Effects of migration on birds and human introduction
Answers
Examples of long distance bird migration routes.
Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding and wintering grounds. Many species of birdmigrate. Migration carries high costs in predation and mortality, including from hunting by humans, and is driven primarily by availability of food. It occurs mainly in the northern hemisphere, where birds are funneled on to specific routes by natural barriers such as the Mediterranean Sea or the Caribbean Sea.
Migration of species such as storks, turtle doves, and swallows was recorded as many as 3,000 years ago by Ancient Greek authors, including Homer and Aristotle, and in the Book of Job. More recently, Johannes Leche began recording dates of arrivals of spring migrants in Finland in 1749, and modern scientific studies have used techniques including bird ringing and satellite tracking to trace migrants. Threats to migratory birds have grown with habitat destruction especially of stopover and wintering sites, as well as structures such as power lines and wind farms.
The Arctic tern holds the long-distance migration record for birds, travelling between Arctic breeding grounds and the Antarctic each year. Some species of tubenoses (Procellariiformes) such as albatrosses circle the earth, flying over the southern oceans, while others such as Manx shearwaters migrate 14,000 km (8,700 mi) between their northern breeding grounds and the southern ocean. Shorter migrations are common, including altitudinal migrations on mountains such as the Andes and Himalayas.
The timing of migration seems to be controlled primarily by changes in day length. Migrating birds navigate using celestial cues from the sun and stars, the earth's magnetic field, and mental maps.
Birds migrate in search of food; breeding ground; and warmer weather. Scientist believe that birds navigate their way through Earth's magnetic fields. This helps birds navigate with pinpoint accuracy. Unlike birds, human migration and settlement is not subject to Earth's magnetic field rather by need for basic needs (shelter, food amd water). As human beings are arguably the apex predetor on Earth, their population grows rapidly as it is seldom unchecked (only by diseases and war). This increases their settlement. With their ability to utilize Earth's elements they end up clearing birds traditional breeding and feeding grounds. The birds adapt to living with human beings because their activities bring about free recources; in terms of food and water. The birds adapt to newer feeding patterns but will still maintain their migration pattern.
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