The hero search dog of Northern California doesn’t even get a dog biscuit when he finds somebody.

“He likes chasing balls,” said the dog’s owner, Rich Cassens. “That’s his reward. I throw him a ball. No biscuit required.’’

The dog is a 3-year-old golden retriever named Groot, and all Groot did on Saturday was help Cassens locate two lost hikers from Palo Alto who had been stranded in a ditch of brush, thorny blackberry and poison oak near Inverness for more than a week. Cassens and Groot were among scores of volunteer searchers who had bushwhacked for days, looking for the elderly couple.

Now life is returning to normal, and Cassens is determined not to let fame swell Groot’s soft, fuzzy head. This week it was back to work for man’s best friend, along with man. The two of them were spending a pleasant afternoon playing their favorite game of find-the-dead-body near their home in Grass Valley.

The game involves Cassens hiding little mesh pouches and letting Groot try to sniff them out.

Do not ask about the contents of the little mesh bag, Cassens said. Inside are “human remains,” essential for teaching a search dog what a dead human smells like. Could be just about anything corpse-related — teeth, hair, tissue, bone. If you sign a form that says you wouldn’t mind being a whole-body donor when you die, some of you might wind up in the little mesh bag to keep Groot and his fellow search dogs on their toes, all 20 of them.

“Woof,” said Groot.

Cassens hid three of the mesh bags in a church parking lot. Then he let Groot out of the back of the car and put his “search dog” vest on him. The vest is mostly for show, for whenever Groot is getting his picture taken. That’s because Groot already knows who he is and because, when it’s time to get down to business, the vest has a way of getting caught on things like blackberry thorns.

“Find Waldo!” hollered Cassens, which is his way of telling Groot that it’s time to put his nose to work.

Groot raced around the lot as if searching for parking space at Costco on Christmas Eve. Within seconds, the noble dog had found the first of three pouches, in a ditch. It took longer to find the second one, which was hanging from a tree branch, and the third one, which had been shoved into a storm drain. The hero dog was distracted by a brown horse on the other side of the parking lot fence, who moseyed over to see what his fellow mammals were up to.

“Groot!” hollered Cassens. “Find Waldo! It’s your big moment!”

After about 10 minutes, Groot nosed out the other two mesh pouches and got his plastic ball.

Cassens said a real search and a pretend search are much the same to Groot. The smell is similar and so is the ball he gets to chase afterward.

On Saturday at Point Reyes, Groot had been taking part in his very first official search as a newly certified member of the California Rescue Dog Association. Groot, Cassens and another searcher had been assigned to search an overgrown gully near Inverness, about three miles from where hikers Carol Koparsky and Ian Irwin were last seen eight days earlier. It was a low-priority area, meaning that nobody in charge expected them to find anything there.

They fought their way through mud, foliage, vines, fallen trees and poison oak — lots of poison oak. After a couple of hours, Cassens heard voices and sent Groot on ahead to investigate. Groot sniffed out the couple, who had been living for a week on ferns washed down with water from a puddle.

The couple was helicoptered to safety and treated for exposure. They’re doing fine and have requested privacy. Groot and Cassens went home to Grass Valley, without benefit of helicopter.

Cassens, a $50-an-hour dog trainer by profession, said he and Groot do their searching on a volunteer basis. On his arm, Cassens bears a tattoo of the search association’s motto — “So that others may live.” Groot gazed at it with big eyes, or maybe he was looking at the ball in Cassens’ right hand.

The two have been a team ever since Cassens picked Groot out as a 6-week-old puppy from among nine littermates at a breeder’s kennel in Redding. On that fateful day, Groot scampered after a ball that Cassens threw, which demonstrated initiative, and did not flinch from a loud noise, which demonstrated focus. The match was made.

Searching, Cassens said, is actually fun — except for the poison oak.

“I get to be out in the woods with my dog, goofing off,” said Cassens. “Well, maybe not goofing off. That’s not the right thing to call it. But I do get to be out in the woods with my dog.”

Steve Rubenstein is a San Francisco Chronicle staff writer. Email: srubenstein@sfchronicle.com Twitter: @SteveRubeSF