Scientists are currently carefully measuring the behaviour of Tian Tian to pre-empt the 36-hour fertility window - a window that only occurs once a year. When the day-and-a-half of opportunity arrives, male panda Yang Guang will be placed in the same enclosure as the female panda numerous times in the hope that the two will mate. Scientists will also attempt artificial insemination to try and achieve a successful pregnancy in Tian Tian.

Zoo workers have been using a number of techniques, including urine testing and artificial lighting controls, to help ensure the breeding cycles of the two pandas are closely synched.

Speaking to The Courier, Iain Valentine of the RZSS said "the next steps are to continue behavioural observational and hormone testing to confirm when the annual window has arrived."

The zoo's two giant pandas - an endangered species, recognisable by their distinctive black patches - are the only two to have lived in the UK for 17 years. They were moved to Edinburgh in 2011 on a ten-year loan from China. They are part of a decade long research project between the two countries, with a goal to ultimately re-introduce members of the species into the wild (the current wild population is estimated at around 2,000 individuals). The Scottish climate is similar to bears' native habitat of Sichuan Province, and conducive to bamboo growth.

Both Tian Tian and Yang Guang were born in August 2003, a mere ten days apart from each other. While Tian Tian has previously given birth to twins, it was not with Yang Guang.