Comparative Food Habits and Body Size of Five Populations of Elaphe quatuorlineata: the Effects of Habitat Variation, and the Consequences of Intersexual Body Size Dimorphism on Diet Divergence
The comparative diet and body size of the Four-Lined Snake (Elaphe quatuorlineata), one of the largest and more vulnerable species of snakes in Mediterranean central Italy, were studied in five different habitats. Data given here collated both literature and original data. Overall, females were significantly larger than males but the strength of these differences varied considerably with sample size. Overall, small mammals (almost exclusively rodents) accounted for the main part of the diet (66.7%), followed by birds and their eggs (mainly Passeriformes; 26.4%), and by lizards (6.9%), although the number of eggs in the diet was probably greatly underestimated. In qualitative terms, both sexes fed on the same prey types, but, quantitatively, males and females differed significantly in terms of prey composition; females fed on more birds and fewer lizards than males. Rodents were the most important prey source in most habitat types, although birds were preyed upon slightly more frequently in the wet habitat than rodents, which, nonetheless, still represented a important prey source. Four-Lined Snakes started feeding in early April and continued feeding until early November. The monthly frequency of occurrence of birds in snake stomachs differed significantly from that of small mammals; birds were taken almost exclusively in April and May (and mainly by females), and small mammals were taken all throughout the annual feeding cycle of snakes.Abstract
Mean SVL (±SD and SE) for Four-Lined Snakes in the five study areas. Only the SVL of snakes captured for the first time are included. Symbols: AG = agro-forest; BP = bushy pasture; RF = residual forest; MA = macchia; WET = wet area; M = males; F = females. Sample sizes: AG–8 and 8 (males and females), BP–17 and 14, RF–13 and 11, MA–24 and 16, WET–20 and 21. For statistical details, see the text
Monthly distribution (%) of small mammals and birds in the stomachs of Four-Lined Snakes from different habitat types in Mediterranean central Italy. Data from male and female snakes, and from all the five study areas, are summed in this graphic. Sample sizes: for small mammals n = 116; for birds n = 45
Dendrogram resulting from a hierarchical cluster analysis (UPGMA, standardized to 100%) of percentage composition of snake diets in the various habitat types (study areas)
Contributor Notes
(EF) F.I.Z.V., Herpetology Section, via Gabrio Casati 43, I-00139 Rome, Italy; (LR) F.I.Z.V., Herpetology Section, via Domenico Cimarosa 13, I-00198 Rome, Italy; (MC) Museo Civico di Zoologia, Section of Herpetology, via Ulisse Aldrovandi 18, I-00197 Rome, Italy; (DC) Regione Lazio, Agenzia Regionale per i Parchi (ARP), via Indonesia 33, I-00144 Rome, Italy; and (LL) F.I.Z.V. Ecology Section and Centre of Environmental Studies Demetra, via Olona 7, I-00198 Rome, Italy. (LL) lucamlu@tin.it Send reprint requests to LL.