Identify a characteristic of mammals.
One characteristic of mammals is that they are warm-blooded, meaning they are able to regulate their body temperature internally in order to maintain a constant temperature, regardless of the temperature of their environment.
Complete the following task based on the instruction and optional input provided.### Instruction:
Identify a characteristic of mammals.

### Output:
One characteristic of mammals is that they are warm-blooded, meaning they are able to regulate their body temperature internally in order to maintain a constant temperature, regardless of the temperature of their environment.