Elvis has spent the past three weeks sniffing fecal samples from polar bears around the country, making his predictions on which bears might be pregnant. Elvis is trained to pause and sit immediately when he detects a pregnancy—and does not show interest at samples from non-pregnant bears. Last week, Elvis was presented multiple times with two separate samples (collected on 10/12/13 and 10/20/13), from the Cincinnati Zoo’s female polar bear, Berit. Unfortunately, Elvis did not show interest in either sample, indicating she may not be expecting cubs this fall.
The sniffer dog project is part of a larger effort to study reproduction in polar bears. Scientists at CREW have been monitoring polar bears since 2008 and have analyzed over 14,000 fecal samples from 55 polar bears living in North American zoos. In addition to the Elvis test, we’ve been measuring Berit’s fecal hormone levels and performing ultrasound examinations in attempts to gain more information about her pregnancy status. Taken together, it seems that Berit is probably experiencing a pseudo-pregnancy, also known as a false pregnancy. Pseudo-pregnancy occurs when a female’s hormones, namely progesterone, increase to levels similar to those of a true pregnancy. However, in a pseudo-pregnancy, no fetus is present. Like pregnant bears, pseudo-pregnant females often gain weight (Berit gained almost 200 pounds this season!) and may behave like they’re pregnant, building nests and spending more time in their dens.
We’re not sure why pseudo-pregnancy occurs in polar bears but it seems to be a common phenomenon in many females we’ve monitored. A goal of CREW’s polar bear research is to develop a test to differentiate pseudo-pregnancy from true pregnancy. If Elvis proves successful, the next step is to identify the specific compound in the fecal samples that Elvis is signaling on and then develop a laboratory-based method to measure it. A test that distinguishes pregnancy from pseudo-pregnancy could potentially be applicable to other species that experience pseudo-pregnancy, such as endangered cat species, otters, and red pandas.
Since the sniffer dog project is still in the testing phase, we are not making any major management changes based on Elvis’s predictions. Berit’s keepers continue to keep a close eye on her and she still has access to a den and extra bedding if she wants it. Berit has never produced offspring, so while Elvis’s predictions are disappointing, they are not a total surprise. Berit is of prime reproductive age for a polar bear (14 years) and we have not lost hope that she may have cubs next year!