Visitors at the Madrid Zoo-Aquarium could soon be hearing the patter of tiny black-and-white feet. Zookeepers say that there is reason to believe that their female giant panda, Hua Zui Ba, might be pregnant again.
It is nearly three years since Hua Zui Ba and her mate Bing Xing had their last brood of cubs, Po and De-De.
"Everything seems to indicate that she is pregnant again. Her behavior is changing - she has less appetite and she is more restless," says zoo veterinarian Eva Martínez, adding that hormonal analysis also points to a new pregnancy.
However, Hua Zui Ba's keepers will not know for certain whether or not she is expecting until they are able to conduct more tests; panda fetuses only show up on ultrasound during the last two or three weeks of pregnancy.
Giant pandas are a species in which reproduction is not easy"
A brother or sister for Po and De-De would be very important for conservationists. Pandas are an endangered species, partly due to deforestation and other human infringement on their natural habitat. Breeding pandas in captivity is notoriously difficult. Female pandas are only fertile for around two or three days a year, making conception a tricky business. Dr Martínez estimates that only about 25 to 35 panda cubs are born in captivity each year — most of them in China.
"Giant pandas are a species in which reproduction is not easy," she explains. "There are few individuals and in some cases the males do not show interest in the females. We have to draw upon techniques of artificial insemination. The difficulties are that a lot of the time natural mating does not happen between panda partners," she says, adding that pandas are also prone to "pseudo-pregnancies," which show the same symptoms as a genuine gestation.
"We work with highly specialized teams and personnel, with very high standards of food quality, welfare, care and supervision. This, together with the artificial reproduction techniques, allows us to have success in breeding."
Last month Zoo Atlanta announced the surprise birth of two panda cubs and Edinburgh Zoo also recently announced the UK's first possible panda pregnancy.
Some other zoos around the world have resorted to unusual techniques to persuade pandas to mate, including giving the male pandas Viagra or showing them so-called "panda porn" - videos of pandas mating to get the animals "in the mood."
"All the employees at the zoo are very hopeful about the possible arrival of new panda babies this year," confirms the vet.
When Po and De-De were born, they took it in turns being with their mother and being on an incubator, swapping around every three or four hours. This mimics natural behavior in the wild, where the mother would naturally choose one cub and leave the other.
Dr Martínez was present at the birth of the two previous cubs. "It was very exciting. It was very important for the conservation program of this endangered species. And when we saw the birth of the first baby, and after a while the second, and she cared perfectly for the offspring, it was very special for the whole zoo team. If this year one or two cubs were born, it would be great for the species and for the zoo."