Whales, eels, salmon and lots of other fish migrate to and from their breeding grounds. Herd animals, such as elephants and wildebeests migrate to where water and food is most plentiful. Lemmings get an urge to move when local conditions become too crowded. Whether you're big or small, it takes a lot of effort to move long distances. It's even tougher if you don't have a backbone.
Most invertebrates move short distances compared to vertebrates.
A journey from one part of a bay to another may constitute a migration for a clam. However, some insects migrate distances as long or nearly as long as do birds. Locusts in Asia and Africa, for instance, may migrate in great swarms for hundreds of miles. Perhaps even more amazing is the migration of some butterflies. These common butterflies are a beautiful orange or gold color having black stripes and white dots on the tops of their wings.