#PandaStory

In 2015, the Smithsonian's National Zoo and Conservation Biology Institute keepers, scientists and researchers took to social media to give the public a behind-the-scenes look into the world of saving giant pandas.

Chapter 1: Sperm on a Plane

Let’s talk about panda sex (or perhaps lack thereof). Panda breeding season is a race against the biological clock. It only comes once a year for 24-48 hours, and our giant panda team must be ready. Our female giant panda Mei Xiang should enter estrus before the end of May. The panda team will artificially inseminate her with frozen-thawed semen. This year for the first time, our panda team may use semen collected from a male panda living in China. With only 2,256 pandas on the planet, 392 of which live in human care, genetics play a big role in breeding season. The best genetic match for Mei Xiang happens to be in China. So, what’s a scientist to do when the best genetic match for your female panda is on the other side of the world? Fly frozen semen to the intended female. For the next 24 hours we’ll bring you a behind-the-scenes look at the trip. SBCI scientist Caitlin Burrell is making the trip from the Bifengxia panda base with the cargo. #PandaStory #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 19, 2015 at 4:15pm PDT

What do you do with something as valuable as semen from an endangered species. Bank it, obvi. This is the panda sperm bank at the Bifengxia panda base. SCBI research scientist Dr. Caitlin Burrell made a withdrawal from the vaults of liquid nitrogen tanks yesterday to bring back to SCBI’s cryopreservation bank at the National Zoo. Cryobanks enable scientists to preserve 90 percent of the genetic diversity of the panda population in human care for the next 200 years. And they only have to move the frozen semen rather than a bear. #InstaScience #PandaStory

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 19, 2015 at 5:12pm PDT

The gray case is the frozen semen at the airport checking in. Check list when traveling with frozen panda sperm: 1 SCBI scientist. Several Chinese colleagues & scientists to help through customs. 1 passport and all of the official import permits. #InstaScience #PandaStory

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 19, 2015 at 6:55pm PDT

Dr. Burrell with the endangered cargo leaving Chengdu. Next up: the 13 hour trans-Pacific flight. Sperm temp. -196 degrees Celsius. Science travel pro-tip: Frozen semen can be considered a carry-on. #InstaScience #PandaStory

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 19, 2015 at 8:11pm PDT

Frozen panda semen on a plane. It gets its own storage compartment. #InstaScience #PandaStory

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 19, 2015 at 9:10pm PDT

We're still waiting for Dr. Burrell to land in the U.S. with the frozen panda semen. In the meantime for anyone wondering how we keep sperm viable indefinitely, we freeze it at -196 degrees Celsius. It potentially has a shelf-life of forever. For one successful artificial insemination, giant panda scientists need billions of sperm. Luckily, billions of sperm fit in small straws inside a liquid nitrogen tank (like these). #InstaScience #PandaStory

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 20, 2015 at 4:17am PDT

One ocean later… The sperm has landed. Next stop before the final leg of the journey: immigration and customs. To transport endangered genetic material internationally scientists needed permits from CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) #InstaScience #PandaStory

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 20, 2015 at 8:48am PDT

Our frozen panda sperm is almost here. This was Dr. Burrell's view of the final descent into Dulles International Airport! #PandaStory #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 20, 2015 at 3:06pm PDT

Chapter 2: To the cryopreservation bank!

First planes, now trains. Frozen panda semen on the shuttle to the main terminal, just like everyone else #PandaStory #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 20, 2015 at 3:31pm PDT

Next stop for our endangered cargo: the cryopreservation bank at the Smithsonian’s National Zoo in Washington, DC. #InstaScience #PandaStory

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 20, 2015 at 3:50pm PDT

For the final trip the frozen panda semen is secured upright in the back of the National Zoo police car. The container has been in an upright position for 7,000 miles. If it were on its side the temperature would have fluctuated from -196 degrees Celsius. #PandaStory #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 20, 2015 at 4:02pm PDT

We’ve arrived. The cryo-bank at the Zoo has more than 2,500 semen samples from more than 100 species. Many of them endangered.#InstaScience #PandaStory

