title: Evidence of bird dropping masquerading by a spider to avoid predators.
abstract: Masquerading comes at various costs and benefits. The principal benefit being the avoidance of predators. The orb-web spider Cyclosa ginnaga has a silver body and adds a white discoid-shaped silk decoration to its web. The size, shape and colour of C. ginnaga's body resemble, when viewed by the human eye against its decoration, a bird dropping. We therefore hypothesized that their body colouration might combine with its web decoration to form a bird dropping masquerade to protect it from predators. We measured the spectral reflectance of: (i) the spider's body, (ii) the web decoration, and (iii) bird droppings, in the field against a natural background and found that the colour of the spider bodies and decorations were indistinguishable from each other and from bird droppings when viewed by hymentopteran predators. We monitored the predatory attacks on C. ginnaga when the spider's body and/or its decorations were blackened and found that predator attack probabilities were greater when only the decorations were blackened. Accordingly, we concluded that C. ginnaga's decoration and body colouration forms a bird dropping masquerade, which reduces its probability of predation.
authors.affiliation: 1] Department of Life Science, National Chung-Hsin University, Taichung 40227, Taiwan [2] Taiwan Endemic Species Research Institute, Nantou 55244, Taiwan.
authors.forename: Min-Hui
authors.initials: MH
authors.lastname: Liu
authors.affiliation: 1] Department of Life Science, Tunghai University, Taichung 40704, Taiwan [2].
authors.forename: Sean J
authors.initials: SJ
authors.lastname: Blamires
authors.affiliation: Department of Life Science, Tunghai University, Taichung 40704, Taiwan.
authors.forename: Chen-Pan
authors.initials: CP
authors.lastname: Liao
authors.affiliation: 1] Department of Life Science, National Chung-Hsin University, Taichung 40227, Taiwan [2] Department of Life Science, Tunghai University, Taichung 40704, Taiwan.
authors.forename: I-Min
authors.initials: IM
authors.lastname: Tso
mesh_terms: D000818:Animals; D001717:Birds; D003116:Color; D003118:Color Perception / Q000502:physiology; D004924:Escape Reaction / Q000502:physiology*; D005243:Feces; D007100:Imitative Behavior / Q000502:physiology*; D007313:Insecta / Q000502:physiology*; D011235:Predatory Behavior / Q000502:physiology*; D013112:Spiders / Q000033:anatomy & histology / Q000502:physiology*