title: The polarization compass dominates over idiothetic cues in path integration of desert ants.
abstract: Desert ants, Cataglyphis, use the sky's pattern of polarized light as a compass reference for navigation. However, they do not fully exploit the complexity of this pattern, rather - as proposed previously - they assess their walking direction by means of an approximate solution based on a simplified internal template. Approximate rules are error-prone. We therefore asked whether the ants use additional cues to improve the accuracy of directional decisions, and focused on 'idiothetic' cues, i.e. cues based on information from proprioceptors. We trained ants in a channel system that was covered with a polarization filter, providing only a single e-vector direction as a directional 'celestial' cue. Then we observed their homebound runs on a test field, allowing full view of the sky. In crucial experiments, the ants were exposed to a cue conflict, in which sky compass and idiothetic information disagreed, by training them in a straight channel that provided a change in e-vector direction. The results indicated that the polarization information completely dominates over idiothetic cues. Two path segments with different e-vector orientations are combined linearly to a summed home vector. Our data provide additional evidence that Cataglyphis uses a simplified internal template to derive directional information from the sky's polarization pattern.
authors.affiliation: Department of Biology, Humboldt-Universität zu Berlin, Invalidenstrasse 43, 10115 Berlin, Germany.
authors.forename: Fleur
authors.initials: F
authors.lastname: Lebhardt
authors.forename: Julja
authors.initials: J
authors.lastname: Koch
authors.forename: Bernhard
authors.initials: B
authors.lastname: Ronacher
mesh_terms: D000818:Animals; D001000:Ants / Q000502:physiology*; D003463:Cues; D003889:Desert Climate; D006702:Homing Behavior / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*; D013028:Space Perception; D013472:Sunlight; D016138:Walking