Field metabolic rate refers to a measurement of the metabolic rate of a free-living animal

Wildlife

Wildlife includes all non-domesticated plants, animals and other organisms. Domesticating wild plant and animal species for human benefit has occurred many times all over the planet, and has a major impact on the environment, both positive and negative....

 in the wild.

Method

Measurement of the Field metabolic rate is made using the doubly labeled water method, although alternative techniques, such as monitoring heart rate

Heart rate

Heart rate is the number of heartbeats per unit of time, typically expressed as beats per minute . Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep....

s, can also be used. The advantages and disadvantages of the alternative approaches have been reviewed by Butler, et.al. Several summary reviews have been published.