A trait‐based framework for understanding predator–prey relationships: Trait matching between a specialist snake and its insect prey

Abstract

High‐quality information on predator–prey relationships is fundamental in understanding food webs, community assembly and ecosystem functioning. Recent analytical advances have made it possible to develop new trait‐based approaches to study trophic relationships and evaluate trait matching between predators and prey. Here, we develop a novel analytical approach based on generalized linear mixed‐effects models (GLMM) to test the importance of prey availability and to identify the set of prey traits that best explain the occurrence and number of prey in the predator's diet. We demonstrate that the approach by using an extensive dataset on prey availability, prey traits and gut content collected in all known populations of Vipera graeca, a little‐known, endangered snake of alpine grasslands in the Pindos Mountains of the Balkan Peninsula. We show that V. graeca is a unique, venomous snake specialized on bush‐crickets and grasshoppers (Orthoptera). Prey selection GLMMs showed that the ideal prey of V. graeca is abundant, large‐bodied, has poor escape abilities (flightless, slow‐moving and bad jumper) and prefers loose grasslands (as opposed to bare ground/rock or closed sward). Vipers restrict their feeding to periods of high Orthoptera abundance in the late summer and need to reach a certain body size to become able to catch large‐sized prey. Our analytical approach provides a framework for trait matching between predators and prey and unprecedented fine‐scale information on the importance of prey traits in prey selection by a specialist predator. The narrow trophic niche of V. graeca likely increases the vulnerability of this cold‐adapted snake to extinction. A free Plain Language Summary can be found within the Supporting Information of this article.

Analysis of mammal mesopredator scat samples indicates significant predation on the endangered Hungarian meadow viper (Vipera ursinii rakosiensis)

“…Meadow vipers (Vipera ursinii complex) are grassland specialist reptiles preying mostly on grasshoppers (Baron 1992, Filippi and Luiselli 2004, Mizsei et al 2019. Their global…”

“…Meadow vipers ( Vipera ursinii complex) are grassland specialist reptiles preying mostly on grasshoppers (Baron 1992, Filippi and Luiselli 2004, Mizsei et al 2019). Their global distribution follows the Steppe biome with some habitats located in extra‐zonal grasslands in Asia and Europe (Nilson and Andrén 2001).…”

Determining priority areas for an Endangered cold-adapted snake on warming mountaintops

“…These alpine habitats are threatened by overgrazing and habitat degradation, which simplify vegetation structure and reduce cover against potential predators. The species is strictly insectivorous, specializing on bush crickets and grasshoppers (Mizsei et al, 2019), and thus it is vulnerable to changes in its primary prey resource caused by land use. Shepherds are known to intentionally kill these snakes, which are held responsible for 1–4% of lethal bites to sheep annually in Albania (E. Mizsei, unpubl.…”

Microhabitat selection of meadow and steppe vipers enlightened by digital photography and image processing to describe grassland vegetation structure

“…Considering the negative relationship in the latter species, it has to be noted that tall wetland plants were common in V. ursinii habitats, representing more dense cover and shading, which probably reduced the possibility of sunbathing for the vipers (Muri et al., 2015), which can explain why vipers appeared to avoid microhabitats with tall and dense vegetation. Furthermore, prey availability and the quality of the prey community can vary across both time and space, potentially exerting additional influence on microhabitat preferences (Mizsei et al., 2019). Further experimental studies are needed to investigate this trade‐off and the potential influence of prey availability on microhabitat selection in snakes.…”