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Archive for November, 2009

I just got back from a fantastic summer school on animal navigation. This was the 8th consecutive year of this school and was organised by Allen Cheung at The University of Queensland, QBI, Brisbane. The summer school has always maintained a high teacher to student ratio & was no different this time around. We had several fantastic lectures and tours to labs. Here are a few highlights:
  • Magnetoreception in birds from Roswitha Wiltschko and Wolfgang Wiltschko. They gave a stunning overview of the field, the current controversies, and ideas of how to determine if your favourite animal uses magnetic field for orientation or positional information.
  • Medium-scale navigation of bats by Nachum Ulanovsky. The route following behaviour these bats from Israel exhibit is very different from what we currently know from birds. This was easily the most hotly discussed/debated talk over the whole week. Keep an eye out when this gets published sometime next year!
  • Janet Wiles, Director of Thinking Systems introduced us to her work on how they get robots to associate spaces with languages. Very cool!
  • Mandyam Srinivasan took us along the journey of the discovery of use of optic flow for distance estimation by honeybees. Also highlighted were the challenges bees face in making the perfect landing on vertical or horizontal surfaces.
  • Some pretty cool virtual reality work by Dan Angus and Allen Cheung where they created 3-D arenas and got us to think about image differences in a multitude of situations. This will be very crucial in light of the recent work on image differences in panoramic images in several animals.
  • Jochen Zeil gave us an overview of knowledge base of insects with great emphasis on the the different ways insects use landmarks.
  • Justin Marshall explained to us know why we know very little about navigation in marine environments, while we drooled over his study sites and study species (mantis shrimp, cuttlefish).
Jochen and I got two practical sessions running:
  • from the human navigation experiments using differential GPS all of us became acutely aware of the difficulty of walking in a straight line while blindfolded and ears plugged. Kudos to the desert ants!
  • in the ant navigation practical we discovered that Rhytidoponera metallica mostly rely on visual landmark information for homing but in certain contexts path integrates using a celestial compass.
I am already looking forward for the next year’s summer school!

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Ants use vector or visual information to head to a particular goal. To cope with disturbances or ‘errors’ arising from their global vector, they use landmarks either as familiar beacons to guide their entire journey or/and to pinpoint a specific location. Studies on Formica and Melophorus bagoti have shown the ants correct for any local displacements along the route which led several authors (me included!) to predict that ants use panoramic cues for homing.

Till date, however, no studies have explicitly tested this. Paul and Ken do exactly this in their recent article in Current Biology. By mimicking the skyline profile using walls of differing dimensions, they provide the best experimental evidence for the use of panoramic skyline not only for ants, but also for any insect. They show the ant’s orientation in the natural scene is similar to the skyline profile they provided. They then rotated the skyline profile and found the ants change their orientation to match the rotation of the panorama.

Further reading:
Paul Graham & Ken Cheng. 2009. Ants use the panoramic skyline as a visual cue during navigation. Current Biology 19: R935 – R937

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