Illinois State Museum

migration graphic
The Wapiti, or Elk, migrated.

Adaptation, Migration, and Extinction

Plants and animals responded in different ways to the warming climate near the end of the Wisconsin Glacial Episode (14,000 years ago).

Adaptation: Many species of mammals, birds, reptiles, amphibians, and fish remained in Illinois after the Pleistocene. Changes in climate and plant life at the end of the Ice Age were beneficial to some animals, and their populations expanded. Mammals such as coyote, beaver, and white-tailed deer were here during the late Ice Age and are still here today. They can all tolerate a variety of climate conditions and adapt to new or changing environments.

Migration: Many species left Illinois at the end of the Pleistocene. Some, such as the yellow-cheeked vole, moose, and muskox, moved north as the glaciers retreated. All three species prefer cooler climates, and the habitats and foods they needed for survival were now located farther north.

Extinction: Many species became extinct at the end of the Pleistocene. Changing conditions were too stressful, and they died out. Jefferson's ground sloth and the giant beaver disappeared about 13,500 years ago, mastodonts and mammoths by 13,000 years ago. Paleontologists, archaeologists, and geneticists have learned much about these animals, but they are unsure why they vanished from North America.