Animal Navigation: Pitfalls and Remedies

Allen Cheung, Shaowu Zhang, Christian Sticker, and Mandyam V. Srinivasan

Abstract:	In principle, there are two kinds of strategies for navigating a straight course. One is to orient by means of an external directional reference, such as a compass. The other is to infer body rotations from internal sensory information only. In either case, animals would make errors during navigation due to the unavoidable presence of biological noise at the sensory, processing or motor levels. We show here, however, that the two strategies differ dramatically in their susceptibility to noise. While a compass-based strategy will enable an animal to travel arbitrarily far away from its starting point, a compassless strategy will not. Our findings indicate that, except for very short journeys, an external directional reference - some form of compass - is indispensable for ensuring progress away from home. This limitation must place significant constraints on the evolution of biological navigation systems. On the basis of these findings, we postulate that any biologically plausible path integrator must be made up of a compass and an odometer. In evolutionary terms, there must have been immense selective pressure to evolve sensory apparatus which can yield allocentric direction information. Therefore, despite some of the advantages of developing idiothetic senses for various tasks, navigation or otherwise, it would seem that a compass has far greater biological value than any idiothetic sensory apparatus in the context of navigation.
Published in:	Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007) April 23 - 25, 2007 Royal Sonesta Hotel Cambridge, MA
Pages:	270 - 279
Cite this article:	Cheung, Allen, Zhang, Shaowu, Sticker, Christian, Srinivasan, Mandyam V., "Animal Navigation: Pitfalls and Remedies," Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007), Cambridge, MA, April 2007, pp. 270-279.
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