title: Stellar performance: mechanisms underlying Milky Way orientation in dung beetles.
abstract: Nocturnal dung beetles (Scarabaeus satyrus) are currently the only animals that have been demonstrated to use the Milky Way for reliable orientation. In this study, we tested the capacity ofS. satyrusto orient under a range of artificial celestial cues, and compared the properties of these cues with images of the Milky Way simulated for a beetle's visual system. We find that the mechanism that permits accurate stellar orientation under the Milky Way is based on an intensity comparison between different regions of the Milky Way. We determined the beetles' contrast sensitivity for this task in behavioural experiments in the laboratory, and found that the resulting threshold of 13% is sufficient to detect the contrast between the southern and northern arms of the Milky Way under natural conditions. This mechanism should be effective under extremely dim conditions and on nights when the Milky Way forms a near symmetrical band that crosses the zenith. These findings are discussed in the context of studies of stellar orientation in migratory birds and itinerant seals.This article is part of the themed issue 'Vision in dim light'.
authors.affiliation: Lund Vision Group, Department of Biology, Lund University, 223 62 Lund, Sweden james.foster@biol.lu.se.
authors.forename: James J
authors.identifier: http://orcid.org/0000-0002-4444-2375
authors.initials: JJ
authors.lastname: Foster
authors.affiliation: Lund Vision Group, Department of Biology, Lund University, 223 62 Lund, Sweden.
authors.forename: Basil
authors.initials: B
authors.lastname: El Jundi
authors.affiliation: Lund Vision Group, Department of Biology, Lund University, 223 62 Lund, Sweden.
authors.forename: Jochen
authors.initials: J
authors.lastname: Smolka
authors.affiliation: Lund Vision Group, Department of Biology, Lund University, 223 62 Lund, Sweden.
authors.forename: Lana
authors.initials: L
authors.lastname: Khaldy
authors.affiliation: Lund Vision Group, Department of Biology, Lund University, 223 62 Lund, Sweden.
authors.forename: Dan-Eric
authors.initials: DE
authors.lastname: Nilsson
authors.affiliation: School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Wits 2050, South Africa.
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Byrne
authors.affiliation: Lund Vision Group, Department of Biology, Lund University, 223 62 Lund, Sweden.|School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Wits 2050, South Africa.
authors.forename: Marie
authors.initials: M
authors.lastname: Dacke
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000502:physiology*; D003463:Cues; D008027:Light; D000072458:Orientation, Spatial
keywords: sky compass; star; straight-line orientation; vision