Edinburgh Zoo Pandas
Giant panda males are reproductively viable only for six months in a year whereas the female are reproductively viable for only one or three days in a year, according to panda researchers. REUTERS

Much to the despair of the zoo authorities and the panda lovers, the Edinburgh zoo pandas failed to mate.

Tian Tian, the female panda and the male Yang Guang, both bought from China by the Edinburgh zoo, spent the first day just playing.

Though Yang Guang was apparently showing greater aggression in the second day, Tian Tian preferred to eat and sleep than mating.

But why they failed to perform?

There are certain reasons which make it very tough to get giant pandas to mate, according to the researchers from the Smithsonian Conservation Biology Institute, who studied the panda reproduction system for the past three years.

An analysis of the seasonal changes in male panda hormone (testosterone) levels of eight male giant pandas at the Chengdu Base of Giant Panda Breeding in China revealed that male pandas are reproductively viable only for six months in a year.

The female pandas have even shorter period and are reproductively viable only for 24 to 72 hours in a year.

According to the researchers, breeding season for all female pandas lasts from February to May and they would be ready for one to three days of mating within that time frame.

Scientists also claim that the male pandas have less hormones and sperm production during the mating season. Probably this might be the reason for the failure of zoo pandas to mate.

"The males are generally very good barometers of female receptivity, and will not breed with females outside of their receptive period. Although the period of reproductive viability differs greatly between the two sexes, the researchers believe the process is quite energy efficient, ensuring that males have enough sperm when the brief and unpredictable female panda estrus occurs," Discovery News quoted Rebecca Spindler, a reproductive physiologist at the Smithsonian National Zoological Park, as saying.

"During the breeding season, the males are already decreasing these hormones, behaviours and sperm production, resulting in an abrupt end to their reproductive potential around June. These changes allow for the male to successfully mate with as many females as possible, with as little energy expenditure as necessary," said Copper Aitken-Palmer, head veterinarian at the Smithsonian Conservation Biology Institute.

Another new study, authored by a different team of Smithsonian Conservation Biology Institute scientists, found that nearly 10,000 square miles of giant panda habitat will likely be lost by 2080 as climate change causes giant panda habitat systems to shift to higher elevations and latitudes, according to Discovery News report.

This means less than half of their already decreased habitat is projected to be unsuitable in about 70 years.