Fertility tests for Edinburgh Zoo panda Tian Tian

The tests will continue to allow experts to monitor her hormone levels and help keepers best decide when to introduce the pair again.

Pandas usually mate between March and May. However, the mating period lasts less than two days and they are kept separate for rest of the year.

Iain Valentine, director of the giant panda project at Edinburgh Zoo, said light was very important to determining when the pandas would mate.

“There will be a huge focus on working to synchronise both Tian Tian and Yang Guang’s hormone cycles,” he said.

“As seasonal breeders, panda hormones are dictated by light levels. The indoor lighting levels in their enclosures now simulate those of natural light levels, in line with sunrise and sunset.”

He said there would also be an increase in enclosure swapping, allowing the pandas to smell each other’s scent and mark in each other’s enclosures.

Mr Valentine said this was “a vital aspect, as the male can tell when the female is coming into season by the change in her scent, and the female can tell if the male is sexually mature and capable of breeding by his scent and scent marking skills.”