Predator and Prey Space Use: Dragonflies and Tadpoles in an Interactive Game

Abstract

Predator and prey spatial distributions have important population and community level consequences. However, little is known either theoretically or empirically about behavioral mechanisms that underlie the spatial patterns that emerge when predators and prey freely interact. We examined the joint space use and behavioral rules governing movement of freely interacting groups of odonate (dragonfly) predators and two size classes of anuran (tadpole) prey in arenas containing two patches with different levels of the prey's resource. Predator and prey movement and space use was quantified both when they were apart and together. When apart from predators, large tadpoles strongly preferred the high resource patch. When apart from prey, dragonflies weakly preferred the high resource patch. When together, large prey shifted to a uniform distribution, while predators strongly preferred the high resource patch. These patterns qualitatively fit the predictions of several three trophic level, ideal free distribution models. In contrast, the space use of small prey and predators did not deviate from uniform. Three measures of joint space use (spatial correlations, overlap, and co-occurrence) concurred in suggesting that prey avoidance of predators was more important than predator attraction to prey in determining overall spatial patterns. To gain additional insight into behavioral mechanisms, we used a model selection approach to identify behavioral movement rules that can potentially explain the observed, emergent patterns of space use. Prey were more likely to leave patches with more predators and more conspecific competitors; resources had relatively weak effects on prey movements. In contrast, predators were more likely to leave patches with low resources (that they do not consume) and more competing predators; prey had relatively little effect on predator movements. These results highlight the importance of investigating freely interacting predators and prey, the potential for simple game theory models to predict joint spatial distributions, and the utility of using model choice methods to identify potential key factors that govern movement.

Separating spatial search and efficiency rates as components of predation risk

“…Ideally, broad-scale spatial models of predator numerical responses could also be integrated with functional and aggregative response models to convert relative per capita rates of predation into population-level modelling of both predator and prey population dynamics. Predator-prey interactions are complex games, wherein predators search for prey and prey avoid predators [24,25]. While predator-based studies such as this one have revealed spatial variation in multiple stages of predation such as search and kill rates [26], prey-based studies have also revealed differential avoidance and escape tactics as prey-mediated components of spatial risk [7].…”

Conspecific density affects predator‐induced prey phenotypic plasticity

“…Therefore, it is probable that predation cues were less dense at the bottom of the mesocosms due to the distance from the source. Such locations should be preferred by risk-averse individuals (Hammond et al 2007).…”

A “death trap” in the landscape of fear

“…Brown 1999;Verdolin 2006;Hammond et al 2007;Hochman and Kotler 2007;Valeix et al 2009b;Thaker et al 2011;Burkepile et al 2013;Laundré et al 2013;Venter et al 2014). Yet as prey species do not always have the chance to directly confront their predators, perception of predation risk should often rely on indirect cues.…”

“…What emerges from these ostensibly conflicting strategies is that it often leads to a negative relationship between the prey and predators' spatial distribution (Kunkel and Pletscher 2000;Orrock et al 2004;Creel et al 2005;Thaker et al 2011). An experimental study on dragonfly-tadpole spatial interactions revealed that when predators used a high resource patch more, prey used that patch less (Hammond et al 2007). The outcome of these interactions in the wild may, however, depend on various factors including a behavioural interplay between predator and prey (Mitchell and Lima 2002).…”