Cutaneous Water Loss in Small Birds

In recent years evaporative water loss (EWL) in birds has undergone extensive study.Although some investigators have assumed that because of the lack of sweat glands, all evaporation occurs in the respiratory tract, others have recognized the potential importance of avian skin as a site for evaporation.To date significant cutaneous evaporation has been reported in pigeons, Columba Zivia (Smith 1969; Smith and Suthers 1969), and Painted Quail, ExcaZfucto~ia chinen& (Bernstein 1969, 1970, 1971).This report provides data on both cutaneous and respiratory evaporation in four species of small birds native to mesic and xeric habitats.The results indicate that evaporation from the skin in all four species at thermoneutrality constitutes a major proportion of total EWL.Hence, with the documentation of cutaneous EWL in rodents (Tennent 1945; Chew 1955; Stupfel and Geloso 1959) and in reptiles (Chew and Dammann 1960; Bentley and Schmidt-Nielsen 19866; Dawson et al. 1966; and others), it can now be stated that the skin represents a major pathway for water loss in non-sweating representatives of all three classes d terrestrial vertebrates.