Mammals can also generate little bursts of heat by shivering, and shivering causes muscle contractions to warm the body. Given these facts, mammals can also generate little bursts of heat by among the following options:
- muscle contractions
 - circulation
 - exhalation
 - Temperature changing
 - Movement of an air mass
 - flow of electrons
 - vibrations
 - with their fur


 

 muscle contractions        