Water Turnover in Roadrunners under Different Environmental Conditions
1970; Oxford University Press; Volume: 87; Issue: 4 Linguagem: Inglês
10.2307/4083712
ISSN1938-4254
AutoresRobert D. Ohmart, T. E. Chapman,
Tópico(s)Animal Nutrition and Physiology
ResumoT•ts study reports on the use of tritiated water (HTO) to determine total body water and the kinetics of the water pool in captive Roadrunners (Geococcyx californianus).The Roadrunner is an interesting subject for the study of water turnover, as it occurs in the most arid regions of North America (Grinnell, 1907), consumes primarily animal material (Bryant, 1916), will drink water in the field (Sutton, 1940), but apparently does not require it (Miller and Stebbins, 1964; Ohmart, field observ.).In addition, data on its water losses and requirements are available (Calder and Schmidt-Nielsen, 1967;Calder and Bentley, 1967; Calder, 1968a Calder, , 1968b).To our knowledge, this is the first reported attempt to use the HTO (tritiated water) technique to determine body water loss in nondomesticated or desert dwelling birds under two different environmental conditions. METItODSThree wild-trapped adult and three hand-reared immature Roadrunners obtained near Tucson, Arizona during July 1968 were taken to Davis, California in September 1968 and housed together in a large outdoor cage.Body water turnover was studied under two sets of conditions.In the first experiment, rates of water turnover were determined by following the loss of tritium activity administered intravenously on 10 January 1969.Blood samples were then taken on alternate days through 22 January 1969.The test birds were housed together in an outdoor cage measuring 3 X 3 X 2.3 m.During the first test period, a total of 18.69 cm of precipitation was recorded and the maximal and minimal temperatures ranged from 16 ø to -4øC with a mean of the daily maxima and minima being 8øC.Water vapor pressure during the 13-day test ranged from 5.5 to 3.4 mm Hg with a mean of 4.45 at 8øC, which equals 55 per cent relative humidity.In the second water kinetics experiment, the birds were housed together in a climati-
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