Seasonal-Variation in Water Flux, Field Metabolic-Rate and Food-Consumption of Free-Ranging Koalas (Phascolarctos-Cinereus)

Abstract

Mass-corrected field metabolic rates of free-ranging male koalas in central Queensland, Australia, varied between 0.329 MJ kg0.75 day-1 in summer and 0.382 MJ kg0.75 day-1 in winter. Field water influx measured 50.8 mL kg-0.8 day-1 in winter, increasing to 59.9 mL kg0.8 day-1 in summer for the same koalas, and was positively correlated with values for leaf moisture of food. Winter rates of water influx for koalas from Springsure were lower than those recorded for koalas from Victoria for the same period of the year. Mass-corrected feeding rates were lower in summer than winter; wet food intake was significantly lower than reported for similar sized female koalas from Victoria. The preferred browse was Eucalyptus crebra in winter and E. tereticornis in summer. Our study indicates that in central Queensland seasonal changes in diet selection by male koalas reflect increased energy requirements in winter and increased water requirements in summer.