Train, a 12-year-old Chesapeake Bay retriever from St. Louis, has been at the center of a wildlife conservation research team for about a decade, but he’s more focused on something else: his tennis ball.

Train is a conservation detection dog, one of the more unusual research tools for tracking elusive animals in the wild, and works alongside Washington University biology researcher Karen DeMatteo. The two have spent years on projects aimed at tracking carnivores in a biologically important stretch of Argentina and monitoring U.S. mountain lions.

Train’s work uses something most dogs do naturally: sniffing out poop. He has been trained to sniff out the droppings, known as scat, from specific species like jaguars, pumas, ocelots and other carnivores. Every time he finds the right sample in the field, DeMatteo gives the dog his prize — a tennis ball.

This high-level game of fetch makes a difference. The data the team collects helped create a “conservation corridor” in the Misiones region of Argentina. The corridor aims to connect pockets of protected land so that at-risk animals like jaguars can safely move across the region.

It took a while, though, to discover that a life of science was Train’s true calling. He was first trained as a narcotics dog for the Seattle police.

“He failed out of narcotics dog school,” said DeMatteo. “We say he was too energetic. Put him in an enclosed space, and he would bounce off the walls, his tail would be knocking things all over the place.”

But that energy is perfect for conservation work, where dogs often have to walk dozens of miles through the forest, DeMatteo said.

“He’s unstoppable in the field,” she said.

DeMatteo came to her research through an animal many people have never heard of — the bush dog, a canine that looks a bit like a bear the size of a cat. She studied the small animal for her Ph.D. research through St. Louis University and the St. Louis Zoo.

Bush dogs are famously hard to find in the wild and often elude wildlife cameras, so DeMatteo aided studies that attempted to lure them with smells, sounds and urine.

In 2007, she launched the research project that continues to this day in Misiones, Argentina, tracking the movements of bush dogs, jaguars, pumas, ocelots, and oncillas (a small spotted cat).

Train quickly became a star science dog.

A day in the field is hard work. They wake up before the sun rises and walk through the forest at least 10 miles every day, sometimes running into armed poachers and tough terrain on their way.

Train wears a bright orange harness, a little bell around his neck and booties to protect his paws. He can detect scat that’s buried in a hole or log and can pick up scents from droppings that are weeks or months old.

After each trip, DeMatteo brings scat back to the U.S. and performs genetic tests that allow her to confirm which species Train found and track their movements in Misiones. “I had proper permits for everything, but I would ask the gate agents: Do you want me to open them?” DeMatteo said. “They’d say: ‘It’s poop, right? Uh, no, please don’t.’ ”