The Herpetological Journal

pp.13-19

Authors: José C. Brito

Abstract: The diet of Vipera latastei was investigated in northern Portugal from 1998 to 2002. Palpation of stomach contents and forced defaecation from 1 90 snake specimens resulted in the recovery of 83 identifiable prey items. V. latastei preys on four species of small mammal (76%), two lizard species ( 14%), three amphibian species (5%) and arthropods s.l. (5%). Estimates of prey availability demonstrated that the most common prey were also the most frequent prey consumed. No differences between the sexes were detected in terms of the proportion of snakes with prey or diet composition. However, there was an ontogenetic shift in diet composition. Juveniles fed mostly on ecthotermic prey (60%), the majority of subadults fed on insectivorous mammals and lizards (60%), and adults fed mainly on rodents ( 8 8%). This ontogenetic shift is mostly due to the morphological constraints imposed on the juvenil es, which cannot swallow large prey items. There is a positive correlation between snake size and prey size. V. latastei is selective in terms of both the species and size of prey ingested, with larger snakes being more selective than smaller snakes. Larger snakes have a narrower food niche breadth than smaller snakes, but their diet composition overlaps moderately. There is seasonal variation in the diet composition, with snakes taking amphibians mainly in spring and autumn, lizards in spring, and mammals in summer and autumn. Feeding frequencies indicate that both males and females - and subadults and adults - consume prey more frequently during summer.

Keywords: dietary habits, food selection, prey availability, snakes, Viperidae