It's literally a case of there is no time like the present for the two giant pandas at Adelaide Zoo who have begun mating calls as their breeding window only lasts about 36 hours.

Zoo staff are hopeful that Wang Wang and Funi will bring a little panda into the world as Funi's high-pitched sounds are said to be typical of a female panda undertaking mating behaviour.

Now that the pair are sexually mature, experts are more confident than ever as they predict Funi will ovulate within the next 24 hours with her playfulness increasing - especially in the water.

If Funi successfully falls pregnant, which wouldn't be detected until about two weeks before birth, it will be the first time a panda is born in the Southern hemisphere.

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The pandas have been placed in each other's enclosures for periods of time to develop their scent-marking behaviour

Wang Wang and Funi have about a 36 hour window to breed once a year at the Adelaide zoo

Zoo staff says the pair are now sexually mature after being at the zoo since 2009

After artificial insemination was attempted last year, the zoo handlers and the team of specialists have decided to just try the natural breeding this time around.

Adelaide Zoo vet David McLelland said staff were the most confident they had been that the pair will breed since the pandas arrived at the zoo from China in 2009.

'They are sexually mature now - we have seen them go through puberty and develop over the last five years since they have been with us,' he told Daily Mail Australia.

'Last year we were still seeing relatively immature behaviour from Wang Wang so we didn't have any confidence of natural breeding.'

Funi's behaviour of late has also been a positive sign.

'She has had an increase of vocalisation and a lot more water play and splashing around rather than being up in the trees - they often only come down when they are receptive,' he said.

Funi's high-pitched noises are a sign that she is getting ready for the breeding season

Experts predict Funi will ovulate within the next 24 hours judging from hormone testing taken

Funi's playfulness is another sign that she is getting ready for the short mating season

After putting the pair together for a short unsuccessful period last year, the staff tried artificial insemination.

'Although we saw better signs from them we didn't think putting them together would result in anything, so we tried artificial insemination but it wasn't successful because his sperm count quality wasn't great.'

But this year is looking the most positive yet in the five years that the pandas have been living in Australia, as Wang Wang is now nine years-old and Funi is eight.

'We have progressively seen maturity in her and the male looks like he know more what's hes doing as well,' he said

'So we are a lot more hopeful and we are maximising the opportunity to breed naturally, and if we are not successful this year it will stand us in good stead for the future.'

To give the process a little helping hand, the pandas are put in each other's enclosures for periods of time.

'We move them to swap scents from one enclosure to another so their pheromones will be going haywire,' he said.

'When they are exposed to the scents of the opposite sex then it really helps them develop sexually as well.'

Dr McLelland said it was not known why pandas had such a small breeding window.

The pandas are on loan from China for another four years.

If Funi successfully falls pregnant, which wouldn't be detected until about two weeks before birth, it will be the first time a panda is born in the Southern hemisphere

Funi has four more years to fall pregnant in Australia before heading back to China