Two of Hong Kong's four giant pandas, Yingying and Lele, have turned four years old, making many panda watchers hopeful that they will now start breeding. The two pandas celebrated their birthdays at the Ocean Park Resort.

With names meaning "abundance" and "happiness," the pair were treated to an ice birthday cake in their new enclosure complete with snow, a waterfall, and a river. The male/female pair were born in August 2005 at China's leading Panda Conservation center in Wolong, Sichuan province. The Chairman of their new home in Ocean Park, Allan Zeman, says the two have lived up to their names.

Allan Zeman, Ocean Park's Chairman, said, "The way we saw them jumping on top of each other and playing with each other...it was just incredible to watch. They are so well mannered, well tempered. They really, really get along together. I am hoping as time goes on, that they will be able to continue to grow off one another."

The pandas were flown to the Special Administrative Region from the Chinese mainland two years ago to mark the 10th anniversary of Hong Kong's return to the motherland. The pair were selected from a batch of 15 cubs, based on criteria such as fertility, health, looks and social compatibility, to boost the chances of them breeding. Four is the age pandas can start mating.

Hong Kong's two other resident pandas, Jia Jia and An An have yet to breed since arriving in 1999. A bamboo park in southern China has been enlarged to provide the bamboo needed to feed the four pandas.