Authors: Sabine Wintergerst Bernhard Ronacher
Publish Date: 2012/02/05
Volume: 198, Issue: 5, Pages: 363-373
Abstract
Desert ants Cataglyphis fortis navigate by means of path integration and perform accurately even in undulating terrain They are able to correctly calculate the ground distance between nest and feeder even if their foraging excursion leads them over corrugated surfaces To compute the respective ground projection when walking over an inclined surface ants must measure its slope with sufficient accuracy—but how they do so is still not understood Using a new behavioural assay that included a negative reinforcement we investigated how well different slopes are discriminated by the ants Ants were trained to visit an elevated feeder via a ramp of fixed inclination five training inclinations were used 0° 15° 30° 45° 60° The ants discriminated a steeper test slope that differed from the training slope by 125° This discrimination performance was found to be constant for training slopes between 0° and 45° Ants trained on a 60° slope however did not discriminate all steeper slopes up to a vertical ascent from the 60° inclination The consequences of this discrimination accuracy for errors in the path integration process are discussedWe thank Mathiijs Boeschoten for his enduring assistance in the field work Fleur Lebhard for help and discussions and in particular Rüdiger Wehner for continuous support many inspiring discussions and helpful comments on the manuscript Gunnar Grah provided the original data of the 2005 experiment We gratefully acknowledge the permission granted by the Tunesian government to carry out these investigations in this beautiful country This work was financed by grants from the DFG Ro 547/101 and the Volkswagen Foundation I/78 574 to BR The experiments comply with the “Principles of animal Care” and with the current German law
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