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 20, 2015 at 4:32pm PDT

And now the panda semen can just chill out here in the endangered sperm bank. #InstaScience #PandaStory

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 20, 2015 at 4:39pm PDT

Let's Talk About (Panda) Sex

Cool, calm, deposited. Now just waiting for breeding season! Want to know how the #PandaStory turns out? Keep following, we’ll keep the updates coming through breeding season and #CubWatch! #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 20, 2015 at 5:06pm PDT

Eau de panda. Mei Xiang has been busily scent marking her enclosures. Through scent marking pandas can communicate their identity, breeding status, and location to other pandas. The oily "perfume" comes from a gland at the base of the tail. As we get closer and closer to breeding season Mei will spend more time scent marking. Behavioral cues like this help the panda team determine when she is approaching estrus. #PandaStory #WeSaveSpecies #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 21, 2015 at 1:39pm PDT

The ultimate success of this #PandaStory will undoubtedly be the birth of a healthy cub! One yard over from the commotion of breeding season, we have a living conservation success story, and her name is Bao Bao. She isn’t so little anymore, weighing in at 109.5 pounds, and according to her keepers she’s a bamboo-eating machine. Giant pandas are native to the bamboo forests of China, and they are considered an umbrella species. That means to save giant pandas, we need to save bamboo forests and all the other species that live in them— making them a great icon for conservation and #EarthDay! #InstaScience #WeSaveSpecies #HappyEarthDay

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 22, 2015 at 10:20am PDT

Did you know male pandas do handstands? Technically, it’s called urine hopping. Male giant pandas do this in addition to scent marking during breeding season. It marks their territory very clearly, telling any other male pandas in the area to keep moving. The higher the males spray the urine, the bigger the size of the odor field and the more likely a lady panda will smell it. With only 24-72 hours to mate with any nearby ovulating females, there can be no subtle hints. #PandaStory #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 23, 2015 at 10:45am PDT

Of the 52 weeks in a year, Mei Xiang and Tian Tian mostly ignore each other for probably 50 of them. When they start to communicate, the panda team takes notice. Mei Xiang is showing all the signs of getting ready to breed. She’s restless, spends time pacing and scent-marking in her yard, but then takes long naps. That tells the panda team that her estrus is getting closer, but she’s not quite ready to breed yet. As you can see here, lately when she has seen Tian Tian at the mesh she sometimes chirps, sometimes moans, and sometimes is indifferent. The keepers are listening for a bleat. When Mei Xiang starts bleating, that usually means she’s ready. #PandaStory #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 24, 2015 at 1:27pm PDT

There is just 24 to 72 hours of panda fertility once every year. It’s a short period of time that we do not want to miss. To pinpoint the best time for artificial insemination, we are testing Mei Xiang’s urinary hormones daily in our endocrine lab. Keepers use a syringe to suck the urine up in Mei’s enclosure. The sample gets labeled and sent straight to the Smithsonian Conservation Biology Institute’s endocrinology lab. #PandaStory #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 25, 2015 at 8:27am PDT

We’re monitoring Mei Xiang’s hormones around the clock to help pinpoint exactly when she is at peak fertility. Usually at our 3,200 acre Smithsonian Conservation Biology Institute in Front Royal, Va., endocrinologist Sarah Putman has set-up a mobile lab at the Zoo in DC. That allows her to get hormone data to the panda team as quickly as possible. Every urine sample keepers can get is going to Sarah for immediate testing. #PandaStory #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 26, 2015 at 8:07am PDT

Chapter 4: Sperm Meets Egg, (Hopefully)

It's not magic, it's science. SCBI endocrinologist Sarah Putman changes the color of the urine samples collected from Mei Xiang before analyzing them. The reason for the color change: she has to stop the reaction from continuing to develop in order to read the results on the spectrophotometer. The spectrophotometer is calibrated to determine color change in the yellow color range #PandaStory #InstaScience

A post shared by Smithsonian's National Zoo (@smithsonianzoo) on Apr 26, 2015 at 9:45am PDT