Diet of the Viviparous lizard Zootoca vivipara (Lichtenstein, 1823) (Reptilia: Lacertidae) from its southern range

Abstract

Although the Viviparous lizard (Zootoca vivipara) is one of the most successful lizard species and is widespread across Eurasia, data on its dietary habits are still lacking, especially from the southern part of its range. In order to shed light on its diet, we conducted а study in three high mountains in Bulgaria, which represent separate “patches” from the range of Z. vivipara in the country. To investigate the food preferences, we adopted a non-invasive method using faecal samples and a total of 290 faecal samples that could be assigned to individual specimens with determined age and sex were collected. A total of 19 prey categories were detected and the number of categories per each study site varied between 16 and 18, which indicates opportunistic feeding habits. The most preferred prey types were Auchenorrhyncha (Order Hemiptera) and Araneae, while Formicidae and Opilones, abundant in the field, were avoided. Two physical characteristics of the prey, hardness and evasiveness, were analysed. In respect to hardness, Z. vivipara choose more often hard prey, and in respect to evasiveness, sedentary prey was consumed more often, hence we could suggest that Z. vivipara is an active forager. Statistically significant differences between immatures and adults were found as adults showed more diverse diet. No such differences between sexes were detected. Two cases of (partial) cannibalism and many cases of keratophagy (in 9% of the faecal pellets) were detected.