The space utilization by the reptiles in Prespa National Park

Abstract

In the first part of this paper data are presented on the habitat segregation of the reptile species of Lake Prespa National Park. Twenty species of reptiles are present in the study area. Most of them are of East-Mediterranean origin, some are Balkan endemics and a few are of northern origin. Systematic surveys and counts of reptiles were conducted in each of the following habitats: marshes and reedbeds, wet meadows, rocky coastal areas and sandy beaches, cultivated land, grazing lands, mixed deciduous, oak and beech forests, sub-alpine and alpine meadows. A list is provided of the typical reptile species occurring in each of these habitats, with notes on abundance and habits. The highest reptilian diversity was found in man-made/modified habitats, namely the farmland zone, which structurally is the more diversified. There was a dramatic fall of species richness with increasing altitude. The second part of the paper describes qualitative differences in habitat utilization among the members of the two major reptilian groups, lizards and snakes. The Sand Lizard Lacerta agilis is found exclusively in the alpine and subalpine grasslands above 1600 m. asl., the Common Wall Lizard Podarcis muralis is the more euryecous while all other Lacertids show a clear specialization in habitat use though retaining various degrees of overlap. Among snakes the Adder Vipera berus is restricted to high mountain grasslands, the two Natrix species are common and more or less confined to areas close to the lakes while the Nose-horned Viper Vipera anmmodytes the third commonest species of the area prefers rocky/stony slopes.The notes on habitat utilization by the remaining species of snakes are only of indicative value because of small number of observations.