title: Palestine Saw-scaled Vipers hunt disadvantaged avian migrants.
abstract: The selection of an ambush-cum-foraging site and proper prey are indispensable for maintaining an adequate energy intake by sit-and-wait predators to optimize survival and future fitness. This is important for snakes, where an ambush site has suitable ambience. We studied the foraging strategy of the Palestine Saw-scaled Viper (Echis coloratus) at an avian migratory stopover site. Following initial observations, we hypothesized that vipers are able to discern the body mass of a perched bird and hunt accordingly. We implemented an experiment where vipers chose between four groups of migratory Blackcaps with different body mass. Prey choice by vipers of both age classes was not random and adults focused on Blackcaps with the lightest body mass. Juveniles displayed a variability of prey choice but selected mainly birds from the lightest categories. We concluded that Saw-scaled Vipers hunt prey based on thermal cues; juveniles practice on different prey groups prior to perfecting their foraging techniques i.e., hunting is a learned process; and that they prefer birds with the lowest body mass. The last because Blackcaps, when on migration, save energy by entering a state of deep torpor in which they sacrifice their vigilance capabilities.
authors: International Birding and Research Centre in Eilat, P.O. Box 774, Eilat 88000, Israel; Department of Life Sciences, Ben Gurion University, Beer Sheva, Israel.
authors: Reuven
authors: R
authors: Yosef
authors: Department of Avian Biology and Ecology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznań 61-614, Poland. Electronic address: kudlaty@amu.edu.pl.
authors: Piotr
authors: P
authors: Zduniak
mesh_terms: D025041:Animal Migration / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001717:Birds; D005247:Feeding Behavior / Q000502:physiology*; D011235:Predatory Behavior / Q000502:physiology*; D017819:Viperidae / Q000502:physiology*
keywords: Avian migrants; Body mass; Echis coloratus; Foraging; Sylvia atricapilla; Vigilance