While working with the Central Australian desert ant, Melophorus bagoti, about seven years ago I discovered a very neat navigational strategy these ants used. Successfully returning foragers when passively displaced to unfamiliar locations continued to walk in the direction towards where the nest should be, oblivious to the passive displacement. The puzzling find was that ants only walked halfway toward their fictive nest and then began searching. The behaviour was neat and I wrote up a short article reporting this (1), and hypothesised that travelling halfway home is perhaps an optimal strategy for solitary foraging ants that occupy cluttered landmark-rich habitats.
After joining ANU, I met Allen Cheung who was wrapping up his PhD on mathematical modelling on insect navigation. We had brief discussions of how we could tackle this but our discussions didn’t get too far at that point. Subsequently during one of my visits to Bangalore, I was talking about this weird behaviour that I had seen to few of my friends at Koshy’s restaurant over a cup of coffee. A person whom I had never met before joined our table and conversation and after 10 minutes of my long drawn explanations, grabbed a serviette and wrote up an equation with an illustration to explain why this might be the optimal strategy! That was my introduction to Lex Hiby, who I learnt later was instrumental in developing the photo-id software to distinguish individual tigers by their stripes.
Over the next four years, we (mostly Allen) built and expanded on the Lex’s idea to now convincingly show that the chance discovery of ants travelling a specific fraction of the home vector is an optimal strategy and is dependent on the extent of familiar route for animals (2).
1.Narendra A. 2007. Homing strategies of the Australian desert ant Melophorus bagoti I. Proportional path-integration takes the ant half-way home. Journal of Experimental Biology 210: 1798-1803.
2. Cheung A, Hiby L & Narendra A. 2012. Ant navigation: fractional use of the home vector. PLoS ONE 7(11): e50451