaka, Bambesi woreda, Benishangul-Gumuz.(late Janmiry-early February 2010). DUi'ing thesesurveys a total of 28 hours were spent watchingE. patas. Surveys were undertaken on foot andusing a slow moving vehicle.

During the survey, the main road from Babesidistrict to Assosa was used as the main surveyroute. In addition to this main route, in thelocality between Anbesa Chaka and Gara-biche/Songa, three survey routes to the right ahdleft sides along the main road were used. At thetime of survey when E. patas were encountereddata on their location, mOrphology, group size,social structure and behaviour were recordedthrough direct observation. Their location was re-corded using Global Positioning System. Groupsize was determined by simple GOunting. Socialstructure such as age and sex were determined'based on their morphology, size and colorationthrough direct observation: The behavioural datawere collected through adlibetum method(Altman, 1974; Lehner, 1996).

RESULTS AND DISCUSSION

In the survey conducted, two groups wereobserved in a range between Anbesa Chaka andGarabiche/Songa. The first and second groupswere encountered at almost the same time at948.5'N and 3442.6'E in agricultural landsaround Garabiche/Songa woodlands and at953.76' and 3440.27' in the bamboo forest alongthe main road to Assosa and its adjacent cultiva-tion sites, respectively. The two groups wereobserved betWeen 624 km and 637 km fromAddis Ababa to Assosa or 23 km to 36 km fromAssosa.

Usually, patas monkeys' social structures haveone-male and all male groups (Napier andNapier, 1976), but the two groUps observed inthis survey were one-male groups. The size of thefirst group was 23 and that of the second was 33.In both groups, most adult "females carried theirinfants ventrally. This revealed that their birth

Solomon Yirga et al.

bearing season is most likely during the dryseason until the end of January.. This period. issimilar to the patas studied'. elsewhere (Stru-hasker and Gartlan, 1970). As they are dwellingoutside natural reserve' area~, they are prone tothe danger of human presence arid activities.However, the fact that they are able to survive insuch an area in good numbers shows that thehabitat quality is better compared to studiesconducted elsewhere (Hall, 1966; Struhasker andGartlan, 1970).

Behaviourally, the patas monkeys are fastrunners and silent: During a half-day continuousfollow-up,. no vocalization was detected. Thus, intheir communication, visual signals such as bodypostures and facial expressions might play im-portant roles. Normally, group movement was.

. led by a dominant female while the groups' adultmale usually takes its peripheral position at theback. The male frequently climbed a tree andwatched the. surrounding. When he detected anythreat he swiftly runaway into the group andtook the leading position:

As the time ofsurvey was sorghum harvestingseason, patas mon~eys were mostly observedfeeding in the sorghum harvesting sites. Patasmonkeys are crop pests for the local crop

harv~sting people; hence the' monkeys areusually chased whenever they are encountered.Perhaps, as a result of this, the patas monkeys aresilent and tried to disguise themselves in trees.

Morphologically, patas monkeys observed arehighly sexually dimorphic, both in their size andcolour. As in other patas subspecies (Groves,2001), the adult male is brighter and bigger thanadult females. Both adult male and' females haveblack face with white moustache, reddish-brownhead crown, brownish-white neck, blackline/ strip on t~mporal suture/lines and whitishventral parts. Besides these common features, themale is characterized by white beard, whitecheek tutt, gray forelimb and chest, long dark-gray/black fur back. on the shoulder towardsupper arm, brown on the back (thorax to tail),dark-brown tail, blue. scrotum and whi~eposterior hind limbs (Fig. 2). However, dorsalparts of the females are tan.

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SINET: Ethiop. 1. Sci., 33(1), 2010 [Short communication] 71

Fig. 2. Back and front views of adult male patas monkey (Erythrocebus patas) of the study group.

CONCLUSION

Some features of the adult male, especially thelong dark-gray/black fur on its back shoulderthat extends to upper forelimbs, distinguishpatas monkey i.I1 the study site from other patasmonkeys described so far. There is, therefore, apossibility that patas described in this studycould be considered as potential new subspecies.The survey ,conducted 'in and around AnbesaChaka is also the first investigation to reveal thepresence of patas monkey in this part of Ethiopia.Though our preliminary survey showed a dis-tinct morphological feature/ coloration, and st-ructure of the groups observed, further morpho-logical, behavioural and molecular studiesshould be conducted to arrive at a: definiteconclusion on the taxonomic status of the group.

ACKNOWLEDGEMENT

We thank Addis Ababa University School of GraduateStudies and Research and Professor John Kapplemanfor financial support for this study. We also thankBambesiWoreda Administration for permission toconduct the survey"and the anonymous reviewers fortheir constructive comments.

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