Exploring the Main Threats to the Threatened African Spurred Tortoise Centrochelys Sulcata in the West African Sahel

Exploring the main threats to the threatened African spurred tortoise Centrochelys sulcata in the West African Sahel

F ABIO P ETROZZI,EDEM A. ENIANG,GODFREY C. AKANI,NIOKING A MADI E MMANUEL M. HEMA,TOMAS D IAGNE,GABRIEL H OINSOUDÉ S EGNIAGBETO L AURENT C HIRIO,GIOVANNI A MORI and L UCA L UISELLI

Abstract The African spurred tortoise Centrochelys sulcata Keywords CITES, conservation, pet trade, Sahel, spurred is the second largest terrestrial turtle, with a scattered distri- tortoise, tortoise–livestock competition, transhumant graz- bution across the West African Sahel. This species is threa- ing system, wildfires tened and declining consistently throughout its range, but The supplementary material for this article can be found on- little is known about the causes of its decline. It has been hy- line at https://doi.org/./S pothesized that the decline is attributable to () competition with domestic cattle, () wildfire, and () the international pet trade. We conducted a series of analyses to investigate   these three causes. Hypotheses and were analysed Introduction using a spatially explicit approach, using a database of the Food and Agriculture Organization of the United Nations he African spurred tortoise Centrochelys sulcata and logistic regression modelling; hypothesis  was tested T(Plate ) is a native species of the Sahara Desert and by analysing the CITES trade database for –.We the Sahel, where its distribution is fragmented (Trape found a significant negative correlation between intensity et al., ; Petrozzi et al., , ). All populations of − of grazing (expressed as density of cattle, km ) and the this large tortoise (up to  kg weight) are reported to be de- presence of spurred tortoises, and this negative effect in- clining, mainly as a result of two independent threats: com- creased when coupled with high fire intensity, whereas wild- petition with domestic livestock for food and space (Branch, fires alone did not have a significant influence on the ), and collection for the pet trade (CITES, ) and for species’ distribution at the global scale. There was a decrease subsistence (Branch, ). The species is categorized as in the annual export of wild individuals for the pet trade Vulnerable on the IUCN Red List (Tortoise & Freshwater after the introduction of export quotas by country and by Turtle Specialist Group, ). year, but trade data must be considered with caution. The hypothesis that cattle are negatively affecting the tortoise’s status and distribution had not been tested previously but is theoretically valid because of the characteristics of the Sahel ecosystem where the species occurs. The Sahel is a transitional ecoregion of semi-arid grasslands, savannahs

FABIO PETROZZI*, GODFREY C. AKANI,NIOKING AMADI and LUCA LUISELLI† and thorn shrublands across Burkina Faso, the Central (Corresponding author) Department of Applied and Environmental Biology, African Republic, Chad, Eritrea, Ethiopia, Mali, Rivers State University of Science and Technology, Port Harcourt, Nigeria E-mail [email protected] Mauritania, Niger, Nigeria, Senegal and Sudan (Trape et al., ; Mallon et al., ). In the Sahel, which includes EDEM A. ENIANG Department of Forestry and Natural Environmental Management, Faculty of Agriculture, University of Uyo, Akwa Ibom State, several of the world’s economically poorest regions, most Nigeria people rely on cattle grazing and derivate activities to sur- EMMANUEL M. HEMA Université Ouaga 1 Professeur Joseph Ki ZERBO/CUP-D, vive (Touré et al., ; Barry et al., ; Kagoné, ). laboratoire de Biologie et Ecologie Animales, Ouagadougou, Burkina Faso Two main types of grazing systems tend to coexist in coun- TOMAS DIAGNE African Chelonian Institute, Ngaparou-Mbour, Senegal tries of Sahelian Africa: traditional extensive systems and GABRIEL HOINSOUDÉ SEGNIAGBETO Department of Zoology, Faculty of Sciences, modern, semi-intensive to intensive ones (Kagoné, ). University of Lomé, Togo Traditional systems are low-input systems, with no supple- LAURENT CHIRIO Grasse, France mented food or chemicals being used except during emer- GIOVANNI AMORI National Research Council (CNR) Institute of Ecosystem gency periods when forage availability is scarce. They Studies, Rome, Italy include the transhumant Fulani system (c. % of total cattle *Also at: Ecologia Applicata Italia srl, Rome, Italy stock), sedentary village stock-raising, and stock rearing in †Also at: IDECC–Institute for Development, Ecology, Conservation and Cooperation, via G. Tomasi di Lampedusa 33, I-00144 Rome, Italy developed pastoral areas. In the Fulani system, herds may be Received  June . Revision requested  July . single-species (Sudanian Fulani zebu) or mixed, with small Accepted  September . First published online  January . ruminants and cattle, and cattle are fed by opportunistic

