After three days of speculation, tension and excitement, a zoo announced Thursday that Scotland's only pandas -- Sweetie and Sunshine -- had failed to mate.

Normally kept separately, they were only introduced to each other Tuesday, but the signs looked good.

"Gentle giant" Sunshine, or Yang Guang, had been doing "panda handstands" to display his virility, while "very smart" Sweetie, or Tian Tian, also seemed interested.

In a brief emailed statement, Edinburgh Zoo said they noticed a drop in Sweetie's hormones late Wednesday and "limited breeding behavior was seen in both pandas" Thursday morning.

"As a result Tian Tian and Yang Guang were not put in together today [Thursday]. Edinburgh Zoo can announce that the panda breeding season for 2012 has now come to an end and both pandas are back on display," the statement said.

Lack of mating experience hinders Scotland's pandas

There was perhaps a note of sadness in the final line of the email, which was sent to msnbc.com and other media outlets. 

"No interviews will be given today and there’s no access on site."

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Canada's Prime Minister Stephen Harper looks at a panda being held by his wife Laureen at a zoo in Chongqing, China, Saturday.

China is to send two giant pandas to Canada, it was formally announced Saturday, as Prime Minister Stephen Harper hailed the "mutual respect" and "goodwill" between the two countries, according to a report.

The pandas, Er Shun and Ji Li, will be housed at Toronto and Calgary zoos for five years and cost more than $1 million a year, the Winnipeg Free Press reported.

Adrian Wyld / AP

A baby panda appears to offer a paw to Canadian Prime Minister Stephen Harper.

"Canada and China enjoy a strategic partnership based on mutual respect and collaboration," Harper said at a zoo in Chongqing, as Er Shun ate bamboo in the background, the Free Press said.

"Our mutual love for pandas is one more example of the goodwill that underlies the relationship between Canada and China," he added.

Harper, along with his wife Laureen, were allowed to hold and pet a four-month-old panda, ahead of the announcement.

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AP

Retired NBA basketball star Yao Ming holds a panda during a ceremony for the release of six pandas in the Panda Valley natural reserve in Dujiangyan, in southwestern China's Sichuan province on Wednesday.

BEIJING – Retired NBA star, Yao Ming, carved out an eight-year career protecting the hoop in the NBA. His next defensive assignment though may be a considerably taller task for the 7’6” all-star, if not a lot cuter and fuzzier than his former basketball opponents.

Yao was in the central Chinese province of Sichuan on Wednesday, where he presided over the opening of a new phase in the giant panda-breeding program that some experts hope will help pandas born in captivity eventually assimilate back into the wild through a regimen of acclimation and survival training. 

“I think it is most important to keep a balance between modern living and nature,” said Yao to reporters in Sichuan. “We have been talking about it for many years but it is never an easy thing to do.”

China Photos / Getty Images Contributor

Giant Panda "Yingying," eats bamboo at the enclosed Panda Valley natural reserve after being released into the semi-wild in Dujiangyan, Sichuan Province, China on Wednesday.

Chinese experts constructed a $4.75 million habitat called “Panda Valley” in the area around the town of Dujiangyan – a place heavily hit by the 2008 Sichuan earthquake. The 50-acre park will serve as a large, open-area school where researchers will be able to slowly teach the pandas the art of survival in the harsh, elevated mountain wilderness that pandas thrive in.

Over time, organizers plan to expand the panda habitat to eventually allow for up to 30 pandas to live there. It is hoped that eventually 100 pandas from this facility will be released back into the wild over the next 50 years.

Panda researchers in China screened the 108 pandas in captivity at the Wolong Panda Reserve in Sichuan over the period of a year and whittled the list down to six final candidates. The roster included such panda celebrities as twin brothers, Xingrong and Xingya, and one panda named Gongzai, who was the inspiration for “Po” the rotund, fighting panda featured in the “Kung Fu Panda” movies.

These pandas were selected for this pilot project based on criteria that encompassed age, health and genetic background. 

It is hoped that the pandas selected will demonstrate the best combination of strength to defend themselves from wild pandas, while being young enough to allow them the opportunity to grow up and adapt to their wild surroundings.

The ultimate goal is for these pandas to grow up, assimilate into the wild and give birth to new pandas ready to survive in the wild.

China Daily / Reuters

Former NBA player Yao Ming and his wife Ye Li play with giant panda cubs at the Chengdu Research Base of Giant Panda Breeding in Chengdu, Sichuan province, on Wednesday.

The preserve’s opening comes as China is in the midst of a nationwide panda census that is conducted every ten years. There are an estimated 1,600 pandas living in the wild and an additional 300 living in captivity.

Despite China being at the forefront of panda research and the masters of a highly successful breeding program, some experts feel that the park is simply too expensive and that previous attempts to create similar preserves for other species have come with mixed results.

A similar attempt to reintroduce pandas back into the wild in China ended in failure in 2007 when Xiang Xiang, a five-year-old male panda trained for three years by researchers was found dead after he was killed by wild pandas.

Related link: Six pandas amble toward freedom in China preserve