TODAY | July 31, 2013
>> much. a lot of excitement at the national zoo in washington this morning. part of the panda house is closed because apparently one of it's guests maybe expected. kelly o'donnell has that story. kelly , good morning.
>> reporter: good morning, savannah. after the world's joy over the royal baby, just wait. there is real excitement here among zoo visitors and panda experts about the possibility of a new giant panda cub. there's only four zoos in the u.s. that have giant panda . all of them on loan from china. there's excitement about a new arrival in 40 to 50 days.
>> reporter: great expectations. one of washington d.c. 's most famous couples.
>> they're cute and neat and the kids love it.
>> reporter: giant pandas could, and we must stress could, have a new addition on the way.
>> it's exciting because baby pandas are adorable.
>> reporter: smithsonian's national zoo panda cam gives everyone a 24/7 glimpse but mother nature is mysterious and false pregnancies are common. they made a video showing an ultrasound machine done on her. zoo keepers are collecting clues like a spike in her hormones last friday.
>> you can't tell from her behavior. the only way is she either gives birth or you might get an ultrasound imagine.
>> reporter: this potential happy news is all the sweeter after the sudden death of her newborn last september. the zoo hoped to try again. skip the panda romance, she was artificially inseminated in march. maybe we'll see a baby panda boom just two weeks ago zoo atlanta welcomed twins.
>> there haven't been twins born in the u.s. for 25 years.
>> reporter: back in d.c., the father seems unphased inside the panda house where the den will be kept out of public view. she is more noise sensitive so the zoo is asking for quite. she may be harder to see for awhile but visitors can get their fill of panda bears , panda everything in the souvenir shop. and the panda exhibit here does remain open. it's just the part where she will be denning that will be closed and that big shhh sign tells everybody to keep it down. there were only about 1600 pandas around the world which makes this possible arrival all the more special. savannah.
>>> very exciting. kelly o'donnell at the zoo in washington. thank you very much.
>> the definition of a nanosecond is the time between giving birth of a little panda and somebody describing it as being the size of a stick of butter.
>> they are tiny.
>> look how cute.
>> quite. she is sleeping.
>> invading her privacy.
>> she needs her pregnancy rest.
>> we don't know if she is pregnant.
>> she requested pickles and ice cream .
>> we shall find out.