Animal detection systems

A detection tag for detecting of a reproductive status of animals, the detection tag comprising:

• a first surface configured to be fixed to a hide of an animal;
• a second and opposite surface including an abradable material;
• a first electronic signal transmitter configured to transmit a first electronic signal;
• a second electronic signal transmitter spaced apart from the first electronic signal transmitter and configured to transmit a second electronic signal, the first and second electronic signals having delectably different characteristics;
• and
• a signal shield shielding one of the first or second electronic signal transmitted by the first or second signal transmitters such that only the electronic signal from the other first or second electronic signal transmitters is transmitted from the detection tag;
• the detection tag being configured such that removal of some or all of the abradable material damages or removes the signal shield such that the electronic signal produced by said one of the first and second electronic signal transmitters is no longer shielded and the electronic signal from both the first and second electronic signal transmitters are transmitted from the tag.