Energetics meets sexual conflict: the phenology of hibernation in Tasmanian echidnas (Tachyglossus aculeatus setosus)

1. Echidnas are egg-laying mammals found across Australia and in Tasmania they hibernate resulting in a most unusual mating system: males enter hibernation in late summer-early autumn and arouse in late autumn-early winter to mate, although females are still hibernating. Groups of males compete for matings and both males and females mate with multiple partners. Females that mate early return to hibernation even when pregnant, and males continue to mate with pregnant females. We asked to what extent to can the bizarre combination of behavioural and physiological features that characterize reproduction of Tasmanian echidnas be attributed to their phylogeny, and how much is a consequence of their ecology? 2. To understand the interaction between energetics and the echidna mating system in determining the timing of echidna hibernation we analysed data from an 18-year study of a wild population of Tasmanian echidnas 3. Males with high fat reserves arouse earliest and seek out suitable femal...