Oryx, 2018, 52(3), 544–551 © 2017 Fauna & Flora International doi:10.1017/S0030605316001125 Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.93, on 30 Sep 2021 at 14:53:16, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605316001125 Threats to the Sahel tortoise 545

were poor and were not considered in the analysis, although spurred tortoises do occur in these countries (Largen & Spawls, ). From these data we deleted records of specimens that were not observed directly in the wild, as indicated in Petrozzi et al. (, ), or from areas where the species is now extinct (e.g. Cameroon; Chirio & LeBreton, ). For each presence point we used the longitude and latitude graticule used by Trape et al. (), in which each grid cell  was , km ( ×  km), in QGIS .. (QGIS Development Team, ). We deleted grid cells with . % of the area covered by sea, leaving  cells (n = ). Using QGIS we drew a minimum convex polygon inclu- ‘ ’ PLATE 1 An adult Centrochelys sulcata in the W National Park, sive of all presence points (n = ). Within this we created  Niger, West Africa. Photograph by B. Cornelis. random absence points, using QGIS functions (Fig. b). When randomly selected absence grid cells coincided with exploitation of forage resources according to a yearly se- presence cells the cells were replaced with new, random ab- quence of grazing involving five seasons and the various sence cells. Square grid cells (Trape et al., ) were used for types of pasture available (Barry et al., ; Kagoné, both the presence and absence points. ). Both this system and modern intensive grazing are Livestock density distribution data were extrapolated invasive for the natural vegetation of the Sahel and, as a con- from Robinson et al. (). We clipped a raster of cattle sequence, large areas have been altered (Kagoné, ) and density (Robinson et al., ) with a shape file covering many species are threatened (Mallon et al., ). the whole of the species’ range, in which both presence Sahelian pastoralists burn wide areas to facilitate cattle and absence grid cells were included (Fig. c). We then re- grazing, and fires also spread naturally throughout the classified the resulting raster file using the FAO format, with Sahelian region (Behnke, ; Smet & Ward, ; eight classes of density for livestock, yielding eight raster Solomon et al., ). It is predicted that the spread of files. These were transformed into shape files, which were fires may have a negative effect on the distribution of then merged into a single shape file. This was clipped for spurred tortoises throughout the region. each presence and absence grid cell. The hypothesis that the international pet trade may be a All the shape files (classified shape files, merged shape factor in the depletion of spurred tortoise populations had file, and presence and absence grid cells with cattle density) not previously been analysed in depth, as it is difficult to were processed using SpatiaLite v. .. (Furieri, )to test with field data. Nonetheless, CITES data are available correct potential invalid geometries, thus obtaining an out- and may provide some insight into potential conservation put file (.sql) for each grid cell. The .sql files were imported issues. into QGIS and saved as a new shape file to obtain the surface Our aims were () to explore the tortoise–livestock com- of all the classes, both for each grid cell and in total. From petition hypothesis by evaluating whether the distribution the surface of each livestock class in each grid cell we calcu- of spurred tortoises is negatively correlated with the density lated the percentage of cell territory covered by the various of domestic livestock, () to analyse whether there is an ap- classes of livestock density. Eight classes of livestock density parent effect of the spatial distribution of fires on the distri- were used, as also used by FAO. Classes of predicted live-  bution of tortoises, and () to analyse the CITES database to stock density (expressed as number of animals per km ), identify general patterns in the international trade of as obtained from the FAO dataset (FAO, ) and used Centrochelys sulcata. in our analyses, were: –; –; –; –; –; –; –; . .

