Animal Migration

Something I hadn't given much thought to and figured only birds do it, but taken from the National Geographic site is as follows:

From the African savannah to the frigid waters off Antarctica, from a Pacific island to the skies of North America, the mass movement of millions of creatures from one place to another is one of the most astonishing of all natural phenomena. But scientists who study the migration of creatures as disparate as the monarch butterfly and the southern elephant seal are motivated by more than just curiosity.

For migratory species, “put simply, migration is crucial for survival,” writes nature journalist and Zoological Society of London fellow Ben Hoare in his 2009 book, Animal Migration: Remarkable Journeys in the Wild. “It has evolved to enable animals to spend their life in two or more different areas, usually because a lack of food or a period of extreme weather makes it impossible to remain in the same location permanently.” Migratory animals also are driven by other imperatives, such as the need to find water or a mate, or to reach a place where they can reproduce.

Scientists also know that increasingly, many of these migratory species are threatened by the spread of human civilization, which increasingly encroaches upon their habitat and sometimes blocks access to the routes that species may have used for thousands of years. Additionally, humans sometimes compete with migratory animals for food or water sources, or destroy them through development.

“Saving the great migrations will be one of the most difficult conservation challenges of the 21st century,” according to ecologist David S. Wilcove, a Princeton University professor and author of the 2008 book No Way Home: The Decline of the World’s Great Animal Migrations. But if we fail to do so, we will pay a heavy price — aesthetically, ecologically, and even economically.” In the 19th and early 20th century, Wilcove notes, human hunting and destruction of habitat in North America drove the migratory passenger pigeon, once one of the most prolific species on the planet, into extinction. But even if species such as the wildebeest and the monarch butterfly manage to survive, he warns, their numbers may be so severely reduced that ecosystems in which they play an important role will be seriously damaged.

Read more: http://channel.nationalgeographic.com/channel/great-migrations-science#ixzz19Qjshegx