Polar bears across North America are pooping out flashy, glittery piles of poo for the sake of science.
Housed at the Lindner Center for Conservation and Research of Endangered Wildlife at the Cincinnati Zoo (CREW), the Frozen Fecal Bank stores 30,000 polar bear stool samples collected from 63 polar bears at 30 North American zoos. Don’t worry, it’s all in the name of science. Caretakers feed polar bears markers – something that passes through their digestive tract intact – so that they can distinguish the fecal sample of one bear from another.
“For example, if a male and a female bear are housed together but we only need fecal samples from the female to monitor her reproductive hormones, a zoo may feed a little bit of glitter or icing coloring so that they can more easily identify her fecal sample and not accidentally pick up a sample from the male, which would confound our results,” explained the zoo's lead polar bear expert Erin Curry. After, animal care staff can then collect the correct sample, throw it in a baggie, and ship it off to Cincinnati for analysis.
Since 2008, the Polar Bear Signature Project has dedicated its time and efforts to understand the reproductive cycle of the Arctic bears.
“Polar bears exhibit a unique medley of reproductive phenomena,” said Curry. “They only breed at certain times of year, ovulation is induced by breeding, they experience embryonic diapause (when, following fertilization, the embryo only grows to the blastocyst stage and then embryonic growth is arrested for months until implantation in the autumn), and females may exhibit pseudopregnancies.”
Non-pregnant female bears can experience an increase in progesterone that is indistinguishable from pregnant bears. Without an accurate non-invasive pregnancy test for polar bears, Curry says researchers can’t tell for sure whether or not a female is pregnant until she has cubs (or doesn’t). Understanding how bears breed in captivity can help explain the reproductive cycles of their wild cousins.
“Unfortunately, polar bears in the wild can be difficult to study – specifically, collecting regular, serial samples from the same individual to better understand how hormones change over a period time is extremely difficult if not impossible,” said Curry.
Because only one or two females give birth every year in captivity, the zoo’s “enormous bank of polar bear poop” provides material from both pregnant and non-pregnant bears so that scientists can find biomarkers that could indicate when a bear is pregnant, like the bear equivalent to hCG proteins found in human pregnancies. Artificial insemination was performed for the first time in a polar bear in 2012. Though no cubs have resulted from these efforts, CREW says the attempts help scientists to better understand reproductive cycles.
Polar bears are currently threatened by the impending loss of sea ice that they rely on to hunt and feed. In years of late ice freeze and early ice melt, Curry notes that bears may not be able to gain enough weight to maintain a pregnancy and raise offspring. In addition to polar bear samples, Curry writes that the program has received and analyzed samples from dozens of other species, including rhinos, cheetahs, small endangered cats, red pandas, and otters – all animals that have had difficulty breeding in captivity.