The cycle of seasons brings changes in the type and amount of foods available to animals in the wild. The changing seasons also bring weather extremes that can threaten animals' survival. Many animals have evolved the ability to respond to these changes by moving from their summer breeding grounds to areas better able to sustain them in the winter. The mass movements of animals over many miles are called migrations. Migrations take place in the spring and autumn. Here in the Northern Hemisphere, animals migrate south in the autumn and north in the spring. Wind currents and food availability combine to create ideal paths for migrating birds to follow. Gateway is located on one of these paths, the Atlantic Flyway. Birds of prey, warblers and shorebirds are some of the types of birds which can be seen in large numbers in Gateway during the spring and autumn migrations.