A seasonal change in blood cell volume of the Rottnest Island Quokka, Setonix brachyurus

Abstract

Comparison of the red cell and plasma volumes (T‐1824) of wild Quokkas captured in spring (October) with volumes of animals captured in autumn (May) showed that no seasonal change in average plasma volume occurred but a 42% average decrease in red cell volume did occur in autumn. Control animals kept in compounds showed no seasonal change in either average plasma or red cell volume. The available evidence suggests that the seasonal decline in red cell volume results from the semi‐starvation suffered by the wild population during the late summer and autumn of each year. The average relative red cell, plasma and whole blood volumes of well‐fed Quokkas captured in October were 24.6±3.1; 37.0±3.0; and 61.7±4.5 ml/kg, and equivalent measures of domesticated Quokkas were 28.0±3.2; 40.5±2.8; and 68.5±5.3 ml/kg. These values lie within the ranges of comparaable blood compartment volumes of eutherian mammal species.