Migration

Some birds and mammals move over long distances to survive a difficult season. They do this to avoid the extreme temperatures in which they cannot live or to avoid the temporary lack of food and water. Many small insect-eating birds, such as swallows and warblers, migrate to warmer climates in late summer or autumn. They return again in spring. Swifts, which are common in cities all over the world, will migrate between the northern countries and the tropics. In Canada, the swifts fly south to the Amazon basin in South America. In Europe, they fly to East Africa. In Japan, they migrate to Australia for the winter.

The European stork migrates from its summer breeding grounds in north-west Europe to tropical Africa, south of Sahara desert. The stork flies by one of two routes: either by the Straits of Gibraltar in Spain or by the Dardanelles in Turkey. This means that they avoid flying over the Mediterranean Sea. Either way, the storks have to fly 12000 km.

About 4000 species of birds are known to migrate between their winter quarters and their summer quarters. Some species only fly a few hundred kilometres but other species are long distance voyagers. The snow goose migrates 5000 km between the north of Canada and the south of the United States.

Migrations are not always from cold latitudes to the tropics. The barnacle goose migrates to Scotland for the winter and flies back to Norway in the spring. It spends its summers in the far north. Eighteen species of geese fly to the Arctic in the spring. There the vegetation grows rapidly and it is very nutritious. These geese raise their offspring in the short Arctic summer before returning to the south in the autumn.

© Paul Billiet and Shirley Burchill 2009