| Summary: | Their superb ability to fly allows birds to move faster than any other animals: even small passerines fly at top speeds of up to 40-50 km h-1, pigeons can fly about 60-70 km h-1, and birds like swifts are even faster. The distances birds cover during everyday life are considerably longer than those covered by mammals of similar size. Some marine birds venture out for extended foraging trips over the sea; albatrosses ('Diomedea spp.'), for example, may cover several thousands of kilometers. Displaced carrier or homing pigeons ('Columba livia f. domestica') are famous for homing over hundreds of kilometers from unfamiliar sites, and many wild birds also home over considerable distances (for an overview, see R. Wiltschko 1992). Numerous avian species migrate each year to spend the winter in the tropics or in the summer of the opposite hemisphere, covering thousands of kilometers. Two of the most spectacular examples of large migration routes are those of Sooty Shearwaters ('Puffinus griseus') from New Zealand, which wander all over the Pacific Ocean up to Kamchatca and Alaska, and Arctic Terns ('Sterna paradisaea'), which breed in the Arctic tundra and winter on the Antarctic coast, flying around the globe every year. The mechanisms of orientation and navigation of birds must be adapted to these tremendous demands. After a few publications on theoretical considerations about avian navigation and initial preliminary experiments, systematic studies to analyze birds' navigational mechanisms began in the 1950s, when the sun compass was the first orientation mechanism to be identified (Kramer 1950). Our knowledge has increased considerably since then, although a number of open questions remain. Here, we briefly summarize what is known today about birds' navigational mechanisms.
|
|---|