Water Flux in Chukar Partridges (Alectoris chukar) and a Comparison with Other Birds

Abstract

Total body water volumes and water fluxes were estimated in five chukar partridges (Alectoris chukar), using tritiated water. The birds were captured from a Negev desert population and were individually caged in an environment controlled room (Ta = 27 ± 1 C; relative humidity [RH] = 42% ± 2%). Daily water flux averaged 70.7 ml/kg body mass when the birds had drinking water and a dry ration ad lib. and was 22% higher when the birds were offered additional green vegetation. On the basis of data collected in a comparable manner, i.e., from nonstressed, captive birds offered food and water ad lib., an allometric equation relating water flux to body mass was calculated for avian species as follows: log water flux (ml/day) = 0.596 log body mass (g) + log 1.223. The chukar partridges and several other xeric zone birds had relatively low water fluxes when compared with mesic birds. We suggest that a standard experimental protocol be adopted for water-balance studies in birds to allow meaningful interspecific comparisons of water-related physiological functions.