Zoo officials hope the mating will bring a pregnancy later in the year for Ying Ying. The zoo said the gestation period for giant pandas ranges between 72 and 324 days, though the World Wildlife Fund puts the gestation period at 95 to 160 days.
The zoo said a pregnancy can’t be detected on an ultrasound until 14 to 17 days before birth.
“The successful natural mating process today is extremely exciting for all of us, as the chance of pregnancy via natural mating is higher than by artificial insemination,” Michael Boos, Ocean Park’s executive director in zoological operations and conservation said in a statement.
“We hope to bear wonderful pregnancy news to Hong Kongers this year and make further contributions to the conservation of this vulnerable species.”
Giant pandas held in captivity around the world take part in breeding programs to boost their population. For years, the species was considered “endangered” and only recently was recategorised as “vulnerable” by the IUCN Red List of Threatened Species.
Pandas reach sexual maturity between ages 5 to 7, Ocean Park says. Ying Ying and Le Le arrived in Hong Kong in 2007, but failed to mate naturally since attempts began in 2010.
Beginning in late March, Ying Ying began playing in the water in her habitat more often as Le Le was “leaving scent-markings around his habitat” and looking for Ying Ying’s scent, the zoo said.
“Such behaviours are consistent with those common during breeding season.”
Pandas in general are solitary and can be aggressive toward each other when in the same space. However, according to the San Diego Zoo in California, there are two exceptions: mating season and mothers with cubs.