Methods Fire analysis

Data sources and geographical information system (GIS) The distribution of fire across the Sahelian region was calcu- procedures lated using historical MODIS (Moderate-resolution Imaging Spectroradiometer) data (NASA, )for–;fires  We extracted distribution data for spurred tortoises in West detected covered at least , m . A point shape file was Africa from the literature (Trape et al., ; Petrozzi et al., clipped, as for cattle distribution, with each presence cell , ; Fig. a) and from original records collected by and each absence cell. In each cell, we determined the ourselves. Available data for Sudan, Ethiopia and Eritrea mean number of fires per day.

FIG. 1 Location of (a) presence and absence grid cells in a survey of the African spurred tortoise Centrochelys sulcata across the West African Sahel, with the reference numbers used in Table S; (b) the potential distribution of cattle density, and the six sites with the highest recorded densities of spurred tortoises (white circles); and (c) the spatial distribution of fire intensity. Black grid cells in (a) were excluded from analyses.

Trade analysis student t-test, with α set at %. One thousand bootstrap samples were calculated, and contrasted with real data. As We extracted all raw data available for spurred tortoises for the inequality of variance was found in the dataset (Levene’s – period from the CITES trade database (CITES, test, F = .,P, .), equality of variance was not as-  ). Each record of import/export included the country of sumed in the analysis. origin, whether the tortoise had been bred in captivity or For the trade analysis, the correlation between (log) num- taken in the wild, the purpose of the trade (e.g. commercial, ber of traded individuals and year was examined using a poly- scientific), and whether specimens were exported dead or nomial model. The Akaike information criterion (AIC) for alive, and whole or as parts (e.g. skins, shells, meat). It would this relationship was calculated. be naïve to assume that all species trade in the study area was legal, based on national quotasrecordedinthe CITES datasets. Many specimens are collected illegally in the countries of the Results Sahel and exported to Togo for the international pet trade (Auliya et al., ), and the species is also sought for the Tortoises and cattle local pet trade (Petrozzi et al., ). The geographical distribution of presence sites in relation to the density of cattle across West Africa is shown in Fig. a,b. Statistical analyses In general the density of cattle per grid cell tended to be higher in the southern part of the tortoise’s distribution, All statistical analyses were conducted using PASW . in particular in the cells located in Nigeria and southern (IBM, Armonk, USA). For each presence and absence grid Burkina Faso (where classes ,  and  were predominant), cell the proportionally dominant cattle density category aswellasinsouthernMali (whereclassesandwerepredom- (Supplementary Table S) was used as a proxy for the overall inant, with some small extensions of class ). The grid cells in effect of cattle on tortoises in the target grid cell; for ex- southern Senegal also showed a relatively broad extension of ample, if in a given grid cell the proportionally highest cattle  classes  and . In Chad only one of the presence grid cells density category was the fourth (i.e.  . x $  per km ), showed a broad extension of classes  and . The northern the value  was entered for that grid cell in the covariate part of the tortoise’s distribution was characterized by a con- variable of the logistic regression analysis. Presence/absence comitant low cattle density (classes ,  and, in small part, ). grid cells were then entered as dependent binary variables Mean cattle density, expressed in terms of the dominant ( = absence of tortoises in a given grid cell;  = presence cattle density category in a given grid cell, was significantly of tortoises in a given grid cell) and their cattle densities higher (t-test: P , .) in absence grid cells (x = . ± SD as covariates in a logistic regression model. Although the .,n=) than in presence cells (x = . ± .,n=). At predominant cattle density is a good indicator for a first ana- the six sites where our surveys found higher densities of lysis, with eight categories this dominant category may actu- spurred tortoises (authors, unpubl. data) the corresponding ally represent a tiny surface compared to the surface  cattle density values were always – individuals per km occupied by the other seven categories even if all of the (Fig. b). seven occupy surfaces that are smaller than that of the pre- In our logistic regression .% of cases were classified cor- dominant category. This introduces a bias. To prevent this rectly (i.e. assigned correctly as random or used basking sites) we also calculated an indicator score by dividing the per- at step  (i.e. no variables in the model, and before adding the centage of occurrence of the predominant category by the variable cattle density, which improved the model) and .% raw proportion of the surface it covers in the grid cell. of cases at step  (i.e. after the final model was assessed by add- This indicator score was then inserted into a logistic regres- ingthevariablecattledensity,whichsignificantlyincreasedthe sion model in which the presence/absence of tortoises was model fitting). Overall, the model was statistically significant the dependent variable. The higher the score, the higher (B = –.,SE=.,Exp(B)=.,Wald=.,df=, the impact of grazing was, both in intensity and surface P=.). (per grid cell). For each presence and absence grid cell the fire intensity value was entered in a logistic regression model, as covariate, having verified that cattle density and Tortoises and fires fire intensity were not collinear in each cell (P . .). We used the forward stepwise model, which adds the sig- The spatial distribution of fire intensity is presented in nificant variables one-by-one to the model, starting with no Fig. c. Our logistic regression model showed that %of variables (step ) and testing the addition of the variables of cases were classified correctly (i.e. assigned correctly as ran- interest (cattle density and fire intensity) to improve the dom or used basking sites) at step  (i.e. no variables in the model. Differences in mean cattle density between presence model, and before adding the variable cattle density, which and absence grid cells were analysed using a two-tailed improved the model) and .% of cases at step  (i.e. after

