TEMPERATURE REGULATION IN DESERT BIRDS AND MAMMALS 



Jack W. Hudson 



Birds and mammals living in deserts utilize a variety of physio- 

 logical, morphological, and behavioral patterns for coping with their 

 environments. Although any pattern is adaptive when it allows a spe- 

 cies to live and reproduce successfully in its habitat, there are ex- 

 amples of desert species which illustrate unique physiological mech- 

 anisms for coping with high temperatures and limited availability 

 of water. For example, the camel ( Camelus dromadarius ) shows 

 striking thermoregulatory adaptations to high temperatures and 

 limited water supplies (Schmidt-Nielsen et al., 1957) and the kang- 

 aroo rat ( Dipodomys merriami) demonstrates an excellent capacity 

 to conserve water (Schmidt- Nielsen et al., 1948a, 1948b). However, 

 some species of birds and mammals are able to occupy the desert 

 habitat even though they have no unique thermoregulatory capabilities 

 or special abilities to conserve water. For example, the wood rat 

 ( Neotoma lepida ) has no unique thermoregulatory ability, and it has 

 only a modest capacity to conserve water, acapacity approximately 

 equivalent to that of the Norway rat (Lee, 1960). Likewise, the House 

 Finch ( Carpodacus mexicanus ) and the Mourning Dove (Zenaidura 

 macrura), which may live in the desert, have no special ability to 

 minimize water requirements (Bartholomew and Cade, 1956; Barth- 

 olomew and MacMillen, 1960), while the Abert Towhee ( Pipilo aberti ) 

 does not possess any capacity for temperature regulation absent in 

 other passerines (Dawson, 1955). Furthermore, neither the House 

 Finch nor the Mourning Dove is able to process salt solutions as 

 concentrated as might be expected if its kidney were well adapted 

 for the conservation of water (Bartholomew and Cade, 1956, 1958, 

 1959; Bartholomew and MacMillen, 1960). 



There are many ways birds and mammals can avoid the environ- 



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