FEEDING-HABITS OF A MEDITERRANEAN COMMUNITY OF SNAKES IN RELATION TO PREY AVAILABILITY

Food habits of four sympatric terrestrial snakes (Vipera aspis, Colube r viridiflavus, Elaphe longgissima, Elaphe quatuorlineata) are studied in a forested area of the <<Roman Country>>, about 15 km northeast of Rome. All species proved to be extremely similar in food choice, prey ing primarily upon small mammals (rodents and shrews) and lacertid liz ards. Adult vipers occasionally preyed on brown frogs, while nestling birds were captured by all species (especially E. quatuorlineata) apar t E. longissima. We estimated the relative density of several potentia l prey (all the small mammals and three of the lizard species), and fo und highly positive relationships between prey availability and prey u se by snakes. Because of the high overlap between diets of the four sn ake species in the area, a strong interspecific competition may be pre dicted if the prey resource tends to decline.