The objective of this study was to determine the density and habitat preference of the Black-andrufous elephant-shrew (Rhynchocyon petersi) in Chome Forest Reserve, Tanzania. Chome Forest (143km2) is located in the South Pare Mountains and provides critical habitat for endangered R. petersi. Twelve 300m transects were cut through the centre of the forest in an east-west direction and the number of elephant-shrew nests within 2.5 meters on each side of the transects was recorded. The mean number of nests per 100m transect (0.39 ± 0.47 [1SE]) translated to a density estimate of 19 elephant-shrews per km2 (SE=23). Nest sites tended to be found in areas with greater than expected cover at the low (R. petersi is lower in the Chome Forest Reserve than in most populations in the Eastern Arc Mountains. The reasons for this difference and the conservation implications are discussed

Coster, Stephanie

Ribble, David O

English

Trinity University

Trinity UniversityDigital Commons @ TrinityBiology Faculty Research Biology Department2005Density and Cover Preferences of Black-And-Rufous Elephant-Shrews (Rhynchocyon petersi) inChome Forest Reserve, TanzaniaStephanie CosterTrinity UniversityDavid O. RibbleTrinity University, dribble@trinity.eduFollow this and additional works at: https://digitalcommons.trinity.edu/bio_facultyPart of the Biology CommonsThis Article is brought to you for free and open access by the Biology Department at Digital Commons @ Trinity. It has been accepted for inclusion inBiology Faculty Research by an authorized administrator of Digital Commons @ Trinity. For more information, please contact jcostanz@trinity.edu.Repository CitationCoster, S., and D.O. Ribble. (2005). Density and cover preferences of black-and-rufous elephant-shrews (Rhynchocyon petersi) inChome Forest Reserve, Tanzania. Belgian Journal of Zoology, 135(supplement), 175-177.Belg. J. Zool., 135 (supplement) : 175-177 December 2005Density and cover preferences of Black-and-rufouselephant-shrews (Rhynchocyon petersi) in Chome ForestReserve, TanzaniaStephanie Coster and David O. RibbleDepartment of Biology, Trinity University, One Trinity Place, San Antonio, TX 78212Corresponding author : David O. Ribble, e-mail address : dribble@trinity.eduABSTRACT. The objective of this study was to determine the density and habitat preference of the Black-and-rufous elephant-shrew (Rhynchocyon petersi) in Chome Forest Reserve, Tanzania. Chome Forest (143km2) islocated in the South Pare Mountains and provides critical habitat for endangered R. petersi. Twelve 300m transectswere cut through the centre of the forest in an east-west direction and the number of elephant-shrew nests within 2.5meters on each side of the transects was recorded. The mean number of nests per 100m transect (0.39 ± 0.47 [1SE])translated to a density estimate of 19 elephant-shrews per km2 (SE=23). Nest sites tended to be found in areas withgreater than expected cover at the low (<5m) levels. These results indicate the population density of R. petersi islower in the Chome Forest Reserve than in most populations in the Eastern Arc Mountains. The reasons for this dif-ference and the conservation implications are discussed.KEY WORDS : elephant-shrew, sengi, conservation, density.INTRODUCTIONAfrica’s tropical forests are home to large diversity ofspecies, many of which are endemic to the African conti-nent. With increases in both human population and defor-estation, more and more animals are becoming threatened(MYERS, 1988). The elephant-shrews or sengis (orderMacroscelidea) are one such group. There are 15 speciesin this strictly African mammal group, three of which arereferred to as “giant” elephant-shrews and are of thegenus Rhynchocyon (Peters 1847). All three Rhynchocyonspecies are considered threatened due to habitat destruc-tion and fragmentation, including the species that is thefocus of this study, the Black-and-rufous elephant-shrew(R. petersi, Bocage 1880) (NICOLL & RATHBUN, 1990).The giant elephant-shrews share similar life histories inthat they are diurnal insectivores that live in lowland andmontane forests and dense woodlands (RATHBUN, 1984).They can be found in altitudes ranging from sea level-2300m. While foraging they use their long proboscis toturn over leaf litter and dig up beetles, termites, otherinsects and centipedes. Once the arthropods are exposed,the sengi’s long tongue extends and scoops them up(KINGDON, 1997).For shelter, the giant elephant-shrews build nests. Thedimensions of their shelters are typically one meter widewith a body-sized bowl of 20cm long, 15cm wide and10cm deep (RATHBUN, 1979). Giant elephant-shrews livein monogamous pairs with defined territories and there-fore each animal can make and maintain up to ten nests inone territory with several nests in use at one time (FITZ-GIBBON & RATHBUN, 1994). Their territories are typicallyabout 1-1.7 hectare (RATHBUN, 1979). Because of theirdependence on undisturbed forest and their large territo-ries, their presence is an indication of a healthy forest eco-system.Of the giant elephant-shrews, the most is known aboutthe Golden-rumped elephant-shrew (R. chrysopygus) andthere are few records about R. petersi. The objective ofthis study was to estimate the density of