title: Backtracking behaviour in lost ants: an additional strategy in their navigational toolkit.
abstract: Ants use multiple sources of information to navigate, but do not integrate all this information into a unified representation of the world. Rather, the available information appears to serve three distinct main navigational systems: path integration, systematic search and the use of learnt information--mainly via vision. Here, we report on an additional behaviour that suggests a supplemental system in the ant's navigational toolkit: 'backtracking'. Homing ants, having almost reached their nest but, suddenly displaced to unfamiliar areas, did not show the characteristic undirected headings of systematic searches. Instead, these ants backtracked in the compass direction opposite to the path that they had just travelled. The ecological function of this behaviour is clear as we show it increases the chances of returning to familiar terrain. Importantly, the mechanistic implications of this behaviour stress an extra level of cognitive complexity in ant navigation. Our results imply: (i) the presence of a type of 'memory of the current trip' allowing lost ants to take into account the familiar view recently experienced, and (ii) direct sharing of information across different navigational systems. We propose a revised architecture of the ant's navigational toolkit illustrating how the different systems may interact to produce adaptive behaviours.
authors: Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia. a.wystrach@sussex.ac.uk
authors: Antoine
authors: A
authors: Wystrach
authors: Sebastian
authors: S
authors: Schwarz
authors: Alice
authors: A
authors: Baniel
authors: Ken
authors: K
authors: Cheng
mesh_terms: D000818:Animals; D001000:Ants / Q000502:physiology*; D003889:Desert Climate; D006702:Homing Behavior; D008568:Memory; D015876:Northern Territory; D009949:Orientation
keywords: ants; backtracking; insect navigation; path integration; systematic search; visual-matching
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