Foraging mode of spiders affects risk of predation by birds

摘要: Avian insectivores are top predators of arboreal arthropods in different forest ecosystems. The selective effects bird predation relation to foraging behaviour canopy-living spiders were studied a 2-year field experiment using exclosures spruce southern Sweden. Three hunting strategies – free-hunting, two-dimensional web, three-dimensional web included the analysis. Comparisons rate (ratio ln (abundance net-enclosed branch/abundance control)) showed considerable variation between spider groups. Free-hunting suffered most from avian and was significantly higher than with webs. Spiders webs exposed those two other strategies. Generally, experimental effect spring samples autumn, suggesting stronger pressure winter. high susceptibility by implies that selection on individuals is strong. Web building itself probably part protective mechanism, have dual functions. We conclude risk force canopy system.