without indication of the country of origin (the country of export is reported). Ghana, Togo, Benin, Mali and Sudan were the main countries of export reported for the species. The number of wild individuals traded decreased significantly from  (when export quotas were introduced), from a mean of . ± SD . per year during –  to a mean of . ± SD . per year during –  (Mann–Whitney U-test, z = –.,P, .). A het- erogeneity of slopes test showed that the slopes of the regression lines of number of exported individuals vs year were negative for wild individuals of known and unknown origin, and were significantly different between wild individuals of known origin and wild individuals of unknown origin (one- way ANCOVA: F = .,df=,,P, .).

Discussion

FIG. 2 Relationship between log number of traded individuals of Spurred tortoises, cattle density and fire intensity Centrochelys sulcata and year (–). Data are from the CITES trade database (CITES, ). The cell size in our grid of tortoise distribution ( ×  km) is larger than ideal. For this type of study an ideal grid cell the final model was assessed by adding the fire intensity size would have been  ×  km, as is typically used in variable and then the cattle density × fire intensity inter- modern atlases of vertebrate distribution. However, we action variable, which significantly increased the model fit- were limited to the larger grid cell size because this was ting). Overall, fire intensity alone did not influence the the size used for tortoise presence records in Trape et al. model significantly (B = .,SE=., Exp(B) = ., (). Our results should therefore be interpreted with Wald = .,df=,P=.), whereas the cattle density × some caution. fire intensity interaction variable was statistically significant Our study provided correlational evidence that livestock (Wald = .,P=.). When the indicator score of live- density affects the presence of spurred tortoises throughout stock density was entered in the logistic regression model it their range in the West African Sahel. This was shown by was found that higher values of the score had a significant two kinds of analyses (a statistical test of the differences in influence on the absence of the species, thus confirming pat- mean livestock density between areas where tortoises are terns explained above (B = –.,SE=.,Exp(B)=., present and absent, and a logistic regression model in Wald = .,df=,P, .). which the addition of the cattle density variable significantly enhanced the fit of a model of tortoise distribution, with a Tortoises and international trade high density of cattle significantly depressing the probability of presence of the spurred tortoise). As the analysis was per- According to the CITES database –, spurred tortoises formed at the global scale of the tortoise’s range, and surveys were traded annually during –. In total, , wild in- were probably more intensive in the more accessible areas of dividualswere traded during thisperiod (yearly x = . ± SD this logistically problematic and socio-politically unsafe re- .). There was a negative polynomial correlation between gion (i.e. in areas where livestock density may have been  yearand (log) numberof tradedindividuals (r = .,n=, higher), the negative correlation between cattle density   P , .; y = –.x – .x + .x + .;AIC=.; and spurred tortoise presence is likely to be correct. Fig. ). However, the relationship was clearly heteroscedastic, Circumstantial evidence has shown that the few sites with less variation in more recent years. where spurred tortoises are still abundant are characterized A considerable portion of specimens (.%) came from by a total absence of domestic cattle (e.g. in the ‘W’ National countries where the species does not occur (e.g. Togo, n = ; Park and the Termit Massif Total Reserve in Niger, where Ghana, n = ,) or where it is extinct (Cameroon, n = ; there is no livestock grazing pressure, LC encountered Chirio & LeBreton, ). Thus, we may conclude that for c.  tortoises per day). many of the individuals traded as wild, the true country of ori- The low density of spurred tortoises in areas where live- gin is unknown. It appears that specimens traded from Togo stock are present may be a direct result of interspecific com- originate in Burkina Faso, Niger and Mali (Petrozzi et al., ). petition for food and habitat but may also be a result of According to the CITES () database , individuals hunting by livestock rearers. The tortoises are eaten by peo- (.% of the total traded) were reported to be wild but ple throughout most of the Sahel, including in Burkina Faso

(Petrozzi et al., ), the Central African Republic, Mali Mali appears to have experienced the highest losses to the and Niger (LC, pers. obs.). Contemporary grazing patterns pet trade, with specimens exported by Ghana, Niger, Togo necessitate continual bush burning by livestock rearers and even Hungary and the USA declared to be of wild origin (Behnke, ; Smet & Ward, ; Solomon et al., ), in Mali (a total of , tortoises in  and  in ; and wildfire is known to be a threat to free-ranging popula- CITES, ). The decline of the species in Mali was there- tions of tortoises elsewhere (e.g. Hailey, ; Esque et al., fore predictable (Lambert, ), and new population sur- ; Bertolero et al., ; Santos & Cheylan, ) because veys are needed urgently. of its indirect effects on desert habitats, which can result in As the species has a scattered distribution (e.g. Diagne, changes in dietary composition and loss of vegetation cover, ;Arvyetal.,), and most specimens originate from an increase in predation and loss of protection from tem- single collection localities (G.H. Segniagbeto & L. Luiselli, un- perature extremes (Esque et al., ). Our logistic regres- publ. data), it is essential to collect data on population trends sion modelling showed that fire intensity decreased the at exploitation sites in order to minimize the risk of further probability of finding a tortoise population within a given local extinctions (Chirio & LeBreton, ). The majority grid cell even more than the density of cattle alone, although of so-called wild specimens of Centrochelys sulcata traded fire intensity alone did not determine the presence/absence during – were of unknown origin. This raises ques- of tortoises within a given grid cell. Future studies should tions about the reliability of the CITES database and should verify experimentally the competitive mechanism between be taken into consideration in future analyses of trade in spurred tortoises and domestic livestock, to guide more pre- spurred tortoises and other chelonians. cisely the conservation management actions for this threa- The putative impact of illegal trading in this tortoise spe- tened species while minimizing negative impacts on cies is considerable, as the trade of reptiles from north-west impoverished human populations throughout the Sahel re- Africa is mostly illegal (and hence not recorded by the gion. Where cattle are present, people are too, and they may CITES database), facilitated by hyperporous geographical eat tortoise meat (Petrozzi et al., ). Thus, grazing may boundaries between countries and social instability. In not be the only cause of the tortoise’s decline, and other fac- some regions spurred tortoises are eaten regularly (Petrozzi tors are also relevant (e.g. habitat loss, wild and human- et al., ), which could heighten the risk of extinction. made fires, hunting, and competition with livestock).

