Abstract
Navigation plays an essential role for many animals leading a mobile mode of life, and for central place foragers in particular. One important prerequisite for navigation is the ability to estimate distances covered during locomotion. It has been shown that Cataglyphis desert ants, well-established model organisms in insect navigation, use two odometer mechanisms, namely, stride and optic flow integration. Although both mechanisms are well established, their mode of interaction to build one odometer output remains enigmatic. We tackle this problem by selectively covering the ventral eye parts in Cataglyphis fortis foragers, the eye regions responsible for optic flow input in odometry. Exclusion of optic flow cues was implemented during different sections of outbound and inbound travel. This demonstrated that the two odometers have separate distance memories that interact in determining homing distance. Possible interpretations posit that the two odometer memories (i) take on different relative weights according to context or (ii) compete in a winner-take-all mode. Explanatory values and implications of such interpretations are discussed. We are able to provide a rough quantitative assessment of odometer cue interaction. An understanding of the interaction of different odometer mechanisms appears valuable not only for animal navigation research but may inform discussions on sensor fusion in both behavioural contexts and potential technical applications.
Highlights
Cataglyphis desert ants are accomplished navigators in the barren landscape of North African salt pans, dunes and steppe biotopes [1, 2]
The ants’ major means of orientation is path integration, combining angles steered and distances travelled during outbound travel into a home vector that guides them back to their nest
The optic flow integrator has been charged during outbound travel to 10 m, and this charged optic flow memory appears to have set the stride integrator’s weight to a value normally appropriate for homing
Summary
Cataglyphis desert ants are accomplished navigators in the barren landscape of North African salt pans, dunes and steppe biotopes [1, 2]. During foraging trips, ants may stray from their nest for distances exceeding 10.000 body lengths [3, 4]. The ants’ major means of orientation is path integration, combining angles steered and distances travelled during outbound travel into a home vector that guides them back to their nest. Cataglyphis employs two odometer mechanisms [6], namely, stride and optic flow integration [7,8,9], that appear to represent two independently evolved odometers [9, 10].
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