To a highly mobile species like humans, the fact that other animals relocate their families – or entire populations – isn’t a big surprise. We know historical migrations have been the norm, though the fossil record shows that generally these changes happened at a snail’s pace.
The “Great American Interchange” in which northern animals spread southward and South American critters expanded north during the Pliocene Epoch, took a million years. Give or take a few, I assume. [Read more…] about Northern Tree Migrations: Nature on the Move