Eats shoots and leaves... Scotland's pandas arrived in a blaze of publicity, with hopes high for the patter of tiny feet. But as they return to China after 12 years of repeatedly failing to conceive, was this £20m gamble EVER likely to pay off?

They looked this week like an Edinburgh couple giving each other the silent treatment. Perched outside on his wooden deck, he stoically picked at the food which was laid out all around him. He wouldn’t be apologising.

She was dining too – indoors and out of his sight. She paused for a moment, moved towards the doorway to her garden, glanced out at the dreich skies and then returned to her meal. She had nothing to say to him.

For 12 years the anthropomorphic appearance of Edinburgh’s most famous double act has tempted us to ascribe human emotions to a species which is probably not as smart as the average bear.

The truth is Yang Guang and Tian Tian the giant pandas have lived separate lives for the entirety of their time in Scotland. Neither, we have long known, has the slightest interest in the other; there was never any chemistry; they don’t even go for the same bamboo.

Had they any say in the matter, they would surely have parted years ago. Now, in late middle age, both are moving out – and away from each other.

At close of business on Thursday, Britain’s only giant pandas will bow out as the most pre-eminent animal exhibits on these islands.

We will likely not see them on Scottish soil after that.

In the days following – Edinburgh Zoo will not say exactly when – the pair will fly home to China and, soon afterwards, embark on different paths in life. There is no sense in their being together. It is late in the day but she may yet rekindle her sex life. His is over.

The pandas’ low-key departure for the old country will stand in stark contrast to their arrival almost exactly 12 years ago when crowds lined the streets of Corstorphine hoping to catch a glimpse of animal kingdom royalty.

Their private jet, dubbed the FedEx Panda Express, touched down at Edinburgh Airport to the skirl of the bagpipes. They were lowered to the ground in separate Plexiglass crates – and as Yang Guang stood up on his hind legs to cast his quizzical gaze on the welcoming party of press and dignitaries, there was a collective gasp of adulation.

Tian Tian – smaller, more circumspect – was cuter still.

Few among those of us gathered on the tarmac that day in December 2011 to record the moment doubted they made a perfect match. There was talk of imminent parenthood. Even Deputy First Minister Nicola Sturgeon was at it. ‘I know we’re all keeping our

fingers crossed for the arrival of a little MacPanda some time before too long,’ she said, moments after the star couple disembarked.

The interconnecting ‘love tunnel’ where they would rendezvous for baby-making during the small annual window when Tian Tian was in season caught the nation’s imagination. 

Some reports suggested easy listening music would be played to put them in the mood for romance – others that Yang Guang would be slipped some Viagra.

Yet, for all that they were billed as a ‘breeding pair’, the salient point was in the small print: they had each bred with other pandas. Those two eight-year-olds had never met – not even a quick hello on their 11-hour plane journey.

It has been a learning curve for us all, including the two visitors from China who are at least trained to keep their mouths open for dental checks and hold still for heart monitoring and blood samples.

Their hundreds of thousands of visitors, meanwhile, have learned that the reasons there are so few of the creatures around have little to do with familiar issues such as predation or loss of habitat.

Giant pandas have the digestive systems of carnivores yet, as we have now witnessed, spend almost all day every day eating vegetation which gives them little sustenance. 

We now know all about their under-active libidos, that they can be picky in the extreme when it comes to mating and that some – notably Yang Guang – are bamboozled by the very mechanics of sex.

In Tian Tian’s case, repeated attempts to produce a cub through artificial insemination all failed. Giant pandas, it turns out, are not good at pregnancy either.

Ultimately the two were left to do perhaps the only things they can do with real aplomb – sit upright on their bottoms like overgrown toddlers, chew on bamboo and capture hearts.

Bidding my own farewell to them at Edinburgh Zoo this week, I found them in typical pose. 

Yang Guang, the more outgoing of the two, sat with his back propped against a beam of his climbing frame, his lower half enveloped in his favourite shoots.

Periodically he sank lower into his duvet of bamboo as he reached for a fresh handful. Not a problem. He could chew lying down too.

Elsewhere in their enclosure, Tian Tian appeared – as ever –more restive, moving position several times as visitors peered through the glass of her indoor quarters. It is said her most revealing moments are when she thinks no one is looking.

Sometimes she likes to sit and watch the zebras in the next enclosure – or have a swipe at the butterflies fluttering around her nose. 

Certainly, they hold her interest more than he does. Although they can see each other outside over their dividing fence, the atmosphere has long been one of studied indifference.

It brings a bittersweet quality to the farewells which visitors to the zoo have been bidding to its star attractions over the past few weeks – an inescapable feeling that the panda experience has been a disappointment.

Over the first decade of their stay, Edinburgh Zoo paid the Chinese government around £7.5million for the privilege of ‘renting’ them. Its two-year extension to the deal cost it another £750,000 at a time when the zoo was facing annual losses of £2million.

Caring for the pair, including food and veterinary bills, came to £35,000 a month – more than £5million over 12 years. 

