Are all birds and mammals endothermic?

Yes, all birds and mammals are endothermic, meaning they can generate their own body heat to maintain a constant internal body temperature regardless of the external environment. Endothermy is a characteristic feature of these two classes of animals, distinguishing them from ectothermic animals (such as reptiles and amphibians), which rely on external heat sources to regulate their body temperature.

Birds:

All bird species are endothermic. They have a high metabolic rate, efficient circulatory and respiratory systems, and specialized adaptations to conserve heat, such as feathers and a high density of blood vessels in their extremities. Birds' endothermy allows them to maintain high activity levels, including flight, and survive in diverse climates, from the tropics to polar regions.

Mammals:

All mammal species, including humans, are endothermic. Mammals possess several physiological mechanisms for generating and regulating body heat, including a high metabolic rate, insulation provided by fur, and the ability to control blood flow and sweating. Endothermy enables mammals to remain active in various habitats, from hot deserts to cold arctic environments, and to maintain stable body temperatures necessary for their physiological processes.