DULUTH, Minn. — Dave Thompson can use some of the most unlikely objects — a discarded mirror, an empty Mountain Dew bottle, an odd-shaped piece of PVC tubing — in his work.

“When I go to Menards, it’s a lot different from normal people,” Thompson said.

Thompson is a zookeeper at the Lake Superior Zoo who specializes in primates. He uses donated materials and a few odd purchases to provide the Angolan colobus, red ruffed lemurs, callimico and cotton-top tamarins with new experiences and challenges daily.

He recently propped up a mirror donated by one of the zoo’s interns among the tamarins — tiny, high-energy monkeys from northwestern Colombia. The little creatures peered at their own images with fascination. Meanwhile, the bigger, more deliberate colobus investigated the puzzles Thompson had left them — including an upside-down, partially closed bottle and a cross-shaped PVC tube, both with treats inside.

At Zoo Central, meanwhile, zookeeper Jessica Jasek was working with the parrots, hanging homemade toys made partially from egg cartons inside the cages. A blue-and-gold macaw named Sam was making quick work of the cardboard portion of his toy.

It’s all good fun — and serious business. Zoo professionals refer to the daily efforts to stimulate their animals’ senses as enrichment, and it’s one of the things the Lake Superior Zoo must show it’s doing to regain the American Association of Zoos and Aquariums accreditation it lost in 2006.

Beyond that, enrichment makes the zoo a healthier, happier place for the animals, staff and visitors alike, said Leslie Larsen, the zoo’s director.

“Enrichment is part of animal care now,” said Larsen, who has been in the industry for 20 years, at the Lake Superior Zoo for 14 years and the zoo’s director for just over a year. “It’s every bit as important as giving them their food and water and their clean habitat. This is all the physical and mental stimulation that keeps these animals healthy in captivity.”

Thompson ticks off the senses that need to be stimulated: taste, sight, smell, touch, sound. Some of the senses are more important with some animals than with others. Smell isn’t significant for parrots, so Jasek concentrates more on sight, touch and sound. But it’s extremely important to the big cats, so when the sheep or llamas are done with their straw, it’s hidden in the big cats’ area.

“Then they get to smell that and play with that,” Larsen said. “They get pretty excited and then they realize the prey animal’s not there. Then they’re, like: ‘Oh, you didn’t bring us the real thing.’ ”

Animals also can be stimulated by perfumes and colognes. A recent story in the Wall Street Journal told of a study done by the Bronx Zoo that concluded that zoo’s cheetahs spent the most time with Calvin Klein’s Obsession for Men — 11.1 minutes — and the least with Estee Lauder’s Beautiful — 2 seconds.

Although the Lake Superior Zoo hasn’t broken it down to that extent, zookeepers have used perfumes, as well as catnip, spices and herbs for such animals as the big cats, wolves and reptiles, Larsen said.

The focus on enrichment even affects decisions about which animals to include in the zoo in the first place.

“Elephants shouldn’t live alone in captivity,” Larsen said. “They’re social animals. We had an elephant many, many years ago. A lot of people remember Bessie the elephant, and she had a great life here. But this zoo isn’t equipped to house a group of elephants. So we made a decision not to do that.”

Animals that are having their senses stimulated won’t exhibit what’s known as stereotypical behavior, such as pacing in a repeated pattern, Larsen said. That kind of pattern not only reveals distressed animals, it’s a turnoff for visitors.

“They don’t want to see stereotypical behavior,” she said. “They may not know what that word is. It doesn’t matter. It’s disturbing, because if you saw a person doing that you’d know that they weren’t in the best state of health. So of course we want our animals to feel good and feel like they’re in a safe and comforting and healthy environment. And we want visitors to know that about our animals as well.”