Conclusions Spurred tortoises and the international pet trade We analysed three factors that could be threatening wild po- Data on the potential threat to the spurred tortoise from the pulations of C. sulcata throughout its range: competition for international pet trade are incomplete. In particular, the sig- food and space with domestic livestock (Branch, ), nificant variation in the number of tortoises traded legally wildfire intensity, and the international pet trade (CITES, each year suggests that the CITES database failed to record ). We found () a clear negative correlation between in-  all the tortoises exported from the study region. tensity of grazing (expressed as density of cattle per km ) It appears that the number of wild individuals traded has and presence of spurred tortoises, () an increased detri- been decreasing over the years and that the number of wild mental effect of cattle density when coupled with high fire individuals for which the country of origin is unknown is intensity, and () a consistent decrease in annual exports now approaching zero. The number of wild individuals of wild individuals for the pet trade following the introduc- traded during – is remarkable for a large tion of export quotas by country and by year, possibly be- K-selected species with delayed sexual maturity (Branch, cause the trade moved partially from legality to illegality ). The reduction in yearly exports is probably attribut- (i.e. given the increased difficulty in exporting wild indivi- able to multiple causes, including the establishment of export duals, such exports may now be hidden). Comparatively, quotas by country and by year, and possibly the reduced domestic livestock appear to be a greater threat to the tor- number of individuals remaining in the wild. Experienced toise than fire or international trade, as there is no evidence reptile dealers in Lomé, Togo, who usually trade the tortoises that management of grazing has been better in recent years with Europe or the USA, reported to us that it is increasingly compared to the previous decades across the Sahel region. difficult to obtain the species from local hunters because it is On the other hand, the number of wild individuals exported considerably rarer than in the recent past in the traditional for the pet trade appears to be relatively low at present, al- places of capture in Burkina Faso, Mali and Niger (G.H. though monitoring should continue. We recommend: () Segniagbeto & L. Luiselli, unpubl. data). The spurred tortoise precautionary listing of the spurred tortoise on Appendix is now apparently rare in nearly all sites where it is known to I of CITES, to prevent further exploitation of wild indivi- occur (e.g. Petrozzi et al., , ), apart from a few remote duals for the international pet trade, as already suggested semi-desert areas of Niger and Mali (L. Chirio, unpubl. data). by the CITES authorities (CITES, ); () that more

