How Zoo Knoxville Leads the Way in Hatching Herps

In Cover Stories by S. Heather Duncanleave a COMMENT

At Zoo Knoxville, inspiration for successfully hatching baby tortoises was found in an unlikely spot, although it’s the sort of place that has probably bred inspiration before: A wine cooler.

After trial and error, zoo experts developed a recipe for northern spider tortoise hatchlings that included incubating the eggs, then cooling them in the wine cooler, sometimes repeatedly and over many months, to mimic the seasonal weather changes that would occur in the species’ native Madagascar.

No zoo had ever managed to hatch the critically endangered northern spider tortoises in captivity, explains Michael Ogle, the zoo’s curator of reptiles, amphibians, and birds. In 2006, Zoo Knoxville became the first. It was also the first to hatch another Malagasy species, the flat-tailed tortoise, and was second to hatch two others from the same island.

Zoo Knoxville has allowed its animal curators great influence on the way the zoo contributes to scientific research. That can take the form of which species it displays and breeds, but also how it works with scientists to reintroduce species to the wild or gather more information on their habits and habitat. For example, although the zoo isn’t funding the work, it has given keeper Stephen Nelson time on work days to pursue research into a possible new mudpuppy species in the Hiwassee River. (On the way back, he solicitously stops to buy Monterey Mushrooms from the guard shack of the plant in Loudon, as a treat for the tortoises he left behind for the day.) Zoo Knoxville has also participated in a program releasing endangered bog turtles in Tennessee every year since 1991. Of 175, at least 75 have survived, Ogle says.

Almost by accident—but really by the sheer force of enthusiasm and determination of its reptile curators over the years—Zoo Knoxville has become a world leader in tortoise and turtle conservation and breeding.

No zoo board ever sat down and evaluated all the options and decided, “We’re going to make tortoises our specialty.” But it basically happened anyway as a result of the leadership of longtime herpetology director Bern Tryon and now Ogle. Ogle is the chair of the Chelonian (turtle and tortoise) Advisory Group for the Association of Zoos and Aquariums, which manages 48 turtle and tortoise breeding programs. Ogle says Zoo Knoxville now houses 28 tortoise species or subspecies, including 16 that have been identified as critically endangered and six considered endangered by the International Union for Conservation of Nature. The zoo hatches about 20 tortoises a year. In August, the zoo hatched several endangered black-breasted leaf turtles, a species native to Southeast Asia that had not bred successfully at Zoo Knoxville since 2009.

Many of the zoo’s contributions to reptile, amphibian and salamander research happen inside the aging reptile house an a nearby off-exhibit building dubbed “the kitchen.” The zoo’s five-year master plan includes a new reptile house, and (in the proud tradition of zoo workers shaping the collection) Nelson is hopeful it will have capacity to house more salamanders, many of which need tanks with moving water.

Currently, floor-to-ceiling incubators hum in the staff space behind the clouded reptile tanks. The sleek machines let the zoo choose the sex of the tortoise offspring. For many of these species, four degrees makes the difference between a male and a female.

Malagasy tortise eggs are often chilled between incubation periods to mimic seasonal temperature changes back home. The eggs are carefully labeled in pencil and nestled in plastic tubs.Tricia Bateman

Malagasy tortise eggs are often chilled between incubation periods to mimic seasonal temperature changes back home. The eggs are carefully labeled in pencil and nestled in plastic tubs.

The potential tortoise parents live in huge plastic tubs filled with wood chips or sand, with plastic pipes cut in half to make domed tunnels for shelter. The tubs are stacked on wooden racks. Heat lamps dangle by chains and cords above these compact habitats, water burbling loudly in the background.

Most people think of tortoises as slow, but the Burmese star tortoises are zipping around their tub on jagged, claw-tipped legs. The species was functionally extinct until being reintroduced in the wild a few years ago. Beneath them, fog seems to pour out through a tube and settle over the metal tub of plowshare tortoises, a Malagasy species found in only four other zoos. These particular tortoises were confiscated from smugglers in Hong Kong. Black and gold hexagons decorate their shells, which on males have a long lip called a “scoot,” used to flip rivals onto their backs. (“Mess with my girl, eh? Try to put the moves on her with your feet waving in the air.”)

The five Malagasy tortoise species at Zoo Knoxville are found in the wild only on the large island off the coast of Africa, where they are disappearing because smugglers trap them for the Asian pet trade, Ogle says. However, Ogle says natives on the southern part of the island are their allies, believing the tortoises could be ancestors. “It’s taboo for them to even look at a tortoise,” he says.

The Turtle Survival Alliance has twice sent Ogle to Madagascar to share his knowledge and help successfully reintroduce tortoises seized from poachers. When the alliance built a school for one of the native communities nearby, Zoo Knoxville donated and raised $3,500 to help buy desks, school supplies and soccer balls, say Ogle and Tina Rolen, zoo communications director. Rolen says the zoo has also raised $10,000 since 2009 to support the work of the Turtle Survival Alliance in Madagascar.

Later this month, Zoo Knoxville is helping pay for Nelson to visit one of the Madagascar tortoise reintroduction centers.

Ogle says his own trips to Madagascar yielded ideas that helped Zoo Knoxville tortoises. Seeing all the types of food tortoises were browsing on in Madagascar led him to expand the diet of the tortoises here, which he says has increased breeding success.

“Any time you see the animal where they really live, it just makes things click,” he says. “Seeing how they move and where they hide gives you ideas about how to replicate that.”

The zoo’s ability to breed these reptiles allows it to boost wild populations. Ogle says the zoo will soon be sending Roti Island snake-necked turtles for reintroduction to the wild.

It took many years for the zoo to achieve such successes. For example, it had owned and bred Malagasy flat-tailed tortoises since 1975, but it didn’t manage to hatch them until 2002.

That happened on Ogle’s day off. For fun, he and a friend were out looking for snakes at Great Smoky Mountains National Park when a supervisor from work called to ask, “Do you know what you did?”

“I thought I’d let a snake out or something,” Ogle recalls.

Instead, he was hatching an egg. (The process took a day and a half, so he didn’t miss it.)

Zoo Knoxville officials are hoping much more of this action will be visible to visitors when the zoo builds a new reptile house as part of its five-year master plan. For now, the 3-week old pancake tortoises, no bigger than golf balls, crawl enthusiastically on each other’s backs in a little plastic shoe box in “the kitchen.” Behind them, impressed tortoises have stacked themselves up like a Dr. Seuss illustration, mouths hanging open. “They’re heavy breathers,” says Ogle, only half joking. The zoo’s trial-and-error work in this cramped space is keeping a lot more rare tortoises breathing for years to come.

S. Heather Duncan has won numerous awards for her feature writing and coverage of the environment, government, education, business and local history during her 15-year reporting career. Originally from Western North Carolina, Heather has worked for Radio Free Europe, the Institute for War and Peace Reporting in London, and several daily newspapers. Heather spent almost a dozen years at The Telegraph in Macon, Ga., where she spent most of her time covering the environment or writing project-investigations that provoked changes such as new laws related to day care and the protection of environmentally-sensitive lands. You can reach Heather at

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