RESPONSES AND ADAPTATIONS OF WILD BIRDS 

 TO ENVIRONMENTAL TEMPERATURE 



George C. West 



Birds maintain relatively constant bcxiy temperatur^Sv in gen- 

 eral several decrees higher than those of mammals, in spite of 

 external temperatures that range for some species to above 40 C 

 and for others as low as -60 G. The ability to maintain a constant 

 temperature in the face of such thermal extremes is dependent 

 upon the proper coordination and regulation of the mechanisms for 

 heat production and heat loss. A complete understanding of these 

 mechanisms would enable one to obtain a more thorough picture of 

 how birds adapt to their ever changing environments in nature. 



The basic principles of thermal exchange inhomeothermshave " 

 been well reviewed by Hart (1957) and more recently by King and 

 Farner (1961), who have shown that birds behave essentially as 

 heat machines, varying heat gain and heat loss to maintain a con- 

 stant temperature under all thermal conditions in which they are 

 capable of surviving. 



This review will attempt to summarize some of the recent work 

 on the responses of wild birds to temperature, with particular em- 

 phasis on the effect of environmental temperature below body tem- 

 perature and the bioenergetic adaptations of birds to temperature 

 under natural conditions. 



Body Temperature 



A large number of deep body temperatures have been recorded 

 for adult birds in almost every order (Baldwin and Kendeigh, 1932; 

 Bartholomew and Dawson, 1954; Bartholomew and Gade, 19 57; Daw- 

 son, 1954; Earner, 1956; Farner etal., 19 56; Irving and Krog, 1954, 



♦Contribution, in part, from the Division of Applied Biology, National Research! 

 Council, Ottawa, Canada. Issued as N.R.C. No. 6629. 



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