Six of the focal species either no longer migrated at all or, in a couple cases, no longer survived in the wild.
The images have become iconic: wildebeest forging a crocodile-inhabited river, caribou breaking through snow fields, Saiga running over tall grass. Despite such images of plenty, migrations are declining across the world, and in six cases have disappeared entirely.
A new study published in Endangered Species Research looked at the state of just these kinds of migrations, focusing on 24 large ungulate species (hoofed animals) known for their migratory patterns. Researchers included some well-known species, such as caribou, American bison, elk, zebra, wildebeest, chiru (or Tibetan antelope), and saiga.
"Conservation science has done a poor job in understanding how migrations work, and as a result many migrations have gone extinct," explains Grant Harris of the Center for Biodiversity and Conservation at the American Museum of Natural History, first author of the paper. "Fencing, for example, blocks migratory routes and reduces migrant's access to forage and water. Migrations can then stop, or be shortened, and animal numbers plummet."
Pronghorn antelope migration. Photo by: J. Berger.
According to the study, all 24 focal species lost migration routes and suffered population declines. Many of these migrations have been little studied. While Africa includes the most large-scale migrations, the authors found that three migrating species had no publications on their population status. In Eurasia half of the migratory species had been largely ignored by science.
Mongabay.com is an environmental science and conservation news web site.
