Regular travelling of birds between different regions inhabited by them at different times of year. Normally one region is the breeding area and the other is better suited to support them in the other season(s). Migration can be seen as the alternative to adapting to the changeable conditions of the breeding region throughout the year as shown by sedentary (residential) species. Therefore it is mostly seen among species breeding in the higher latitudes and there are great differences in the extent of the movements and in the degree to which these are definite and regular.

Alternative forms for migration : migrations, migratory.