402 Herpetological Conservation and Biology 12(2):402–409. Submitted: 5 January 2017; Accepted: 23 May 2017; Published: 31 August 2017. Copyright © 2017. Fabio Petrozzi All Rights Reserved. Introduction Habitat loss is considered one of the main drivers of the extinction reptiles worldwide, with approximately 74% of threatened species being impacted by agricultural practices, 64% by logging and harvesting and 22% by climate change (Böhm et al. 2013, 2016). Despite the negative efect of habitat loss for many threatened terrestrial reptiles (Böhm et al. 2013), there are virtually no feld studies devoted to understanding patterns of habitat use and/or selection, either at the local or at the regional scale for several species of high conservation concern. One species of conservation concern is the African Spurred Tortoise (Centrochelys sulcata; Fig. 1), described as the second largest tortoise species in the world, with a wide distribution across the African Sahel (Branch 2008). Despite its wide range in this region, this species has a patchy distribution, likely due to declines and extirpation of local populations (Branch 2008; Petrozzi et al. 2017) caused by extensive hunting for domestic consumption and the international pet trade (Luiselli et al. 2016). Nonetheless, because of the scarcity of historical (distributional and ecological) data on this species and the shortage of feld studies on habitat use/selection, it is difcult to evaluate whether the wide gaps in the distribution of this species are due to the extirpation of many populations or to the lack of understanding of habitat preferences at the local scale. Petrozzi et al. (2017) observed that the overall distribution of the African Spurred Tortoise is Habitat Determinants of the Threatened Sahel Tortoise Centrochelys sulcata A t Two Spatial Scales Fabio Petrozzi 1 , Emmanuel M. Hema 2 , Djidama Sirima 2 , Benoit Douamba 3 , Gabriel Hoinsoudé Ségniagbeto 4 , Tomas Diagne 5 , Nioking Amadi 6 , Giovanni Amori 7 , Godfrey C. Akani 6 , Edem A. Eniang 8,10 , Laurent Chirio 9 , and Luca Luiselli 6,10,11 1 Ecologia Applicata Italia s.r.l., via Edoardo Jenner 50, 00155 Rome, Italy 2 Université Ouaga 1 Professeur Joseph Ki ZERBO/CUP-D, laboratoire de Biologie et Ecologie Animales, Ouagadougou, Burkina Faso 3 Ministère de l’Environnement, de l’Economie Verte et des Changements Climatiques, Ouagadougou, Burkina Faso 4 University of Lome, Faculty of Sciences, Department of Zoology, BP: 6057 Lome Togo. Email: 5African Chelonian Institute, Ngaparou-Mbour, Senegal 6 Department of Applied and Environmental Biology, Rivers State University of Science and Technology, P.M.B. 5080 Nkpolu, Port Harcourt, Rivers State, Nigeria 7 National Research Council (CNR) Institute of Ecosystem Studies, Rome, Italy 8 Department of Forestry and Natural Environmental Management, Faculty of Agriculture, University of Uyo, Akwa Ibom State, Nigeria 9 Museum National d’Histoire Naturelle, Paris, France 10 IDECC - Institute for Development, Ecology, Conservation and Cooperation, via G. Tomasi di Lampedusa 33, I-00144 Rome, Italy 11 Corresponding author, e-mail: l.luiselli@ideccngo.org Abstract.—The African Spurred Tortoise (Centrochelys sulcata), the second largest tortoise species in the world, is threatened with extinction because of a variety of threats, including habitat loss. Because details of habitat use for this species have not been published for wild populations of this species, we conducted this study to qualify and quantify habitat selection at two spatial scales in Burkina Faso and Niger (West Africa). Tortoises were active above-ground almost exclusively in August, during the peak of the wet season. We surveyed seven potential habitat types but the majority of adult and juvenile tortoises were observed in only two, dry river beds (locally named kori) and stabilized dunes. We used GIS (Geographical Information System) to map the known distribution of the African Spurred Tortoise in both countries in relation to the availability of kori. The habitat preference of African Spurred Tortoises widely overlaps with the occurrence of kori (and not permanent rivers or other water bodies) in the landscape. We discuss the biological and ecological reasons explaining the results, as well as the conservation consequences. Key Words.—conservation; ecology; habitat selection; Sahel; tortoise; West Africa