CINCINNATI -- The Cincinnati Zoo and Botanical Garden is famous for lots of things.
Depending on your perspective, this might make it more infamous than famous: The zoo has the world's largest bank for polar bear poop.
Researchers collect the droppings from every polar bear in captivity across North America because they want to understand bears' pregnancy.
Right now, if the zoo's female polar bear Anana gets pregnant, her caretakers might not know it until she gives birth. That's a problem as scientists race to save the species through a successful captive breeding program.
Dr. Erin Curry, with the zoo's Center for Conservation and Research of Endangered Wildlife, is not the first person who's tried to develop a pregnancy test for polar bears. Others have tried for years. It's tough.
But those others didn't have 40,000 fecal samples at their disposal. Cincinnati researchers have been collecting polar bear poop since 2008; they also have samples from otters, rhinos and red pandas. The poop bank is so big researchers keep dried-out samples in a bathroom closet.
"It's a full house," Curry said.
When Cincinnati's scientists get poop from other zoos, they inventory it, transfer it to tubes to take the moisture out, then weigh out a small amount. At this point, it looks like dirt or grass. Then they add ethanol to pull out the steroids or whatever they are trying to measure from the sample, and test for steroid metabolites.
From that, Curry says the team can learn about an animal's reproductive status and stress level. But they can't rely on hormones as the only indicator: Even non-pregnant female polar bears can show increases in progesterone, an indictor of pregnancy. That's called "pseudo-pregnancy," and other animals have them too.
The Cincinnati Zoo's research could end the uncertainty by using proteins instead.
"I'm hoping that this pregnancy test that we're working on will be applicable to those species as well, so hopefully it will be a pregnancy test for bears and cats and dogs and red pandas," Curry said.