Simplify the following text for a Grade 7 native English-speaking person.
Original: The reindeer ( Rangifer tarandus ) , also known as the caribou in North America , is a deer from the Arctic and Subarctic , including both resident and migratory populations .
Simplified: The reindeer ( Rangifer tarandus ) is an even-toed ungulate mammal of the deer family . In North America it is also called caribou .