latitudes spend the winter at lower latitudes), and many show the alternative, chain migration, where populations 'slide' more evenly north and south without reversing the order.

Within a population, it is common for different ages and/or sexes to have different patterns of timing and distance. Female chaffinches Fringilla coelebs in Eastern Fennoscandia migrate earlier in the autumn than males do and the European tits of genera Parus