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Göteborgs universitets publikationer

Foraging mode of spiders affects risk of predation by birds

Författare och institution:
Bengt Gunnarsson (Institutionen för biologi och miljövetenskap); Kerstin Wiklander (Institutionen för matematiska vetenskaper, matematisk statistik, Chalmers/GU)
Publicerad i:
Biological Journal of the Linnean Society, 115 ( 1 ) s. 58-68
Artikel, refereegranskad vetenskaplig
Sammanfattning (abstract):
Avian insectivores are top predators of arboreal arthropods in different forest ecosystems. The selective effects of bird predation in relation to foraging behaviour in canopy-living spiders were studied in a 2-year field experiment using exclosures in a spruce forest in southern Sweden. Three different hunting strategies – free-hunting, two-dimensional web, three-dimensional web – were included in the analysis. Comparisons of bird predation rate (ratio ln (abundance net-enclosed branch/abundance control)) showed considerable variation between spider groups. Free-hunting spiders suffered most from avian insectivores and predation rate was significantly higher than in spiders with two-dimensional webs. Spiders with three-dimensional webs were exposed to a predation rate in between those of the two other hunting strategies. Generally, the experimental effect was significantly higher in spring samples than in autumn, suggesting a stronger predation pressure in winter. The high variation in susceptibility to predation by insectivores implies that selection on behaviour of spider individuals is strong. Web building in itself is probably part of the protective mechanism, suggesting that webs have dual functions. We conclude that the risk of bird predation is a selective force on foraging behaviour of spiders in a forest canopy system.
Ämne (baseras på Högskoleverkets indelning av forskningsämnen):
Biologiska vetenskaper
Araneae, avian insectivores, differential mortality, hunting strategy, spider webs, spruce canopies
Postens nummer:
Posten skapad:
2015-04-07 14:48
Posten ändrad:
2016-06-28 15:29

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