data be obtained to examine causal relationships, for example, soumise au titer de la résolution Conf. . . Https://cites.org/fra/ by monitoring changes in cattle density in time and space on cop//prop/.pdf [accessed  November ].   CITES () Consideration of Proposals for Amendment of relevant temporal and spatial grids (monthly and × km,     Appendices I and II Prop. . . Http://www.cites.org/eng/cop/ / respectively); and ( ) to improve the available data on the via- prop/.pdf [accessed  November ]. bility of spurred tortoise populations. We are planning to CITES () CITES Trade Database. Https://trade.cites.org/ work jointly with governmental and non-governmental orga- [accessed  November ]. nizations and agencies to implement recommendations and DIAGNE,T.() Etude et conservation de Geochelone sulcata au follow-up initiatives based on the data presented here. Sénégal. In Proceedings of the International Congress of Chelonian Conservation Proceedings, pp. –. SOPTOM, Gonfaron, France. ESQUE, T.C., BÚRQUEZ, A.M., SCHWALBE, C.R., VAN DEVENDER, T.R., ANNING, P.J. & NIJHUIS, M.J. () Fire ecology of the Sonoran Acknowledgements desert tortoise. In The Sonoran Desert Tortoise: Natural History, Biology and Conservation (ed. T.R. Van Devender), pp. –. Some of the data were recorded during field surveys funded by University of Arizona Press, Tucson, Arizona. the Mohamed Bin Zayed Species Conservation Fund (grant ESQUE, T.C., SCHWALBE, C.R., DEFALCO, L.A., DUNCAN, R.B. & no. , to F. Petrozzi) and by the Turtle Conservation HUGHES, T.J. () Effects of desert wildfires on desert tortoise Fund (granted to F. Petrozzi). This article benefited from (Gopherus agassizii) and other small vertebrates. The Southwestern Naturalist, , –. the critical comments of two anonymous referees. FAO (FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS)() Gridded Livestock of the World . FAO, Rome, Italy. Author contributions FURIERI,A.() SpatiaLite open source library. Https://www. gaia-gis.it/fossil/libspatialite/home [accessed  November ]. FP and LL designed the study. FP conducted the GIS ana- HAILEY,A.() The effects of fire and mechanical habitat lyses. EAE, GCA, NA, EMH, TD, GHS and LC conducted destruction on survival of the tortoise Testudo hermanni in northern the field surveys and collected presence data for the species. Greece. Biological Conservation, , –.  GA and LL conducted statistical analyses and drafted the KAGONÉ,H.( ) Gestion durable des écosystèmes pâturés en zone nord-soudanienne du Burkina Faso. PhD thesis. Faculté article, and all authors read and revised the article. Universitaire des Sciences agronomiques de Gembloux, Belgium. LAMBERT, M.R.K. () On growth, sexual dimorphism, and the general ecology of the African spurred tortoise, Geochelone sulcata, References in Mali. Chelonian Conservation and Biology, , –. LARGEN, M.J. & SPAWLS,S.() The Amphibians and Reptiles ARVY, C., MARISSAL, N., DIA, A.T. & COLAS,F.