Giant pandas are notoriously difficult to breed in captivity. But researchers studying the mating behavior of these endangered species have discovered that copulation and reproductive rates among pandas increase by a lot when they’re paired with preferred partners. The findings, published in Nature Communications this week, suggest that simply letting pandas choose between partners could help captive breeding programs.
With populations of wild animals declining at alarming rates, we’ve increasingly turned to conservation breeding, which allows for reintroduction to re-establish or supplement dwindling wild populations. Oftentimes, conservation programs try to match males and females based on their genetic profiles to minimize inbreeding and increase genetic diversity. But this method is both costly and offers no guarantees. Not to mention, animals are typically given just a single option for a mate. But what about mate choice or mutual preference?
A team led by Meghan Martin-Wintle of PDXWildlife studied the mating behavior of about 40 giant pandas (Ailuropoda melanoleuca) at the Bifengxia Chinese Conservation and Research Center for the Giant Panda in Sichuan Province during the breeding season (February to May) of 2012 and 2013. The pandas were housed in open-air, concrete-walled enclosures arranged in a U-shape, and each enclosure had barred “howdy” windows and circular barred gates. This gave the pandas eight spots where they can interact with two potential mating partners in adjoining enclosures.
The researchers watched for pre-mating behaviors that indicated preference, including scent-marking, urination, water play, rolling, chirping, bleating, and masturbation by pandas of either sex. The team also paid attention to negative interactions, such as growling and avoidance. Males were then selectively introduced into female pens for up to 1,000 hours.
The team found that mating success and cub production are dramatically enhanced when an individual male or female showed a strong preference – directing more than 60 percent of its pre-mating behaviors towards one of the two choices. And it works even better when both pandas in a pair share a mutual preference: Ten out of 12 mating attempts were successful when both had chosen the other. Successful mating attempts rise from 0 percent, when neither individual showed a preference, to more than 80 percent when both did.
The study didn’t identify how mutual preference benefitted the pandas, though increased copulation rates and cub production suggest improved behavioral and possibly genetic compatibilities. While free mate choice won’t be a panacea for conservation breeding, incorporating mating preference trials certainly could be helpful. But if it's as simple as pairing pandas with their preferred partners, how haven’t we thought of this sooner?
"Much of it has been due to the constraints of keeping a genetically healthy population and also due to the constraints of facilities able to undertake this investigation," Martin-Wintle explains to IFLScience over email. Currently, studbook records are used to calculate relatedness, and pairs are selected to maximize maintenance of genetic diversity. "However, there are often several candidate mates that are genetically suitable," she adds, "and we believe that behavior and mate choice has a role to play for improving the success rate of breeding among genetically suitable partners."
In this video, you can see a male and a female interacting along the enclosure barriers prior to breeding introductions.
Image in the text: Xi Xi cuddles with her 2015 cub at the China Conservation and Research Center for the Giant Panda. San Diego Zoo and Meghan Martin-Wintle/ PDXWildlife
Video credit: San Diego Zoo and Meghan Martin-Wintle/PDXWildlife