boundary rider

noun2

1. •
   (Australia) A person employed to travel along the boundary of a station, to check and maintain the fencing.

   • For these sixty-seven and a half miles of fence we must have three men known as boundary riders. A boundary rider is one whose duty is to see that the fence is in order. — 1892
2. •
   (Australia) A commentator on Australian rules football games who reports from the boundary of the field of play, and interviews players on the interchange bench as well as coaching and medical staff.