elephant-shrewsbased on nest counts and analyze habitat preferences in anundisturbed forest reserve where R. petersi were knownto occur (STANLEY et al., 1996).MATERIALS & METHODSChome Forest Reserve is located within the EasternArc Mountains (37o 58’ 0.12” E, 4o 17’ 60” S), a range onthe southeast coast of Kenya and the eastern coast of Tan-zania. Chome Forest is made up of mostly wet montaneforests (submontane, montane, and upper montane) withelfin forest on high ridges and heathlands on rocky, acidicsoils. It covers approximately 142.8km2 and is situated onthe ridges and plateau of the South Pare Mountains in thedistrict of Same in Kilimanjaro Region, Tanzania. Thereserve was established in 1951 under the National ForestPolicy and Draft Act to ensure ecosystem stabilitythrough conservation of forest biodiversity, water catch-ment and soil fertility. Because of the high annual rainfalland pristine forest cover, the forest has a high watercatchment value and is an important resource for the 22surrounding villages in the catchment area. The altitude inthe reserve ranges from 1250-2400m. The estimatedannual rainfall is 1400mm. During the dry season fire is aproblem because it replaces dry and lower forests withheath land. Historically fire was not a threat but fires haveincreased with human activity near the forest. STANLEY etal. (1996) noted the presence of R. petersi in the ChomeStephanie Coster and David O. Ribble176Forest, but no study has documented the densities of theseelephant-shrews in this forest.This study was conducted in the rainy season betweenApril 11th and 29th 2001. Chome Forest is accessible byroad, but the forest itself is navigated only by footpaths.One such trail that is heavily trafficked bisects the middleof the forest from a west to east direction and is used bylocals trekking from Mhero to Kanza or Mhero to Bombo.Because the path was established and because there hadbeen sengi sightings in the area, this trail was chosen to bea reference path for transects. In order to estimate ele-phant-shrew density and habitat preference, transectswere cut through the forest starting from the forest edgeon the western side (near Mhero boundary). Twelvetransects were cut perpendicular from the path, each300m long and paced 500m apart. The first transect was500m from the forest edge.Nest frequencies within 2.5 meters on each side of thetransect were tallied. Both newer (in use) and older nestswere recorded. For more qualitative data, the number ofscraping/digging sites was also tallied. Using a densityconversion factor from FITZGIBBON & RATHBUN (1994)study on R. chrysopygus, the population density per km2was estimated.To examine if giant elephant-shrews were selectingspecific shade classes for their nests, percent canopycover was estimated every 20m along each transect ateach of three layers of canopy : < 5m, 5-15m, and > 15m.Percent canopy cover was divided into four shade classes,of 0-15%, 16-35%, 36-55% and >56%. Canopy cover wasalso recorded at each observed nest site and compared toavailable cover with χ2 analysis.RESULTSThe average number of nests found per 100m oftransect was 0.39 (SE= 0.47). Using the density conver-sion factor from the FITZGIBBON & RATHBUN (1994)study, the estimated density was 19 per km2 (SE=23). Byextrapolation a liberal estimate for the whole reservewould be approximately 2700 R. petersi.There was no evidence that elephant-shrews wereselecting specific shade classes in the middle or uppercanopy layers (P > 0.10). However, in the lowest canopylayer (< 5m) elephant-shrews selected higher shadeclasses for nests than expected (χ2 = 8.14, d.f.= 2, P <0.05; Fig. 1). In particular the shade class of 36-55% washigher than expected (Fig. 1).DISCUSSIONThe estimated population of R. petersi in Chome Forestwas 19 (SE=23) elephant-shrews per km2. This estimateis most interesting when compared to density estimates ofR. petersi from other forest reserves in the Eastern ArcMountains. HANNA & ANDERSON (1994) estimated popu-lation density of R. petersi for seven study sites in theEastern Arc Mountain range using similar techniques tothis study (Table 1). The population density of ChomeForest Reserve is low when compared to these other siteswhere R. petersi was found. According to HANNA &ANDERSON (1994), the available habitat for R. petersitends to be fragmented given its location at higher eleva-tions, which is typically on isolated mountains. Currentlogging and hunting pressures on these forests have fur-ther exacerbated the lack of habitable areas for R. petersi.Though Chome Forest is closed to timber harvesting andhunting, pit saws and traps were sighted in the forest andtherefore human activity in the forest could be limitingthe numbers of R. petersi. Also because of the proximityof the village and the lack of a buffer zone, the forest isisolated which could prevent immigration into the exist-ing population. FITZGIBBON (1994) suggested that for R.chrysopygus in Kenya, selective tree felling and pole cut-ting in protected areas have little effect on elephant-shrewdensities but she warns that in unprotected areas, humanpressure may be more of a threat.Rhynchocyon petersi chose nesting sites in areas ofgreater canopy cover than expected (Fig. 1), probably toavoid predators and to find sufficient leaf litter to con-struct nests. Nests were observed frequently at the base oftrees, and typically wild coffee was the predominantshrub of the understory. Scraping and digging sites wereoften found near coarse woody debris perhaps due to thehigher proportion of prey found living in this substrate.Finally, the forest edge seemed to have more nests (aver-01020304050607080901000-15 16-35 36-55 >56Shade Class (%)Percentage of total Habitat AvailableNest SitesFig. 