Orientation and navigation of migrating birds

Resumo

The question of how migrating birds find their way to winter quarters and back has fascinated humans since the beginning of scientific research into avian biology. Migrating birds have been shown to possess compass systems that allow them to select and maintain certain compass directions. Three such systems are known, solar, stellar and magnetic. Their details are not quite clear and need further research. Hierarchy and interaction of compass systems of migrating birds are poorly studied; different species may vary in this respect. During migration, birds learn to use maps that make true navigation possible, i.e. to detect their position relatively to the goal of movement. The physical nature of navigational maps is an object of intensive research; currently the most promising concepts are the geomagnetic and possibly olfactory maps. A significant contribution to the study of formation of navigational maps was made by Soviet/Russian researchers, whose work was published in Zoologicheskii Zhurnal (Sokolov et al., 1984). Migrating birds have no innate map, and first-autumn individuals reach their species-specific wintering areas by using compass sense and counting time that should be spent moving in certain genetically fixed directions. However, in recent years more and more data surface that suggest that juveniles (maybe not of all species) do have some mechanism of controlling their position on the migratory route that allows them to compensate for errors of the spatio-temporal programme of migration.