Mammals are air-breathing vertebrate animals characterized by the possession of warm blood, hair, three middle ear bones, and mammary glands functional in mothers with young. Most mammals also possess sweat glands and specialized teeth. Mammals also include some of the largest and most intelligent creatures on the planet, including humans, and whales.

Mammals play many important roles for humans, including food sources (livestock), labor (plowing fields, riding horses), and industrial uses, such as the manufacture of glues and many important chemicals. Mammals are also some of the most cherished pets, including cats, dogs, hamsters and guinea pigs. They are even used to assist humans with daily activities, such as seeing-eye dogs and police dogs and horses. They also play valuable (if not immoral/debatable) roles in the medical and scientific industry as test subjects.

Connecticut has at least 60+ species of mammals recorded in the state. More common mammals include Eastern grey squirrels, chipmunks, groundhogs, white-tailed deer, opossums, and skunks. Less common and rare mammals include black bears (depending on where you live in the state), bobcats, flying squirrels, porcupines, coyote, gray wolves, and even moose. There have even been recent sightings of mountain lions.