This panda update was written by keeper Nicole MacCorkle.

We still don't know if Mei Xiang is pregnant or pseudopregnant. (Remember her hormones and behavior will mimic a pregnancy even if she is pseudopregnant!) If you have been regularly watching the panda cams, you may have noticed that Mei Xiang has pulled some bamboo into her den over the last few days. However, it is likely too early to call this true "nest-building." It's been two months since the artificial inseminations. Historically, Mei usually doesn't start nest-building so soon after an artificial insemination. In the past when we saw this behavior from Mei for a few days, or even a few weeks, she often dashed our hopes by defecating in the den. If she defecates in the den, Mei Xiang herself doesn't consider the area to be a true nest yet. A panda would never soil her nest once established, so that remains our true test. Another explanation could simply be that Mei Xiang wanted to enjoy the peace and quiet of her den. Either way, we simply have to wait a little while longer to find out if Mei Xiang considers this to be a real nest. And then, we still have to wait to find out if she's pregnant because a female would build a nest if she's pregnant or pseudopregnant! In the meantime, it couldn't hurt to think positively and keep our fingers crossed, right?!

In the next habitat over, Bao Bao got some special enrichment on Tuesday when it was extremely hot. Our giant pandas always have access to chilled areas and misters in their yards to keep them cool, and their indoor enclosures are air conditioned. But, sometimes keepers will give them enrichment items to help keep them cool as well. Bao Bao got a bear-sized ice cube, which she promptly rubbed all over herself. The panda cams caught her playing with the ice.

Summer has arrived and #PandaStory continues! We still don?t know if Mei Xiang is pregnant or pseudopregnant. (Remember her hormones and behavior will mimic a pregnancy even if she is pseudopregnant!) Over the last few days Mei has started dragging bamboo into her den, but keepers think it?s too early to call this true ?nest-building.? In past years she has dragged bamboo into her den, but days or weeks later given keepers a clear sign that she?s not actually nest-building by defecating in her den. When she starts to nest-build for real, she?ll keep the den clean. Building a nest is one of the things Mei Xiang will do if she?s pregnant or experiencing a pseudopregnancy, which is why our vets conduct weekly ultrasounds. Mei had another ultrasound on Tuesday, so our panda team can track changes in her reproductive tract. The only way to definitively determine if a panda is pregnant before she gives birth is to see a fetus on an ultrasound. But they haven't seen anything yet!

A photo posted by Smithsonian's National Zoo (@smithsonianzoo) on Jun 26, 2015 at 12:47pm PDT