Data from: Foraging mode, relative prey size and diet breadth: a phylogenetically-explicit analysis of snake feeding ecology

1. Foraging modes (ambush vs. active foraging) are often correlated with a
suite of morphological, physiological, behavioral and ecological traits
known as the adaptive syndrome or syndrome hypothesis. In snakes, an
ecological correlate often reported in the literature is that
ambush-hunting snakes have a higher relative meal size compared to
actively foraging snakes which feed on smaller prey items. This “large
meal vs. small meal” feeding hypothesis between ambush and active foragers
has become a widely-accepted paradigm of snake feeding ecology, despite
the fact that no rigorous meta-analysis has been conducted to support this
generalization. 2. We conducted a phylogenetically-explicit meta-analysis,
which included ca. 100 species, to test this paradigm of snake feeding
ecology. 3. We gathered data on prey size by inducing regurgitation by
palpation in free-ranging snakes and by examining the stomach contents of
preserved museum specimens. When we found prey, we recorded both snake and
prey mass to estimate relative prey mass (prey mass/snake mass). We also
reviewed published studies of snake feeding ecology to gather similar
information for other species. 4. Ambush and active foragers did not
differ in minimum or average meal size but the maximum meal sizes consumed
by ambush-foraging snakes were larger than the maximum meal sizes eaten by
active foragers. This results in ambush-foraging snakes consuming a
significantly wider range of meals sizes, rather than being large meal
specialists compared to active foragers. We argue that ambush foragers
evolved to be more opportunistic predators because they encounter prey
less frequently compared to active foragers. This hypothesis is further
supported by the fact that ambush foragers also exhibited marginally wider
diet breadths, consuming a broader range of prey types in comparison to
active foragers. 5. Our study challenges aspects of the foraging syndrome
as it is currently conceived, and our results have important implications
for our understanding of how foraging mode has shaped the behavior and
physiology of ambush-foraging snakes.