title: Self-made shelters protect spiders from predation.
abstract: Many animals modify their environments, apparently to reduce predation risk, but the success of such endeavors, and their impact on the density and distribution of populations, are rarely rigorously demonstrated. We staged a manipulative experiment to assess the effectiveness of self-made shelters by web spiders as protection from natural enemies. Scincid lizards were included or excluded from 21 replicated 200-m(2) plots, and spiders therein were classified as exposed or sheltered, depending on whether they were uncovered in their web or hidden in cocoons, leaves/debris, or burrows. We found that exposed spiders were greatly affected by the presence of predatory scincid lizards, whereas sheltered spiders were not. More specifically, lizards, which forage close to the ground, reduced the abundance of exposed spiders by two-thirds but had no effect on the abundance of sheltered spiders. Sheltered spiders were able to avoid predation and share space with lizards, suggesting that shelter construction is a mechanism for reducing predation risk and has important population consequences.
authors.affiliation: School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia. carryn.manicom@jcu.edu.au
authors.forename: Carryn
authors.initials: C
authors.lastname: Manicom
authors.forename: Lin
authors.initials: L
authors.lastname: Schwarzkopf
authors.forename: Ross A
authors.initials: RA
authors.lastname: Alford
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Schoener
mesh_terms: D000818:Animals; D020387:Food Chain; D008116:Lizards / Q000502:physiology*; D011235:Predatory Behavior; D013112:Spiders / Q000502:physiology*
references.citation: Science. 2001 Nov 30;294(5548):1923-6
references.pmid: 11729317
references.citation: Science. 1990 Nov 9;250(4982):811-4
references.pmid: 17759974
references.citation: Am Nat. 2000 Feb;155(2):141-153
references.pmid: 10686157
references.citation: Oecologia. 1989 Apr;79(1):136-139
references.pmid: 28312824
references.citation: Am Nat. 2001 Mar;157(3):262-81
references.pmid: 18707289
references.citation: Oecologia. 1984 Oct;64(2):160-162
references.pmid: 28312332
references.citation: Science. 1983 Jan 14;219(4581):185-7
references.pmid: 17841687