Animals that have a constant body temperature are called homeotherms, or warm-blooded animals:
Homeotherms
These animals maintain a constant internal body temperature, usually within a narrow range of temperatures. They have a built-in thermostat that allows them to maintain a stable internal body temperature regardless of external influence.
Endotherms
Another term for homeotherms, these animals are warm-blooded and maintain a constant body temperature independent of the environment. Birds and mammals are examples of endotherms.
