Habitat use and preliminary demographic evaluation of the critically endangered Mediterranean monk seal (Monachus monachus) in the Cilician Basin (Eastern Mediterranean) Ali Cemal Gucu*, Gul Gucu, Hasan Orek Middle East Technical University, Institute of Marine Sciences, PO Box 28, Erdemli, 33731 Icel, Turkey Received 27 March 2003; received in revised form 30 May 2003; accepted 9 June 2003 Abstract Over the last few decades a dramatic decline in the number of Mediterranean monk seals (Monachus monachus) limited scientific studies on the biology, behaviour, and ecology of the species. This lack of information impaired the effectiveness of conservation strategies. Thus, any further information gathered on the monk seal has utmost value in the work to halt and reverse the plight of the species. A hitherto unknown Cilician Basin colony of the Mediterranean monk seal has been investigated during a 6-year period between 1995 and 2001. Results of direct in-cave surveys and land based seal-watch observations enabled the evaluation of habitat use and preliminary demographic information. A total of 39 caves were discovered among which only three were used for breeding. Scarcity of the breeding caves emphasised the importance of breeding habitat in the survival of the colony. Common features of the breeding caves are found as an entrance with a protective barrier against strong waves; a chamber with a wide beach; and a well- sheltered shallow pool. Supplementary data obtained from infrared monitors installed in three actively used caves were used to assess the number of individuals. Throughout the study period, 25 individuals were identified and 11 newborn pups were found. Evaluation of the results suggests the presence of sub-regions inhabited by an individually identified sub-group of monk seals. Recommendations for conservation guided by this information is a Marine Protected Area consisting of two zones; a restricted core zone prohibiting any human activity securing breeding habitat and a restricted fishery zone securing sustainability of the food source. # 2003 Elsevier Ltd. All rights reserved. Keywords: Monachus monachus; Habitat use; Demography; Conservation; Cilician Basin 1. Introduction The Mediterranean monk seal, Monachus monachus (Hermann, 1779) has been classified as ‘‘Critically Endangered’’ since 1966 by the Species Survival Com- mission of the World Conservation Union (IUCN) and today, it is protected by Bonn (Appendix I and II), Bern (Appendix II), CITES (Appendix I), Barcelona (Fourth protocol species), and Biodiversity (Eligible species) Conventions. The Mediterranean monk seal is the rarest existing species in the Phocidae family and the sixth most threatened mammal in the world (Panou et al., 1993). In the seventies, around 600–1000 individuals were believed to survive in the Mediterranean Sea (Sergeant et al., 1978; Marchessaux, 1989). In 1997, the largest popula- tion of the species experienced a dramatic die-off in the western Sahara and approximately 200 seals died (Har- wood et al., 1998). After this loss, other reproductive colonies in Maidera (Neves and Pires, 2000), Alonissos (HSSPMS, 1995; Dendrinos et al., 1996), Kefalonia (Jacobs and Panou, 1988), Foca (Guclusoy and Kence, 2001) as well as the less known, small fragmented groups scattered in few remote locations such as in the Cilician Basin, gathered substantial attention. Con- sidering that the total number of monk seals throughout the range is estimated to be between 400 and 500 indi- viduals, the collective number of the above mentioned fragmented colonies consist 60% of the entire popula- tion and have vital importance in terms of survival of 0006-3207/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0006-3207(03)00234-9 Biological Conservation 116 (2004) 417–431 www.elsevier.com/locate/biocon * Corresponding author. Tel.: +90-324-521-3434; fax: + 90-324- 521-2327. E-mail address: gucu@ims.metu.edu.tr (A.C. Gucu).