Trail geometry gives polarity to ant foraging networks

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Pheromone trails are used by many ants to guide foragers between nest and food1,2,3,4. But how does a forager that has become displaced from a trail know which way to go on rejoining the trail? A laden forager, for example, should walk towards the nest. Polarized trails would enable ants to choose the appropriate direction, thereby saving time and reducing predation risk. However, previous research has found no evidence that ants can detect polarity from the pheromone trail alone3,5,6,7. Pharaoh's ants (Monomorium pharaonis) produce elaborate trail networks throughout their foraging environment8. Here we show that by using information from the geometry of trail bifurcations within this network, foragers joining a trail can adaptively reorientate themselves if they initially walk in the wrong direction. The frequency of correct reorientations is maximized when the trail bifurcation angle is approximately 60 degrees, as found in natural networks. These are the first data to demonstrate how ant trails can themselves provide polarity information. They also demonstrate previously unsuspected sophistication in the organization and information content of networks in insect societies.

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Figure 1: Pheromone trail networks of Pharaoh's ants on a smoked glass surface.
Figure 3: Outcomes of individual trail following tests using straight (0°) and bifurcating (30–120°) trail sections.
Figure 2: Experimental set-up used to form straight trails and assembly of trail bifurcations.


  1. 1

    Schöne, H. Spatial Orientation (Princeton Univ. Press, Princeton, 1984)

  2. 2

    Camazine, S. et al. Self-organisation in Biological Systems 217–255 (Princeton Univ. Press, New Jersey, 2001)

  3. 3

    Carthy, J. D. The orientation of two allied species of British ant. II. Odour trail laying and following in Acanthomyops (Lasius) fuliginosus. Behaviour 3, 304–318 (1951)

  4. 4

    Hölldobler, B. & Wilson, E. O. The Ants (Belknap Press, Harvard Univ., Cambridge, Massachusetts, 1990)

  5. 5

    Carthy, J. D. Odour trails of Acanthomyops fuliginosus. Nature 166, 154 (1950)

  6. 6

    Sudd, J. H. An Introduction to the Behaviour of Ants Ch. 6 (Edward Arnold, London, 1967)

  7. 7

    Wilson, E. O. Chemical communication among workers of the fire ant, Solenopsis saevissima. I. The organisation of mass foraging. Anim. Behav. 10, 134–164 (1962)

  8. 8

    Sudd, J. H. The foraging method of Pharaoh's ant, Monomorium pharaonis (L.). Anim. Behav. 8, 67–75 (1960)

  9. 9

    Banks, A. N. & Syrgley, R. B. Orientation by magnetic field in leaf-cutter ants, Atta colombica (Hymenoptera: Formicidae). Ethology 109, 835–846 (2003)

  10. 10

    Carthy, J. D. The orientation of two allied species of British ant. I. Visual direction finding in Acanthomyops (Lasius) niger. Behaviour 3, 275–303 (1951)

  11. 11

    Aron, S., Beckers, R., Deneubourg, J. & Pasteels, J. M. Memory and chemical communication in the orientation of two mass-recruiting ant species. Insectes Soc. 40, 369–380 (1993)

  12. 12

    Fowler, H. G. Foraging trails of leaf-cutting ants. Proc. NY Entomol. Soc. 86, 132–136 (1978)

  13. 13

    Holldobler, B. Home range orientation and territoriality in harvester ants. Proc. Natl Acad. Sci. USA 71, 3274–3277 (1974)

  14. 14

    Quinet, Y. & Pasteels, J. M. Spatiotemporal evolution of the trail network in Lasius fuliginosus (Hymenoptera, Formicidae). Belg. J. Zool. 121, 55–72 (1991)

  15. 15

    Rettenmeyer, C. W. Behavioral studies of army ants. Univ. Kansas Sci. Bull. 44, 281–465 (1963)

  16. 16

    Acosta, F. J., Lopez, F. & Serrano, J. M. Branching angles of ant trunk trails as an optimization cue. J. Theor. Biol. 160, 297–310 (1993)

  17. 17

    Fourcassié, V. & Deneubourg, J. L. The dynamics of collective exploration and trail-formation in Monomorium pharaonis: experiments and model. Physiol. Entomol. 19, 291–300 (1994)

  18. 18

    Feynman, R. Surely You Are Joking, Mr Feynman? (Norton, New York, 1985)

  19. 19

    Barker, S. B., Cumming, G. & Horsfield, K. Quantitative morphometry of the branching structure of trees. J. Theor. Biol. 40, 33–43 (1973)

  20. 20

    Leopold, L. B. Trees and streams: the efficiency of branching patterns. J. Theor. Biol. 31, 339–354 (1971)

  21. 21

    Thompson, D. W. On Growth and Form (Cambridge Univ. Press, Cambridge, 1917)

  22. 22

    West, G. B., Brown, J. H. & Enquist, B. J. A general model for the origin of allometric scaling laws in biology. Science 276, 122–126 (1997)

  23. 23

    West, G. B., Brown, J. H. & Enquist, B. J. A general model for the structure and allometry of plant vascular systems. Nature 400, 664–667 (1999)

  24. 24

    Dussutour, A., Fourcassié, V., Helbing, D. & Deneubourg, J. Optimal traffic organization in ants under crowded conditions. Nature 428, 70–73 (2004)

  25. 25

    Tennant, L. E. & Porter, S. D. Comparison of diets of two fire ant species: solid and liquid components. J. Entomol. Sci. 26, 450–465 (1991)

  26. 26

    Jeanson, R., Ratnieks, F. L. W. & Deneubourg, J. L. Pheromone trail decay rates on different substrates in the Pharaoh's ant, Monomorium pharaonis. Physiol. Entomol. 28, 192–198 (2003)

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We thank K. Boomsma, A. Bourke, V. Fourcassié, A. Hart, L. Keller, S. Martin and G. Theraulaz for discussions and comments on the manuscript. We also thank P. Mitchell for statistical advice. This work was funded by the EPSRC and British Telecom.

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Correspondence to Duncan E. Jackson.

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The authors declare that they have no competing financial interests.

Supplementary information

Supplementary Table 1

This table shows reorientation results for fed and unfed foragers when placed at the ends of a Y-shaped pheromone trail (angle 30-120 degrees) representing a bifurcating foraging trail leading from the nest or a straight trail. (DOC 90 kb)

Supplementary Table Legend

Additional information to accompany the above Supplementary Table. (DOC 20 kb)

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Jackson, D., Holcombe, M. & Ratnieks, F. Trail geometry gives polarity to ant foraging networks. Nature 432, 907–909 (2004) doi:10.1038/nature03105

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