a device to detect parturition of a pregnant livestock or zoological animal which may be inserted into the birth canal of the pregnant animal comprises a transparent housing having an internal cavity adapted to hold therein a photo - detecting element which is dormant while in the dark birth canal . when the housing is expelled from the birth canal by a fetus pushing it out at parturition , the brighter environment activates the photo - detector which drives associated circuitry which activates an integral tone generator to cause it to emit a pulsed , high frequency tone . a remotely located receive identifies the tone from the ejected device and activates any one of known , ultimate alerting devices , such as a radio paging system , for example .