Wilson R.P. (2001) Beyond rings on birds for determination of movements: Wither the archival tag? ARDEA 89 (1): 231-240

Two methods for determining the movement of birds are discussed; Global Location Sensing (determination of position by consideration of day length and local timing of mid-day) and dead reckoning (calculation of routes by vectors). These are examined for their utility over a number of scales. Work conducted on penguins demonstrates that, although global location sensing is not subject to drift errors, its temporal and spatial resolution makes the system only applicable for large scale movements over at least tens of km. Dead reckoning, however, can be used over scales ranging from tens of kilometers to centimetres. Positions derived from dead reckoning are relatively more accurate the closer they are in time and distance to each other although drift over time can be problematic. The high temporal and spatial resolution of dead reckoning means that animal decisions leading to their movements can be determined and this is examined for penguins over a scales ranging from tens of kilometres to metres. Future work is likely to concentrate on small scale movements in 3 dimensions which, to date, cannot be resolved with other systems