Red colobus monkeys, native to East Africa, are extremely rare, so travelers going on a Kenya and Tanzania safari should familiarize themselves with the monkeys so they know what to look out for. Most prominently, colobus moneys do not have thumbs like other monkeys, explaining how they got their name which comes from the Greek word for "mutilated." These primates tend to stick to the trees and travel in groups of five to 10, so if you're lucky enough to spot one overhead, watch for more.