Examples of animals that migrate include butterflies, land animals, birds and whales. Animals migrate for a wide variety of reasons, such finding food as the weather changes or mating in specific locations year after year. One of the most well known migrations is the complex, extended migration of the Monarch butterfly. The migration cycle lasts longer than the life span of one butterfly, so no single butterfly makes the entire trip from Canada to Mexico and back again.
Salmon migration is notable because they swim upstream for around 1,900 miles back to the river they were born in to spawn. They are able to navigate from salt water to fresh water by tasting the water for different concentrations of mineral salts. The longest nonstop flight during migration is undertaken by the bar-tailed godwit, a bird that breeds in Alaska and then flies for around nine days to reach Australia and New Zealand where it spends the rest of its nonbreeding time.
During migration, animals utilize a combination of visible and invisible cues. Local topography is a visible cue that animals use to chart their migratory course. Animals also use the pattern of polarized light in the sky and the positions of stars in the sky to direct their paths.