Why Do Bird Migrate?

The British Isles have a wide range of physical regions which encourages a tremendous diversity of birdlife. More than 200 species of birds breed or winter here.

The most important reason why birds undertake migratory flights is simple. Water cold reduces their food supply so much that they are in the real danger of stravation.

They need to seek warmer countries if they are to survive. Birds become migratory only to ensure that more individuals of a species will survive, despite the risk of being blown off course during their travels, than if they stay stay to eke out a precarious living.

If the risks of migration outweigh those of wintering, the species will be sedentary, but for some species, such as the lapwing and the song trush, risks and disadvantages are so finely balanced that neither pattern dominates.

Time of departure of migratory birds is determined by the weather, wind directions and strength being more important to the birds than changes in temperature.

Many birds regularly return to the same small area of territory and ringed birds returning have been recorded passing the same locality on the same date in consecutive years.

Birds are able to navigate by means of the sun and stars, but how they do this has not yet been fully established.

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