Where Does All the Poop Go?

Fecal sample storage at Lincoln Park Zoo's Davee Center for Epidemiology and Endocrinology

Far from being a total waste, animal feces let zoo scientists, including Lab Associate Michael Landeche (below), learn more about animal stress and reproduction.

Storing Fecal Samples for Hormonal Analysis

Where does all the poop go? And how much is there?
—Christy Hruska, Zoo Visitor


Most of the poop produced by the zoo’s animals is hauled off by a certified waste management company. But plenty of it is repurposed.

How much? Try tens of thousands of fecal samples from more than 50 species. All of it stored in carefully labeled bags and boxes and stacked in freezers located throughout the zoo.

This dung depository provides vital material for the zoo’s Davee Center for Epidemiology and Endocrinology. Researchers led by Davee Center Director Rachel Santymire, Ph.D., extract hormones associated with stress and reproduction from the feces.

Measuring hormone levels over time can reveal patterns that help guide animal care and welfare decisions. Like when to introduce a breeding pair of rhinos—normally solitary animals—at just the right time. Or whether construction on the upcoming Regenstein Macaque Forest is stressful for the African wild dogs who live nearby.

“We have 10 freezers around the zoo—21-cubic-foot capacity like your standard home fridge—and they’re all full,” says Santymire. “We keep processed samples in test tubes and extra samples in case we have questions later about those animals and want to run tests again. The stuff we’re actively working on is stored in three freezers at the lab.”

Michael Landeche, lab associate at Lincoln Park Zoo's Davee Center for Epidemiology and Endocrinology

She summarizes her team’s workflow as such: “Animals defecate. Keepers put the feces in sealable bags, label it for us and throw it in the freezers. We come by monthly to pick up samples from the black rhinos, red river hogs, Bactrian camels, leaf-tailed geckos, La Plata three-banded armadillos…and process samples every month. We analyze about 10,000 samples a year, and we’ve been doing this for seven years.”

Do the math.

The freezers also store fecal samples collected and pre-processed by field researchers studying wild chimpanzees in Tanzania’s Gombe Stream National Park and mountain gorillas in Rwanda. The sample tally on those? About 3,600 for the chimps, 9,000 for the gorillas.

“Once we finish a study or publish our research, I ask myself, ‘Time to throw out these samples?’” says Santymire. “But I always have more questions—and the animals keep pooping. My strategy? Buy more freezers!”

By Craig Keller • Published January 28, 2014 • Originally published in Winter 2013 Lincoln Park Zoo magazine

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Lincoln Park Zoo magazine Winter 2013 issue

Zoo FAQs
How does the zoo stay free? How are the animals paired up? Do the animals get bored? Where does all the poop go? We answer your most frequently asked questions in the latest issue of Lincoln Park Zoo magazine.