Despite signs of pregnancy, Adelaide Zoo's female panda Fu Ni will sadly not be welcoming the pitter-patter of tiny paws any time soon — and keepers are now investigating whether the breeding difficulties might have geographical causes.
The zoo has revealed that the giant panda has undergone either a "pseudopregnancy or a loss" following an attempt at artificial insemination using the sperm of mate Wang Wang.
Keepers monitoring Fu Ni's hormones confirmed they have returned to baseline levels, meaning she is not pregnant, and "are obviously disappointed that there will be no cub this year", the zoo said.
"Unfortunately we're not quite sure whether Fu Ni at any point was pregnant," zoo director Phil Ainsley said.
"There's probably no way for certain we're going to know whether it was what we refer to as a 'pseudopregnancy' or whether potentially there was a fetus there and it's been reabsorbed."
The zoo said in a statement that it would take time for Fu Ni to realise she was not pregnant, but that she had "taken an enrichment toy and is currently 'mothering' it as is typical of a pseudo-pregnancy".
The statement said Fu Ni's "devoted keepers who were so hopeful" have done "everything in their power to ensure her welfare throughout".
Adelaide's panda breeding window has become something of an annual event, but it has so far failed to yield cubs.
"It's always a really tough journey to go on with our giant pandas because giant panda reproduction is incredibly difficult," Dr Ainsley said.
"We know the chance of success is always very low, an animal that only has a breeding window in terms of being able to get pregnant of just once a year of between 24 and 72 hours."
North-to-south shift linked to biological clock
Wang Wang and Fu Ni are among the zoo's main attractions and arrived in Adelaide from China in 2009.
But Dr Ainsley said it was possible that the shift from the northern to the southern hemisphere had adversely impacted the animals' reproductive systems.
"These are one of only two pairs of [giant] pandas in the southern hemisphere, and when you move an animal from the northern hemisphere to the southern hemisphere, effectively its biological clock has got to completely turn around," he said.
"Breeding season in Australia is the opposite to when it is in China.
"Whilst getting a cub would be a fantastic outcome, part of the reason we have them here in Australia is to actually understand the implications on their reproductive systems in an entirely different hemisphere."
The zoo said while Wang Wang would remain on show, Fu Ni would take some time out of the public spotlight.
"She will also continue to require her own 'off display' time to allow her hormones to settle and for her to come to the realisation that despite what her body has told her, she will not be giving birth to a cub," the statement said.
In 2019, a deal was reached to secure the pandas' ongoing presence at the zoo until at least 2024.
"We currently have a loan agreement in place with the [Chinese] government and, at the moment, that comes to a conclusion at the end of next year," Dr Ainsley said.
"We'll start to have conversations with our counterparts in China to see what the season looks [like] ahead in terms of the breeding year, the 2023 and 2024 breeding year, and then work out how we approach that."
Dr Ainsley said pandas had recently been reclassified by conservationists as "vulnerable" rather than "endangered", which he said was "testament to the global effort in trying to conserve giant pandas".
In December last year, a minor safety breach occurred at the panda enclosure when a school student climbed in to retrieve a mobile phone.
