title: Turn costs change the value of animal search paths.
abstract: The tortuosity of the track taken by an animal searching for food profoundly affects search efficiency, which should be optimised to maximise net energy gain. Models examining this generally describe movement as a series of straight steps interspaced by turns, and implicitly assume no turn costs. We used both empirical- and modelling-based approaches to show that the energetic costs for turns in both terrestrial and aerial locomotion are substantial, which calls into question the value of conventional movement models such as correlated random walk or Lévy walk for assessing optimum path types. We show how, because straight-line travel is energetically most efficient, search strategies should favour constrained turn angles, with uninformed foragers continuing in straight lines unless the potential benefits of turning offset the cost.
authors.affiliation: Swansea Lab for Animal Movement, Biosciences, College of Science, Swansea University, Singleton Park, Swansea, SA2 8PP, Wales, UK. r.p.wilson@swansea.ac.uk
authors.forename: R P
authors.initials: RP
authors.lastname: Wilson
authors.forename: I W
authors.initials: IW
authors.lastname: Griffiths
authors.forename: P A
authors.initials: PA
authors.lastname: Legg
authors.forename: M I
authors.initials: MI
authors.lastname: Friswell
authors.forename: O R
authors.initials: OR
authors.lastname: Bidder
authors.forename: L G
authors.initials: LG
authors.lastname: Halsey
authors.forename: S A
authors.initials: SA
authors.lastname: Lambertucci
authors.forename: E L C
authors.initials: EL
authors.lastname: Shepard
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D017753:Ecosystem; D005247:Feeding Behavior; D006801:Humans; D008954:Models, Biological; D009043:Motor Activity
keywords: Brownian motion; Lévy walk; correlated random walk; energetics; movement costs; search strategy; turn angle; turn radius