The responsibilities of a rabbit dog are pretty straightforward, and no one knows them better than Mason Lusk, who used to have the job himself.

When Lusk was growing up "poor as a snake" in West Virginia coal country, he often was called upon by his older brother to jump bunnies from their hiding spots, providing sport for out-of-town gunners.

"For some reason I could see them," he said. "I don't know why. I'm color blind. Maybe that had something to do with it. I could look into a thicket and see 'em sitting there. I'd say to the people, 'Can't you see that rabbit?' Then I'd kick the bush and out they'd come."

The folks for whom he performed this service had come to town to do business with Lusk's brother, who ran the coal company store. When the Lusks showed the visitors a good time -- 30 or 40 rabbits, for example -- it greased the wheels of commerce.

But Lusk said he would have done it just for the fun.

From these humble, Depression-era origins Lusk grew up to become a technical writer in Washington and a breeder and trainer of hunting dogs in his Secreferret kennels in Silver Spring.

His crowning achievement came after he retired six years ago, when Lusk bred the beagle that is this month's "cover dog" in Hounds and Hunting magazine, 1984 national gun dog champion Mickey's Gus.

After 50 years of fooling around with dogs, did that make him proud? You bet. "That hound has the best field performance of any hound alive, and he was bred right in my back yard," boasted Lusk, who made the mistake of selling Mickey's Gus as a pup, but kept one of the litter mates, a tiny, spunky, caramel-colored bitch named Secreferret Allie M.

It was to display the talents of Allie and another beagle called Secreferret Rock and Roll that Lusk invited me to a 500-acre dairy farm in Western Maryland on opening day of rabbit season Friday.

"I'll show you something I guarantee you've never seen before," he said as he drove through the rolling farmland along I-270: "A dog that retrieves rabbits. Now, you might think I'm blowing smoke, and these dogs might make a liar of me today, but that's what they do."

He turned off the highway, drove through a little town and followed a gravel driveway to a pasture dotted with woodpiles, greenbrier thickets, stone outcroppings and rusty, discarded farm equipment.

"I love this farm," said Lusk, who saw in the overgrown places recollections of the dirt farms he knew as a boy. The thickets and rocks provided rabbit cover and the pasture grass fed the bunnies, he said, cursing "clean, modern machine farming" as the cause of a decades-long decline in rabbit populations.

Lusk turned the hounds loose. "Come back here," he hollered as they lit out for the best rabbit cover on the farm. "I want to save that patch for the afternoon, when the rabbits run better," he said, "but the dogs don't want to wait. They know where the game is."

To watch good hunting dogs work is a pleasure, and these were good ones.

Allie jumped a cottontail in a huge thicket. You could hear her bawling, and then Roll joined in. Shortly the rabbit bounded out into the pasture with both dogs in hot pursuit. I shot at the rabbit as it zoomed by, but missed.

"You just set up by that fence and stay still," said Lusk. "They'll run him back to you, as long as he doesn't go in a hole."

It took a while, and the persistence of the dogs was remarkable. They lost the trail and found it again. They barked like mad, tracking, then fell silent as they sought the lost scent. They ran and stopped and ran some more. You could watch them from the hill, working in the high grass of an unmowed field, backtracking, splitting up, regrouping when they found something hot.

Fifteen minutes after they ran the rabbit out of the big thicket they ran it back. At the proper moment, Lusk swung his shotgun and tumbled the rabbit. Lusk never moved, and when Roll found the fallen game, she picked it up and delivered it to her master's hand, exactly as advertised.

Quite a sequence, and Roll and Allie repeated various parts of it a couple dozen times before the day was done. They jumped and ran so many bunnies that after we had enough for a nice Brunswick stew, Lusk stopped shooting and just enjoyed watching the races.

You'd think dogs like that would require elaborate training to do what they do, but Lusk insists it's all in the breeding.

"They're born to this," he said. "I can boil down all their training into one word: Exposure. As long as you expose them to rabbits, take them outdoors and show them what you want, it's in the blood."