A Seasonal Study of Body Condition and Water Turnover in a Free-Living Population of Platypuses, Ornithorhynchus Anatinus (Monotremata).

Abstract

Body condition was assessed in a population of free-living platypuses (Ornithorhynchus anatinus) in the Upper Shoalhaven River in summer (February) and winter (September). Total body fat was estimated by measurement of tritiated water space and tail volume was also measured. Carcass analysis of dead platypuses verified a negative correlation between percentage body fat and percentage body water. The major store of body fat is located in the tail. In the live polulation, adult platypuses showed little seasonal change in body fat. Juveniles are relatively fat in February (soon after their emergence from their burrows) but at the end of their first winter they have lost a considerable amount of body fat. Juvenile males seem to possess negligible body fat stores in September. Changes in relative tail volume showed similar changes to those of estimated body fat. Some platypuses were recaught, and for these water turnover was calculated to be very high, at about 480 ml daily.