The giant panda love affair appears to be heating up – after zoo bosses revealed female Tian Tian has “gone off her food” and “become a bit temperamental”.
Far from being a worry however, experts believe this indicates that she is beginning to warm to her mate Yang Guang.
In recent weeks keepers have been watching the pandas with a view to knowing exactly when the 36-hour window of opportunity for breeding arrives.
Hormone samples are being taken to Chester Zoo on a daily basis for testing to ensure the two pandas can be put together at just the right time.
Iain Valentine, director of giant pandas at Edinburgh Zoo, said: “So far we’ve been encouraged by both pandas starting to show breeding behaviours much earlier when compared to 2012, which is a sign that they’re nice and settled in their home in Scotland.
“Tian Tian’s behaviour has started to change a lot over the last couple of days. She’s become grumpier, has gone off her food and has become a bit temperamental – basically a different panda to how she normally is.”
Tian Tian and Yang Guang have both bred before, although not with each other.
Breeding in captivity has become vital to the giant pandas’ survival because of the destruction of bamboo forests in China and south-east Asia.
Mr Valentine added: “Tian Tian has shown hormone fluctuations a couple of times that suggested we were about to see a hormonal crossover that then tells us the 36-hour breeding window is ten to 14 days away.
“We’re still to see this indicator and expect it imminently in the test results we receive back from the Centre for Integrative Physiology at the University of Edinburgh first and then from Chester Zoo – who both analyse samples of Tian Tian’s urine collected twice a day, every day.
“The strong behavioural changes seen already in Tian Tian do suggest things are about to start to happen, we just need to wait and see.
“The giant panda breeding season peak is normally mid-April and into May, so this is really still only early days.”
Once the important 36-hour window arrives, Tian Tian and Yang Guang will meet several times to have the opportunity to mate and then, as Tian Tian finally ovulates, artificial insemination will also take place.
If Tian Tian does fall pregnant, it will be the second half of July or early August when Edinburgh Zoo experts will be able to tell by using ultrasound scans.
The majority of giant panda cubs are then born at the very end of August or beginning of September.