The effect of reproductive status and situation on locomotor performance and anti-predator strategies in a funnel-web spider

Predation is a major selective force for many species, and the anti-predator strategies most effective for an individual are often shaped by its body condition. In a laboratory experiment, we investigate the influence of reproductive status on the locomotor performance and anti-predator behaviour of female funnel-web spiders Agelenopsis emertoni, both on and off their webs. In general, mated females were slower than unmated females, and a significant amount of variation in the locomotor performance of mated females was explained by their relative reproductive investment (egg case mass/female mass before mating). Regardless of whether they were on or off their webs, mated females were less likely to exhibit flight responses to simulated predator threats than were unmated females. When off their webs, mated females exhibited more aggressive anti-predator responses (i.e. display behaviour), but while on their webs they were more likely to exhibit crypsis or huddling anti-predator responses. Thus, shifts in anti-predator strategy might allow mated females to compensate behaviourally for their reduced locomotor performance.