The tail-mounted MooCall Calving-Alert Sensor predicts when the cow will most likely give birth by monitoring her tail movement patterns. When those movements reach a certain level of intensity, the device sends a SMS text alert to up to two different mobile phones about an hour prior to calving. The MooCall package includes: the sensor; the software; 12 months of data, updates, and support; and a battery-recharging power cord. One sensor should be sufficient for a 40-cow herd that experiences 6-7 calvings a week.