Their new enclosure – funded by the Scottish Government and opened towards the end of the pandas’ stay – was more than £2million.

The charity Animal Concern believes the full cost of the exercise could top £20million. 

Now, at the end of it, 20-year-old Tian Tian leaves as a veteran of multiple failed pregnancies. Yang Guang, also 20, leaves infertile. He had the snip after developing testicular cancer in 2018.

Not that the Royal Zoological Society of Scotland is ready to view the pandas’ extended sojourn on these shores as a failure.

Its CEO David Field told the Mail: ‘With more than a million species at risk of extinction and our natural world in crisis, Yang Guang and Tian Tian have had an incredible impact by inspiring millions of people to care about nature and allowed us to connect many more people with the conservation causes that RZSS is actively involved with.’

And, while the pair may never have successfully mated, he said the zoo’s veterinary and keeper teams had helped make ‘a significant contribution to our understanding around giant panda fertility, husbandry and veterinary care – which has been of real benefit to efforts to protect this amazing species in China.’

In fairness, where Edinburgh Zoo failed to produce a cub, many others have failed before. Multiple giant pandas have come and gone at London Zoo without once delivering the goods that keepers’ hearts were set upon.

During the last attempt at a natural coupling, Bao Bao and Ming Ming fought so savagely that they had to be separated – not before Ming Ming lost part of her ear.

Indeed, across Europe, only giant pandas in France, Austria, Belgium, Spain and the Netherlands have successfully lived up to their billing as breeding pairs. 

Elsewhere they have been handed back to China, as Edinburgh is doing now, with a rueful sense that the zoos could have done no more, that nature simply was not on their side. 

That was clearly the case for the two creatures due to ignore each other for just a few days more in Corstorphine.

In year one, it was the gauche male panda who seemed to be the problem. Even as Tian Tian tried to make things easy for him, he appeared not to have a clue what to do. ‘He’s a gentleman and maybe he shouldn’t be,’ said zoo keeper Alison Maclean at the time.

By year two it was perhaps already too late. Tian Tian’s signals were contradictory. One minute she was calling him towards her, the next scaring him away.

A pattern was emerging by year three. He was still interested in her, but she had rejected him.

‘She is not seeing him as the big, butch male,’ Mrs Maclean explained.

At one stage, to throw her off her unworldly suitor’s scent they sprinkled urine belonging to a more virile male panda around the enclosure. It didn’t work. These two simply didn’t click.

As the zoo’s chief executive Mr Field later put it, Tian Tian ‘wouldn’t have swiped right’ if she was using the dating app Tinder. ‘Sometimes animals just don’t get on,’ he said.

For many more years, artificial insemination was attempted too, heralding an annual ‘is she or isn’t she?’ guessing game. 

The eventual answer, invariably, was that if she ever was, she isn’t now. The closest she came was in 2014 when Tian Tian ‘reabsorbed’ her foetus late term after her body cut off the food and blood supply to the placenta.

All kinds of theories abounded both on the pair’s failure to mate and the mother’s failure to carry a cub full term At one point, leaf blowers and high-visibility clothing were banned around their enclosure in case they put the bears off.

Iain Valentine, the zoo’s former director of giant pandas, believed that fighter jets taking part in Edinburgh’s military tattoo might be responsible. 

They would fly over the zoo during August at a crucial moment in the panda’s pregnancy.

He wondered whether differences between daylight levels in Edinburgh and China may have upset Tian Tian’s hormones.

As for Mrs Maclean, she has a theory too but prefers not to expand on it. ‘For me the greatest low is it didn’t happen for her,’ she said in September. ‘It would have been the cherry on the cake for us at the zoo.

‘We know she has done it before and she was a really good mum.’

The financial consequences of the failure may be more long lasting than the emotional ones. 

In year one, visitor numbers at the zoo rocketed by 50 per cent to 810,937. By last year they stood at 601,285 visits – not much more than the numbers welcomed before the pandas arrived.

Few doubt that, had a cub come along at any point, the figures would have been stratospheric. Instead, as the zoo prepares to lose its biggest crowd pullers, its visitor numbers have dwindled almost to pre-panda levels.

‘The economics probably do not add up,’ admitted Mr Field this year.

So what happens next? How does any zoo follow giant pandas?

Mr Field told the Mail: ‘RZSS has pledged to reverse the decline of at least 50 species by 2030 and we plan to convert the giant panda habitat at the zoo to welcome a new species in the future.

‘After the pandas leave, we will decide on a new species with a crucial factor being how we can support conservation in the wild.’

It is goodbye, then, to Yang Guang and Tian Tian. They return home leaving many in Scotland as perplexed as the two of them were when they arrived.

Naturalist Chris Packham once remarked that their species had entered an evolutionary cul-de-sac. The question now is whether, in welcoming them, Edinburgh Zoo stumbled into a financial cul-de-sac. Next year’s visitor numbers could make sobering reading.

For now, the panda cuddly toys are retailing at the gift shop for between £12.50 and £32.50 depending on size. The price may drop if you wait.

j.brocklebank@dailymail.co.uk