Panda sex: pick your partner

Animals are not human, but humans are animals. And some animals behave more like humans than previously thought - like giant pandas, when it comes to sex.

Just imagine someone else choosing your sex partner for you. He or she would be the best you could get - at least, relating to the mix of your genes and the offspring you two would produce. You could sleep with this partner - or forget about sex altogether. That would suck, huh? A giant panda might think the same.

In zoos and other giant panda breeding facilities, the breeder typically arranges mating pairs. He aims to minimize inbreeding and maximize reproduction rates.

That all comes down to the genes - and a bear's individual preferences are not part of the process. But they should be, Meghan Martin-Wintle of San Diego Zoo and her fellow researchers write in the journal "Nature Communications".

Aroused pandas

The researchers introduced to each other giant pandas who lived at the Bifengxia Chinese Conservation and Research Center for the Giant Panda in the Sichuan province of China.

They documented which male-female pairs seemed to hit it off, and which ones didn't. Signs of liking each other included scent-marking, water play, rolling, urination and interaction with the opposite sex of their species, Martin-Wintle and her fellow researchers write. Other obvious signs were masturbation and penile erections.

Dislike, on the other hand, displayed itself in physical attacks, lack of interest, moaning, barking and growling.

After having recorded which bears like each other and which ones obviously can't stand each other, researchers put together mating pairs according to the best genetic mixture - as is usually done - and then observed what happened.

More sex, more babies

Giant pandas that were taken with each other had sex twice as often as pairs who didn't like each other. Well, the researchers call it "successful intromissions" but they mean "sex." Preferred pairs, as they put it, mated in 72 percent of all cases; non-preferred pairs in only one-third of all cases. Many of these chose not to have sex at all.

Giant pandas that like each other had about one and a half times more babies than those that don't like each other. Panda love translates into 1.4 cubs, in comparison to 1 cub on average per pairing.

Typically, giant panda mothers give birth to one or two cubs. If pairs don't mate at all, they don't produce offspring - and that lowers the number of cubs and overall birth rate.

"If managers were to incorporate mate preferences more fully into breeding management, the production of giant panda offspring for China's reintroduction program might be greatly expedited," Martin-Wintle and her colleagues conclude.

Let them choose!

When breeders brought together pandas that seemed to hate each other, in a third of these cases, the pandas mated anyway. And they gave birth to cubs. That might lead to the assumption that personal preference is not that important in the sex life of a giant panda.

For breeding programs, it is crucial to pair those animals that are genetically well-suited for each other, in order to avoid hereditary diseases among those rare animals. China's giant panda breeding program aims to produce enough pandas to be able to reintroduce them into the wild and reestablish or supplement wild populations. They have to be absolutely healthy.

The researchers' suggestion: determine which partners are genetically suitable - after that introduce these animals to each other, and let the pandas choose. That "makes it possible to have the best of both worlds."

The research is not only applicable for giant pandas - it'll help in the breeding programs of other endangered species as well, researchers say.

A reputation of being sex-lazy

A recent survey estimated that 1,864 giant pandas live in the wild. The good news: these numbers are on the rise, 268 animals more than in the last survey published about a decade ago. Still, these numbers are worrisomely low.

It is often said that giant pandas breed very slowly, and that they are lazy about mating.

"That is only a legend," Arnulf Köhncke of the World Wide Fund for Nature had told DW in the past. "Giant pandas do not reproduce less effectively than other bears."

Experts say that legend has taken hold because it is hard to breed pandas in captivity - female pandas won't accept just any male. Moreover, they are only fertile for about 36 hours a year.

Zoos have only 36 hours to introduce a sex partner to a female so they will mate.

If that doesn't work, artificial insemination is the only option left - an expensive procedure that is no fun for the bears.

All the more a reason to give pandas a say in their own sex life.