He's trapped four foxes and two wild dogs, one with a brindle coat, the other ''the ugliest dog I've ever seen''.

It's not a sudden explosion of dirt and painful crunch of cold steel on his fingers Mr Davis fears most when setting his traps. It's the worry of amateurs trying to copy him.

If they're lucky they might catch a dumb dog, but will make smarter ones more cunning.

A black wild dog leading a pack of others on killing sprees some years ago near Canberra eluded him while the other dogs were caught night after night by Mr Davis, a NSW Livestock Health and Pest Authority ranger.

''He'd go into the mountains and come back with more of his mates. They'd be caught too, but he was smarter. Myself and another trapper had to kill 40 dogs before we got him and the killing stopped.''

Tidbinbilla grazier Michael Shanahan lost 250 lambs - about $25,000 worth in one mob - last year.

He said dogs often killed for sport. ''We notice it, predominantly maimed sheep, bitten with half a leg missing, guts coming out, lots of badly bitten sheep. Lambing is the worst time because we just don't know we are losing lambs because the dogs take the lambs.''

Mr Davis said dingoes crossed with other breeds attacked sheep around their rears and some took out a kidney with a single bite.

He follows his own dogs along slushy tracks, creek lines and ridges, watching where they cock their legs to mark a stump or rock or tussock, and changes tactics until foxes and dingoes begin appearing in some of the 60 traps he's set across a wide stretch of rugged mountain ranges and edges of grazing land.

The rubber-rimmed traps are chained to a log which allows a trapped animal to move into cover until Mr Davis arrives and shoots them.

''They don't like looking at you, they avoid making eye contact. They cower, they know they're in a bad place. Some will stand and become very aggressive.''

Mr Davis has 24 years' experience and learned his craft from older trappers. He said anyone who claimed to have wild dogs figured out was simply revealing ignorance. He howls up wild dogs.

One evening on dusk he howled down a valley and was surprised at the huge response. ''You'd swear the whole valley was alive with them.''

ACT Parks and Conservation rural manager Brett McNamara said a ''nil tenure'' policy of allowing government land managers to work across various park and state boundaries had reduced attacks near Namadgi National Park over a decade. Syringe baiting which were injected into dogs, shooting and trapping were used.

But farmers object to government agencies preserving the majority of dogs as a top order predator for kangaroo and rabbit control. They want more trappers.

Mr Davis avoids the politics of feral animal management, which last month attracted $72 million worth of Commonwealth research funding.

It's the wily dingoes that fascinate and challenge him.

''You can hunt a dog for months. It'll do your head in.''