Avian Navigation: The Crucial Role of the Compass

Roswitha Wiltschko and Wolfgang Wiltschko

Abstract:	Birds use compasses as external reference for navigation tasks in a wide range of spatial dimensions. They possess two compass mechanisms: a magnetic compass that derives directions from the geomagnetic field, and a sun compass that derives directions from sun azimuth with the help of the internal clock; migratory birds may additionally use sunset cues and the stars. This use of external references makes avian navigation a two step process: first, birds determine their home direction as a compass course; second, this course is located with a compass and converted into a heading. To obtain the correct compass course, birds proceed in various ways according to the task to be solved. For navigation at distant sites, the nature of the processes providing the home course vary with age and experience: very young, inexperienced pigeons obtain their home course by recording the direction of their outward journey with the help of a compass, while experienced pigeons that are familiar with the distribution of the navigational factors in their home region determine their home course from local factors with the help of their navigational 'map'. Within their home range, birds appear to proceed in a similar way, using the 'mosaic map' of familiar landmarks to indicate position and with it, the home course. Even within the limited space of a test arena, birds searching for cached food were found to include compass information in their spatial memory. Migratory birds on their first migration rely on innate information on distance and direction to be flown to reach their species-specific winter quarter still unknown to them when they start. The information on direction is genetically coded with respect to an external reference system, and the avian migrants use a compass to convert this course into an actual heading. Compass orientation thus appears to be the basic component of the birds' concept of space.
Published in:	Proceedings of the 60th Annual Meeting of The Institute of Navigation (2004) June 7 - 9, 2004 Dayton Marriott Hotel Dayton, OH
Pages:	148 - 156
Cite this article:	Wiltschko, Roswitha, Wiltschko, Wolfgang, "Avian Navigation: The Crucial Role of the Compass," Proceedings of the 60th Annual Meeting of The Institute of Navigation (2004), Dayton, OH, June 2004, pp. 148-156.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In