Mammals have fur, a backbone, and are warm-blooded (regulate their own body temperature) ¹. Most female mammals produce milk and give birth to live young (as opposed to eggs). Common large mammals in Massachusetts include white-tailed deer, coyote, and black bears.  21% of the world's 5400 mammal species are threatened or recently extinct, according to the International Union for Conservation of Nature (IUCN). Primates are especially threatened ¹.