() Observations of Ethiopia and Eritrea. Frankfurt Contributions to Natural History, sur la répartition et les dimensions de Geochelone sulcata Volume . Edition Chimaira, Frankfurt am Main, Germany. (Cryptodira, Testudinidae) en Mauritanie occidentale. Bulletin de la MALLON, D.P., HOFFMANN, M., MCGOWAN, P.J.K. & VAN VLIET,N. Société herpétologique de France, , –. () An IUCN situation analysis of terrestrial and freshwater fauna AULIYA, M., ALTHERR, S., ARIANO-SANCHEZ, D., BAARD, E.H., in West and Central Africa. IUCN, Gland, Switzerland. BROWN, C., BROWN, R. et al. () Trade in live reptiles, its impact NASA () Fire Information for Resource Management System on wild populations, and the role of the European market. Biological (FIRMS). Https://firms.modaps.eosdis.nasa.gov/download/ Conservation, , –. [accessed  May ]. BARRY, S., ILLY, L., KARGOUGOU, I., KONDÉ, M., OUÉDRAOGO, S., PETROZZI, F., HEMA, E.M., LUISELLI,L.&GUENDA,W.()A PARKOUDA, S. et al. () Etude sur la typologie des exploitations survey of the potential distribution of the threatened tortoise agricoles familiales et adoption d’une nouvelle stratégie agricole. Centrochelys sulcata populations in Burkina Faso (West Africa). Rapport définitif. FAO, Ouagadougou, Burkina Faso. Tropical Ecology, , –. BEHNKE, R.H. () Open Range Management and Property Rights in PETROZZI, F., LUISELLI, L., AKANI, G.C. & ENIANG, E.A. () Pastoral Africa. A Case of Spontaneous Range Enclosure in South Supplementary distribution data of Centrochelys sulcata Darfur, Sudan. Pastoral Development Network Paper. Overseas (Miller, ), in northern Nigeria (West Africa). Herpetozoa, , Development Institute, London, UK. –. BERTOLERO, A., CHEYLAN, M., HAILEY, A., LIVOREIL,B.& QGIS DEVELOPMENT TEAM () QGIS Geographic Information WILLEMSEN, R.E. () Testudo hermanni (Gmelin )— System. Open Source Geospatial Foundation Project. Http://www. Hermann’s tortoise. In Conservation Biology of Freshwater Turtles qgis.org [accessed  November ]. and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and ROBINSON, T.P., WINT, G.R.W., CONCHEDDA, G., VAN BOECKEL,T. Freshwater Turtle Specialist Group (eds A.G.J. Rhodin, P.C. P., E RCOLI, V., PALAMARA, E. et al. () Mapping the global H. Pritchard, P.P. van Dijk, R.A. Saumure, K.A. Buhlmann, J. distribution of livestock. PLoS ONE (): e. Dataset on cattle B. Iverson & R.A. Mittermeier), pp. .–.. Chelonian density available at: Http://www.fao.org/geonetwork/srv/en/main. Research Foundation, Lunenburg, USA. search?extended=off&remote=off&any=glw+&themekey=& BRANCH,B.() Tortoises, Terrapins and Turtles of Africa.New to=&from=&siteId=&hitsPerPage=. Holland Publishing, Cape Town, South Africa. SANTOS,X.&CHEYLAN,M.() Taxonomic and functional CHIRIO,L.&LEBRETON,M.() Atlas des reptiles du Cameroun. response of a Mediterranean reptile assemblage to a repeated fire MNHN and IRD, Paris, France. regime. Biological Conservation, , –. CITES () Amendement aux annexes I et II de la CITES, Transfert SMET,M.&WARD,D.() A comparison of the effects of different de Geochelone sulcata de l’Annexe II à l’Annexe I; Proposition rangeland management systems on plant species composition,

