For the past two years, polar bear poop left around the Assiniboine Park Zoo, in Winnipeg, has been sparkly. That's because zookeepers have been mashing up glitter into the bears' diet of ground-up horsemeat, according to a recent CBC report. Different bears eat different colours of glitter: that way, scientists can tell whose poop is whose.
It sounds bizarre, but the Assiniboine Park Zoo isn't the only place where glittery poop is important for scientific research. Scientists have used this technique for years.
"A lot of information can be found in poop," Brandie Smith, associate director for animal care scientists at the Smithsonian's National Zoo in Washington, told Motherboard. Fecal samples are a way to track the animal's reproductive cycles, whether it's stressed out, and its general health, she continued. Examining poop is non-invasive, and doesn't bother the animal.
"You can find a lot of information in the urine [too], but it's ephemeral," she added, meaning it quickly disappears into the ground. Elephants can be trained to pee into a cup, according to Smith, "but to do that for all animals is a lot of work."
When several animals live in one enclosure—like gorillas, cheetahs, or polar bears—it can be hard to tell everybody's poop apart. "One option is to watch them poop and collect it immediately," but that obviously has its challenges. The idea here is to put a marker in their food that they won't digest, and that's easy to spot once it passes through the other end. "What goes in is what comes out," Smith said. "We use glitter."
Regular, craft-store glitter, in colours like red, blue, green and gold. It's harmless to the animals, she said.
At the Smithsonian Zoo, this technique has been used on lots of different animals, including red pandas and cheetahs. In the case of Dorothy, an elderly Cuban crocodile, it's been especially useful. Cuban crocs are critically endangered in the wild, Smith said.
"The more you can make, the better," she said, referring to captive breeding programs. Zookeepers have been closely monitoring Dorothy's feces to figure out her reproductive cycles, and watching for when she lays eggs. (Dorothy, who is 58, shares her enclosure with two other crocs, named Blanche and Jefe.)
Poop science in the zoo has helped biologists better understand animals in the wild. There, "it's really hard to get your hands on an animal," Smith said. "You could be in a bamboo forest in China for a week, and never see a panda. But you'll see a lot of poop." Those samples could be enough to determine the animal's approximate age and health status, important information when assessing the population.
"The information we can collect on wildlife populations has developed exponentially from the poop techniques developed in zoos," she said.
As for what would happen if a human ate some sparkles, well—doctors have recommended against downing glitter recreationally, possibly because it can be abrasive and hasn't been approved for human consumption, and that seems like sound advice. Still, there's no reason it wouldn't leave a dusting of sparkles in the toilet bowl. As Smith said, speaking of the animals she works with: "What goes in is what comes out."