warmblooded

Warm-blooded is a common, informal term used to describe animals that maintain a relatively constant body temperature largely by internal heat production. The term is most often applied to birds and mammals, which regulate heat through metabolism, insulation, and controlled heat exchange with the environment. Some organisms that do not fit neatly into this dichotomy may exhibit partial or behavioral thermoregulation.

Mechanisms include endothermy, which produces heat via metabolic processes; insulation that reduces heat loss; vasomotor control that adjusts heat distribution; and evaporative cooling strategies such as sweating or panting. Birds and mammals also rely on behavioral strategies (sunning, seeking shade, burrowing) to complement physiological control.

Implications of warm-blooded physiology include the ability to maintain activity across a wide range of ambient temperatures, broader geographic ranges, and independence from environmental conditions for sustained performance. These advantages come with higher energy requirements and a greater reliance on a regular food supply.

Evolution and terminology: Endothermy evolved independently in the lineages leading to birds and to mammals. The label warm-blooded is imprecise and can be misleading, as some species outside birds and mammals regulate body temperature to a degree, and some birds and mammals can tolerate large fluctuations or enter torpor. In scientific literature, endothermy and homeothermy are preferred terms for describing mechanisms and constancy of temperature, while warm-blooded remains a popular, non-technical descriptor.