Apparatus for managing animals such as but not limited to livestock. In some embodiments, an ear tag assembly has a tag, a backing member and an elongated shaft assembly configured to pierce and extend through an outer ear (auricle) of the animal. A first temperature sensor is disposed within the shaft assembly to obtain an ear temperature measurement of the animal. A second temperature sensor obtains an ambient temperature measurement adjacent the animal. A control circuit accumulates temperature data from the first and second temperature sensors in a tag memory for subsequent transfer, via a wireless communication network, to a data collection unit. Additional sensors may be utilized. In some cases, the backing member may house a battery to power the control circuit. The backing member may be removably attachable to the shaft to allow replacement of the battery.