diversity and vegetation structure in a semi-arid savanna. African Biographical sketches Journal of Range and Forage Science, , –. SOLOMON, T.B., SNYMAN, H.A. & SMIT, G.N. () Cattle- FABIO PETROZZI works on the ecology and conservation of tortoises rangeland management practices and perceptions of in the Sahelian region. EDEM ENIANG,GODFREY AKANI and pastoralists towards rangeland degradation in the Borana zone NIOKING AMADI work on the ecology and conservation of Nigerian of southern Ethiopia. Journal of Environmental Management, , reptiiles. EMMANUEL HEMA works on the conservation of mammals –. and reptiles in Burkina Faso, Mali and Niger. TOMAS DIAGNE TORTOISE &FRESHWATER TURTLE SPECIALIST GROUP () specializes in the conservation of African chelonians. He is the Centrochelys sulcata. The IUCN Red List of Threatened Species : president of the African Chelonian Institute (Dakar). GABRIEL e.TA. Http://dx.doi.org/./IUCN.UK..RLTS. HOINSOUDÉ SEGNIAGBETO works on the conservation ecology of TA.en [accessed  November ]. reptiles in Togo and Ghana. LAURENT CHIRIO works on the distribu- TOURÉ, S.M., FERRARA, B., LOPEZ, G., MATTIOLI, R., BARBERA,S.& tion patterns of reptiles in Africa. GIOVANNI AMORI works on the DISSET,R.() Etude générale de l’élevage au Burkina Faso.FAO, conservation and biology of mammals and reptiles in Africa and Ouagadougou, Burkina Faso. elsewhere. LUCA LUISELLI works on the community ecology TRAPE, J.F., CHIRIO,L.&TRAPE,S.() Lézards, crocodiles et tortues and conservation biology of West African vertebrates, particularly d’Afrique occidentale et du Sahara. IRD Editions, Paris, France. reptiles.