Why do some animals migrate thousands of miles seasonally?

Animals migrate thousands of miles seasonally primarily to follow food availability and optimal climate conditions. As seasons change, food sources like insects, plants, and fish become scarce in certain regions, so animals travel to areas where resources are abundant. Arctic terns, for example, fly from pole to pole to exploit summer conditions in both hemispheres. Reproduction also drives migration. Many species return to specific breeding grounds where conditions favor offspring survival, whether that means warmer temperatures, safer nesting sites, or reduced predator pressure. Wildebeest follow rainfall patterns to access fresh grass for calving. Essentially, migration is an evolutionary strategy that maximizes survival and reproductive success by exploiting different geographic areas at different times of year.