A P System Modeling an Ecosystem Related to the Bearded Vulture M´ onica Cardona 1 , M. Angels Colomer 1 , Mario J. P´ erez-Jim´ enez 2 , Delf´ ı Sanuy 3 , Antoni Margalida 4 1 Dpt. of Mathematics, University of Lleida Av. Alcalde Rovira Roure, 191. 25198 Lleida, Spain E-mail: {mcardona,colomer}@matematica.udl.es 2 Research Group on Natural Computing Dpt. of Computer Science and Artificial Intelligence, University of Sevilla Avda. Reina Mercedes s/n, 41012 Sevilla, Spain E-mail: marper@us.es 3 Dpt. of Animal Production, University of Lleida Av. Alcalde Rovira Roure, 191. 25198 Lleida, Spain E-mail: dsanuy@prodan.udl.cat 4 Bearded Vulture Study & Proteccion Group Adpo. 43 E-25520 El Pont de Suert, Lleida, Spain E-mail: margalida@inf.entorno.es Summary. The Bearded Vulture is one of the rarest raptors in Europe and it is an endangered species. In this paper, we present a model of an ecosystem related with the Bearded Vulture which is located in the Catalan Pyrenees, by using P systems. The population dynamics constituted by the Bearded Vulture (that feeds almost exclusively on bones) and other five subfamilies that provide the bones they feed on, is studied. P systems provide a high level computational modeling framework which integrates the structural and dynamical aspects of ecosystems in a comprehensive and relevant way. P systems explicitly represent the discrete character of the components of an ecosystem by using rewriting rules on multisets of objects which represent individuals of the population and bones. The inherent stochasticity and uncertainty in ecosystems is captured by using probabilistic strategies. In order to give an experimental validation of the P system designed, we have con- structed a simulator that allows us to analyze the evolution of the ecosystem with different initial conditions. 1 Introduction An ecosystem is a natural unit consisting of all plants, animals and micro- organisms (biotic factors) in an area functioning together with all of the non-living physical (abiotic) factors of the environment.