Many mammals make use of burrows but only a few birds do -e.g. The evolutionary reason is that, being unable to feed on insects and nectar in the darkness, the hummingbird would lose too much energy overnight. Respiratory evaporative heat loss - this is the most important form of heat loss in birds and virtually all birds exhibit some form of panting. The hyoid bone flexes and the whole area is suffused with blood. Wings can be held away from the body and the feathers elevated.
Albatrosses raise their feet off the ground and spread their wings to shade their feet.
The Herring Gull orients the white part of the body towards the sun to reflect heat. The Wood Stork, when hot, directs its liquid excrement onto its long legs. The domestic chicken splashes water over its comb and wattles. The Egyptian Plover wets its belly in puddles and cools itself and its eggs and the sand around the nest. Precocial species are those hatched covered with down and are able to respond immediately to changes in the ambient temperature as they are capable of thermoregulation or are able to withstand body temperature fluctuations without harm.