COOBER PEDY, Australia — For anyone driving through South Australia’s outback, it does not take long to see why patrol officers like Alan Walton are needed to keep the country’s 3,500-mile-long dingo fence in order.

Early into a recent workday, Mr. Walton watched as a kangaroo — perhaps driven by the potential for greener pastures or a mate on the other side — slammed full-throttle into the fence, bouncing off like a boxer hitting the ropes.

Within minutes, Mr. Walton, 54, crawled his pickup truck, known locally as a ute, past the battered section of the fence. This time, the barrier was not breached. Other times, Mr. Walton has had to patch holes in the wire, stabilize a post or untangle an offending kangaroo.