Sexual dichromatisation and sexual differences in hunting behavior and dietary intake in a free-ranging small viperid snake, Cerastes vipera

Abstract

The tip of the tail in female Cerastes vipera, a small viperid snake, is black and conspicuous, whereas that of the male is not. We tested the hypothesis, albeit indirectly, that this sexual dimorphic chromatisation is related to caudal luring, a feeding mimicry hunting strategy. C. vipera can hunt nocturnally-active lizards only via sit-and-wait ambush and, consequently, we predicted that females would use caudal luring more often than males and that the proportion of nocturnal prey items in the diet of females would be higher than in males. Our hypothesis was supported as: 1) only females demonstrated caudal luring towards nocturnally-active lizards and more than 85% did so, whereas none of the males demonstrated such behavior; and 2) females consumed a significantly higher proportion (15/40 vs 4/27) of nocturnally-active lizards than did males. We concluded that sexual dichromatisation in C. vipera is associated with hunting strategy that results in different hunting behavior and different dietary intake between sexes. These novel findings: 1) provide a functional explanation for the black tail of female C. vipera; and 2) suggest different evolutionary driving forces between sexes and, consequently, different ecological impacts of male and female C. vipera on lizard populations.