Foraging decisions and behavioural flexibility in trap‐building predators: a review

Abstract

Foraging theory was first developed to predict the behaviour of widely-foraging animals that actively search for prey. Although the behaviour of sit-and-wait predators often follows predictions derived from foraging theory, the similarity between these two distinct groups of predators is not always obvious. In this review, we compare foraging activities of trap-building predators (mainly pit-building antlions and web-building spiders), a specific group of sit-and-wait predators that construct traps as a foraging device, with those of widely-foraging predators. We refer to modifications of the trap characteristics as analogous to changes in foraging intensity. Our review illustrates that the responses of trap-building and widely-foraging predators to different internal and external factors, such as hunger level, conspecific density and predation threat are quite similar, calling for additional studies of foraging theory using trap-building predators. In each chapter of this review, we summarize the response of trap-building predators to a different factor, while contrasting it with the equivalent response characterizing widely-foraging predators. We provide here evidence that the behaviour of trap-building predators is not stereotypic or fixed as was once commonly accepted, rather it can vary greatly, depending on the individual's internal state and its interactions with external environmental factors.

Caught in the web: Spider web architecture affects prey specialization and spider–prey stoichiometric relationships

“…We hypothesized that if web architecture influences spider–prey interactions, then spiders that build webs of different architectures will differ in the prey communities they capture, resulting in relative prey capture variability and degree of generalist trophic behavior as a function of web type. Furthermore, as web‐building spiders typically face prey heterogeneity in availability (i.e., abundance, variability, and predictability) and range of prey types (Scharf, Lubin, & Ovadia, 2011), and prey taxa can vary significantly in their nutrient composition (Fagan et al., 2002; González et al., 2011), hunting modes associated to different web architectures may affect the stoichiometry of spider–prey interactions. As generalist predators feed on a wide variety of prey, they may be able to selectively combine prey in their diets to balance their nutritional needs (Mayntz & Toft, 2001; Oelbermann & Scheu, 2002).…”

Humidity-mediated changes in an orb spider's glycoprotein adhesive impact prey retention time

“…Differences in diet and prey type cause striking differences in both a web's architecture and the properties of its threads (Blamires et al, 2016;Herberstein and Tso, 2011;Scharf et al, 2011;Townley et al, 2006;Tso et al, 2007), as can environmental factors such as wind (Wu et al, 2013). After a web has been spun, its frame and axial threads and its capture threads respond to daily changes in environmental conditions, with humidity having the greatest impact (Agnarsson et al, 2009;Sahni et al, 2011;Opell et al, 2011Opell et al, , 2013Stellwagen et al, 2014Stellwagen et al, , 2015Amarpuri et al, 2015).…”

Wind induces variations in spider web geometry and sticky spiral droplet volume

“…The use of traps to capture prey has evolved independently in arachnids, larval dipterans, trichopterans and neuropterans (Viviani et al, 2002;Hansell, 2005;Scharf et al, 2011). The principal advantage of building a trap is that once the trap is built, prey is captured at minimal expense of foraging time and energy (Lucas, 1985;Willis et al, 2011).…”

“…Thus, for traps to be profitable they must be composed of readily synthesizable materials that sustain their functionality for prolonged periods (Hansell, 2005). Additionally, as the traps may be exposed to spatially and temporally variable environments (Scharf et al, 2011), it is likely that the physical and chemical properties of the building materials will vary across different environments (Fudge et al, 2003;Hansell, 2005;Liao et al, 2009;Hansell and Ruxton, 2013).…”