Seasonal in the context of Midsummer

Animal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migration in ecology. It is found in all major animal groups, including birds, mammals, fish, reptiles, amphibians, insects, and crustaceans. The cause of migration may be local climate, local availability of food, the season of the year or for mating.

To be counted as a true migration, and not just a local dispersal or irruption, the movement of the animals should be an annual or seasonal occurrence, or a major habitat change as part of their life. An annual event could include Northern Hemisphere birds migrating south for the winter, or wildebeest migrating annually for seasonal grazing. A major habitat change could include young Atlantic salmon or sea lamprey leaving the river of their birth when they have reached a few inches in size. Some traditional forms of human migration fit this pattern.

The North American monsoon, variously known as the Southwest monsoon, the Mexican monsoon, the New Mexican monsoon, or the Arizona monsoon is a pattern of pronounced seasonal increase in thunderstorms and rainfall over large areas of the southwestern United States and northwestern Mexico.

Geographically, the weather pattern is centered over the Sierra Madre Occidental in the Mexican states of Sinaloa, Durango, Sonora and Chihuahua, and typically occurs between June and mid-September. Thunderstorms are fueled by daytime heating and build up during the late afternoon and early evening. Typically, these storms dissipate by late night, and the next day starts out fair, with the cycle repeating daily. The cycle typically loses its energy by mid-September when much drier conditions are reestablished over the region.

Danuvius guggenmosi is an extinct species of great ape that lived 11.6 million years ago during the Middle–Late Miocene in southern Germany. It is the sole member of the genus Danuvius. The area at this time was probably a woodland with a seasonal climate. A male specimen was estimated to have weighed about 31 kg (68 lb), and two females 17 and 19 kg (37 and 42 lb). Both genus and species were described in November 2019.

It is the first-discovered Late Miocene great ape with preserved long bones which could be used to reconstruct the limb anatomy and thus the locomotion of contemporary apes. Its discoverer, paleoanthropologist Madelaine Böhme, says Danuvius had adaptations for both hanging in trees (suspensory behavior) and walking on two legs (bipedalism)—whereas, among present-day great apes, humans are better adapted for the latter and the others the former. Danuvius thus had a method of locomotion unlike any previously known ape called "extended limb clambering", she says, walking directly along tree branches as well as using arms for suspending itself. The last common ancestor between humans and other apes possibly had a similar method of locomotion. However, paleoanthropologist Scott Williams and others say the fragmentary remains do not differ enough from other fossil apes to provide such a clue to the origins of bipedalism.