To migrate means to move from one place to another, sometimes part of a back-and-forth pattern, and sometimes to stay.
When we think of the word migrate we think of movement from place to place. Sometimes that movement is seasonal, as when birds migrate north in summer and south in winter. But sometimes a person or group will migrate from one place to another with the intention of settling there. In both cases, there is a definite shift in locales, one temporary, the other permanent.