Migration in mammals occurs for various reasons such as following food sources or more favorable living conditions. Some key mammal migrations discussed in the document include wildebeest in the Serengeti that travel nearly 3,000km annually following rains, bearded pigs in Southeast Asia that may travel up to 600km following seasonal fruit supplies, and caribou in Canada and Alaska with the Porcupine herd traveling 640km between summer and winter ranges. The document also briefly outlines migrations of white-eared kob, Burchell's zebra, straw-colored bats, Asian elephants, chiru antelope, lemmings, and saiga antelope.