1. – Shade classes for nest sites of Rhynchocyon petersicompared to the available habitat data collected every 20m.TABLE 1Estimated population densities of Rhynchocyon petersi in forestsites throughout Eastern Tanzania (from HANNAH & ANDERSON,1994).Forest site areas Area (km2)Population density in pristine areas of forest reserve (No./ km2)PuguKazimzumbwiRuvuKionoKisijuKwamkoroKiwandaChome – This study112998202UnknownUnknown14379.367.142.742.70 > 0 * > 0 *19.0* Not enough animals were captured for a density estimate, although a few animals were observed.Status of Black-and-rufous elephant-shrew 177age of 2.7 nests/100m) than the other areas of the forest(0.3 nests/ 100m), indicating the Black-and-rufous ele-phant-shrew may perhaps forage in both the forest as wellas in the surrounding heathland.The population density conversion factor we used wasdetermined from data collected on R. chrysopygus (FITZ-GIBBON & RATHBUN, 1994). HANNA & ANDERSON (1994)argued that R. petersi exist at lower densities than R.chrysopygus. If this is the case, then the conversion esti-mator results in a liberal density estimate for R. petersi.When extrapolating the population estimate for the entireforest, we assumed that the whole forest area providedadequate habitat for R. petersi, but there is evidence ofdisturbed areas of the forest which include burnings andheathland habitat which has not been known to supportelephant-shrew nests. All of these surveys of R. petersiwere conducted over short periods of time and ideallylonger studies should be conducted. However, in generalRhynchocyon populations do not vary substantially overtime (RATHBUN, 1979) so we are confident in our relativecomparisons between forests.The results of this study indicate that the population ofR. petersi in Chome Forest Reserve is low and isolatedwhen compared to other populations in the Eastern ArcMountains and thus long term conservation plans mustsafeguard the future of the forest. This study also showedthat forest cover is essential to the elephant-shrew, pre-sumably to avoid predation, while leaf litter is crucial fornesting materials. With the proposed community conser-vation agreement and the re-opening of the forest toselective timber harvesting, the elephant-shrew popula-tion should be closely monitored.ACKNOWLEDGEMENTSThe senior author of this study completed the project underthe guidance of the School for International Training (SIT) withfurther help from Jo Anderson. We would like to thank theauthorities at Chome Forest Reserve for granting access. TheDepartment of Biology at Trinity supported our travel to the 9thInternational African Small Mammal Symposium, Sokaine Uni-versity of Agriculture, Tanzania, where we first presented theseresults and we are grateful for that support. We would lastly liketo thank Galen Rathbun for his continued help and encourage-ment in our studies of sengis.REFERENCESFITZGIBBON, C.D. (1994). The distribution and abundance of thegolden-rumped elephant- shrew Rhynchocyon chrysopygusin Kenyan coastal forests. Biological Conservation, 67 :153-160.FITZGIBBON, C.D. & G.B. RATHBUN (1994). Surveying Rhyn-chocyon elephant-shrews in tropical forest. African Journalof Ecology, 32 : 50-57.KINGDON, J. (1997). The Kingdon Field Guide to African Mam-mals. Academic Press. San Diego, CA : 142-152.HANNA, N. & J. ANDERSON (1994). Njule 92, Final Report,assessing the status and distribution of the black-and-rufouselephant-shrew. Unpublished report. Oxford Universityexpedition to Tanzania. Oxford, England : 67pp.MYERS, N. (1988). Tropical Forests and their Species : Going,going, …? In : WILSON (ed), Biodiversity. National AcademyPress. Washington DC : 28-35.NICOLL, M. & G. RATHBUN (1990). African Insectivora and Ele-phant-shrews : an action plan for their conservation. IUCN,Gland.RATHBUN, G.B. (1979). The social structure and ecology of ele-phant-shrews. Advances in Ethology, Supplement to Journalof Comparative Ethology, 20 : 1-77.RATHBUN, G. (1984). Elephant-shrews, Order Macroscelidea.In : MACDONALD (ed), The Encyclopedia of Mammals. Factson File Publications, New York : 730-735.StANLEY, W., S.M. GOODMAN & R. HUTTERER (1996). Notes onthe insectivores and elephant shrews of the Chome Forest,South Pare Mountains, Tanzania. Zoologische Abhandlun-gen, 49 8 : 132-147.

Density and Cover Preferences of Black-And-Rufous Elephant-Shrews (\u3cem\u3eRhynchocyon petersi\u3c/em\u3e) in Chome Forest Reserve, Tanzania

https://digitalcommons.trinity.edu/cgi/viewcontent.cgi?article=1012&amp;context=bio_faculty

Density and Cover Preferences of Black-And-Rufous Elephant-Shrews (\u3cem\u3eRhynchocyon petersi\u3c/em\u3e) in Chome Forest Reserve, Tanzania

Abstract

Similar works

Full text

Available Versions

Trinity University