Nutritional Status Does Not Restrict Foraging Activity and Web Investment in a Shelter-Building Spider Species, But Individuals are More Risk-Prone at Night

Abstract

Optimal foraging and individual specialization theories suggest that different properties of the interactions between prey and predators determine foraging strategies. However, none of these theories consider how the nutritional status of the predators and the risk of being attacked by other predators may affect prey foraging strategy. Shelter-building spiders, such as Metazygia laticeps (Araneidae), build webs as dynamic traps to capture prey and may optimize capture efficiency while adopting strategies to minimize their exposure to predators by building a shelter and staying inside it most of the time. Prey capture, however, involves leaving the shelter, which may contribute to an increased risk of predation. Individuals may be more likely to take risks when they are in poor nutritional status. In this study, we conducted field experiments to assess support for the hypotheses that M. laticeps spiders with poor nutritional status (i) expose themselves to greater risk of predation during foraging and (ii) invest more silk in different web structures to increase prey capture success. Nutritional state was unrelated to exposure to predation and did not restrict web investment in M. laticeps. However, spiders left the shelter more quickly at night than during the day, regardless of their nutritional state. We suggest that individual’s nutritional state does not determine foraging, and predation risk can affect general activity of spiders depending on foraging period.