Animals that migrate include bar-headed geese, Arctic terns, monarch butterflies, humpback whales, blue whales and zooplankton, according to Silke Nebel of the University of Western Ontario. The bar-tailed godwit, a large shore bird, performs one of the longest non-stop flights, spanning up to nine days.
Migration refers to the seasonal movement of animals, particularly birds, between their breeding and non-breeding sites, states Nebel. It usually involves traveling from one kind of habitat to another. Animals migrate to adapt to the seasonal or geographic differences of resources. Aside from bird migration, there are various types of animal migration, including journeys between eastern and western regions, round-trips encompassing land and ocean, vertical movements through the water column of lakes and oceans, and altitudinal migration up and down mountains.
All major branches of the animal kingdom have migrating animals, including fish, crustaceans, insects, mammals, amphibians and slime moulds, notes Nebel. Zooplankton are the smallest migrants, traveling between 1 to 2 millimeters only. The largest migrants are blue whales, traveling up to 27 meters. The longest mammal migration is performed by humpback whales, which travel up to 8,500 kilometers. The Arctic terns hold the longest round-trip record of 80,000 kilometers, while the monarch butterflies hold the longest insect migration of up to 4,750 kilometers.