title: The confusion effect when attacking simulated three-dimensional starling flocks.
abstract: The confusion effect describes the phenomenon of decreasing predator attack success with increasing prey group size. However, there is a paucity of research into the influence of this effect in coherent groups, such as flocks of European starlings (Sturnus vulgaris). Here, for the first time, we use a computer game style experiment to investigate the confusion effect in three dimensions. To date, computerized studies on the confusion effect have used two-dimensional simulations with simplistic prey movement and dynamics. Our experiment is the first investigation of the effects of flock size and density on the ability of a (human) predator to track and capture a target starling in a realistically simulated three-dimensional flock of starlings. In line with the predictions of the confusion effect, modelled starlings appear to be safer from predation in larger and denser flocks. This finding lends credence to previous suggestions that starling flocks have anti-predator benefits and, more generally, it suggests that active increases in density in animal groups in response to predation may increase the effectiveness of the confusion effect.
authors.affiliation: School of Biological Sciences, University of Bristol, Life Sciences Building, Bristol BS8 1TQ, UK; School of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TH, UK.
authors.forename: Benedict G
authors.identifier: 0000-0001-6762-7738
authors.initials: BG
authors.lastname: Hogan
authors.affiliation: Groningen Institute for Evolutionary Life Sciences , University of Groningen , Groningen, 9747 AG , The Netherlands.
authors.forename: Hanno
authors.initials: H
authors.lastname: Hildenbrandt
authors.affiliation: School of Experimental Psychology , University of Bristol , 12a Priory Road, Bristol BS8 1TH , UK.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Scott-Samuel
authors.affiliation: School of Biological Sciences , University of Bristol , Life Sciences Building, Bristol BS8 1TQ , UK.
authors.forename: Innes C
authors.initials: IC
authors.lastname: Cuthill
authors.affiliation: Groningen Institute for Evolutionary Life Sciences , University of Groningen , Groningen, 9747 AG , The Netherlands.
authors.forename: Charlotte K
authors.initials: CK
authors.lastname: Hemelrijk
keywords: confusion effect; realistic three-dimensional computer simulations; starling flocking; target tracking