Bird migration
Seasonal movement of birds between breeding and wintering grounds.
Bird migration is the regular seasonal movement of birds between breeding and wintering grounds, occurring twice a year, typically between northern and southern regions. This journey carries inherent risks, including predation and other hazards en route. The Arctic tern holds the record for the longest migration, traveling between Arctic breeding grounds and the Antarctic each year. Some tubenoses, like albatrosses, circle the Earth over southern oceans, while Manx shearwaters migrate between northern breeding areas and the Southern Ocean. Shorter migrations are more common, including altitudinal movements on mountains such as the Andes and Himalayas. The timing of migration is primarily controlled by changes in day length, and birds navigate using celestial cues from the sun and stars, the Earth’s magnetic field, and mental maps.
Historically, bird migration has been observed for millennia. In the Pacific, traditional land-finding techniques of Micronesians and Polynesians suggest migration was interpreted for over 3,000 years; in Samoan tradition, the god Tagaloa sent his daughter Sina as a bird, Tuli, to find dry land, referring to land-finding waders like the Pacific golden plover. Ancient Greeks recognized seasonal bird movements; Aristotle noted cranes traveling from Scythia to the Nile, though he believed swallows hibernated. This hibernation belief persisted into the late 19th century, with Elliott Coues listing 182 papers on swallow hibernation. Even Gilbert White, in 1789, considered the possibility of torpid swallows but doubted migration. Only by the late 18th century was migration widely accepted. In 1822, a white stork found in Mecklenburg with an arrow from central African hardwood—a Pfeilstorch—provided early evidence of long-distance migration.
Approximately 1,800 of the world’s 10,000 bird species are long-distance migrants. The primary motivation for migration is food; longer northern summer days allow diurnal birds to feed young and produce larger clutches. These advantages offset the high stress, physical exertion, and predation risks, such as those exploited by Eleonora’s falcon, which times its late breeding to prey on southbound passerine migrants.
- longest_distance_migrant
- Arctic tern
- record_distance
- Arctic breeding grounds to Antarctic each year
- primary_control_of_timing
- Changes in day length
- navigation_methods
- Celestial cues from Sun and stars, Earth's magnetic field, mental maps
Lore & Background
In Samoan tradition, Tagaloa sent his daughter Sina to Earth as a bird, Tuli, to find dry land, with tuli referring to land-finding waders, often the Pacific golden plover. Only at the end of the eighteenth century was migration accepted as the explanation for winter bird disappearance. Bird migration is a twice-yearly seasonal movement between breeding and wintering grounds, typically between northern and southern regions, carrying inherent risks such as predation. The Arctic tern holds the record for the longest migration, traveling between Arctic breeding grounds and the Antarctic each year. Some tubenoses, like albatrosses, circle the Earth over southern oceans, while Manx shearwaters migrate between northern breeding grounds and the Southern Ocean. Shorter migrations, including altitudinal movements on mountains like the Andes and Himalayas, are common. Migration timing is primarily controlled by changes in day length. Birds navigate using celestial cues from the Sun and stars, the Earth’s magnetic field, and mental maps. Historical understanding evolved slowly: Aristotle recorded cranes traveling from Scythia to the Nile, but believed swallows hibernated, a view persisting into the late 1800s. In 1822, a white stork found in Mecklenburg with an African arrow provided early evidence of long-distance stork migration. The primary motivation for migration is food; longer northern summer days allow diurnal birds to feed young more and produce larger clutches. These advantages offset the physical exertion and heightened predation risks, such as those exploited by Eleonora’s falcon, which times its breeding to prey on southbound passerine migrants.
Reader's Guide
Bird migration is a key biological phenomenon involving regular seasonal movement, often north and south, between breeding and non-breeding areas. The primary motivation appears to be food availability, with longer northern summer days allowing extended feeding of young. These advantages offset high stress, physical exertion, and risks such as predation—exemplified by Eleonora's falcon, which times its breeding to feed on southbound passerine migrants. Partial migration occurs within species, with some populations migratory and others sedentary. Migration patterns include leap-frog and chain migration, and most birds migrate in flocks, which reduces energy costs; geese in V formation conserve 12–20% energy. The timing is controlled primarily by day length, and navigation uses celestial cues, Earth's magnetic field, and mental maps. The Arctic tern holds the long-distance record, traveling between Arctic and Antarctic each year. Understanding migration has grown from ancient observations to modern tracking, but the phenomenon remains a subject of ongoing study.
Did You Know?
- The Arctic tern holds the long-distance migration record, traveling between Arctic breeding grounds and the Antarctic each year.
- Eleonora's falcon breeds on Mediterranean islands and coordinates its late breeding season with the autumn passage of southbound passerine migrants, which it feeds to its young.
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