Automatic detection of parturition in pregnant ewes using a three-axis accelerometer

•An on-animal sensing system is proposed to automatically detect parturition in pregnant ewes.•The proposed method constructs a metric of ewe activity and computes changes in activity distributions over time.•Parturition is estimated from the time period with the most significant change in ewe activity.•The proposed method detects the onset of parturition with a mean absolute error of 5.33 h.•The proposed method correctly detects the birth date of 84% of lambs.