Figure 2. External temperature logger record from female echidna 0118.

She entered hibernation in March, and her final arousal was on July 27 (arrow 2), when temperature variability increased. The subsequent reduction in variability (arrow 3) is associated with entry into the nursery burrow and egg-laying. Periodic arousals can be seen between April and July. In mid-July she shows an extended arousal (July 10–21), and we presume fertilization occurred at the time indicated by arrow 1.