Video: Pandas In The Mood For Love
The video here is of Edinburgh Zoo's two celebrity guests - Tian Tian and Yang Guang - just before they met for the first time.
Tian Tian has a 36 hour window of opportunity to be impregnated. The Zoo decided that the time was right to open the "love tunnel" between the two pandas, having observed Tian Tian for some days going up to the grate separating the pandas' enclosures and spending time in her pond to cool her internal system down. Higher oestrogen levels and a dip in progesterone also indicated Tian Tian was ready.
The zoo said that the bears would spend around three 15-minute sessions a day together, with keepers on hand in case there is any aggression between the two (not unknown between mating pandas).
The first meeting was encouraging with the zoo reporting that Yang Guang showed no aggression during their time together, mounting Tian Tian, and the two indulging in a spot of panda wrestling.
The pair are spending this evening together again.
Iain Valentine, Director of Research and Conservation said the zoo had "high hopes" that they will breed.
Valentine added: "If Tian Tian does get pregnant, confirmation of this may also not be straightforward. Female pandas often have pseudo pregnancies, where their behaviour and hormones indicate they are pregnant for fairly long periods of time, when in fact they're not! Also, experts do not know how long panda gestation periods actually are, as female pandas practice delayed implantation. Panda pregnancies can be anything from 85 to 100 days."
It might not be until mid-July before positive or negative results can be confirmed, he said.
"We understand that the whole country is in a state of heightened anticipation, but whatever the outcome of next week, we as animal conservationists and scientists have learnt a huge amount in such a short time about this captivating species. We are just delighted to be playing our part in in the essential long term worldwide panda breeding programme."