Apart from mammals, do other groups of animals maintain a high and constant body temperature?

 Apart from mammals, birds are the groups of animals that maintain a high and constant body temperature.

They are homoeothermic or warm-blooded animals like mammals. They are adapted to the aerial mode of living hence during the flight they need a constant supply of energy and oxygen. This is fulfilled by the double circulatory system and an efficient respiratory system aided by air sacs. Since they perform a high metabolic activity, they maintain a constant body temperature.