Edinburgh zoo says its experts have found it very difficult to follow Tian Tian’s hormone levels as hopes of live birth fade
Edinburgh zoo has admitted there is confusing medical evidence about the pregnancy of their giant panda Tian Tian, as hopes of a live birth began to fade.
The zoo’s panda experts and senior executives originally predicted that Tian Tian was likely to give birth in late August or early this month, producing the first panda cub for a British zoo and a major coup for the Royal Zoological Society of Scotland.
The zoo had confidently predicted a cub would likely be born by the end of last week unless she was experiencing a pseudo-pregnancy.
But it is now 56 days since Tian Tian had the surge in the progesterone hormone on 15 July which signalled she could be pregnant. Three months earlier, in April, she had been artificially inseminated with sperm from two pandas – her erstwhile mate at Edinburgh Yang Guang, and that of a dead donor male.
In a statement which said the prospects of a cub were now only “possible”, the zoo has admitted that its experts have found it very difficult following Tian Tian’s hormone levels and may have misread them in the first place.
But with many of the world’s foremost panda experts gathering in Edinburgh for a symposium on wild panda conservation organised by the zoo, due to start on Tuesday, staff there are hoping to get extra help monitoring her condition.
“In terms of Tian Tian’s possible pregnancy, we’re not out of the game yet although she’s keeping us on our toes. Her hormones are following an atypical pattern, with lots of rises and dips, which make timings much harder to predict,” a spokeswoman said.
She added that the zoo’s Chinese experts, Haiping Hu, who flew in from the China Conservation and Research Centre in Wolong, now believed the bear may have had her second significant hormone spike, which would show an embryo has been implanted, two weeks later than they had thought.
“Predicting pregnancy in giant pandas isn’t straightforward and we’re all rapidly learning that Tian Tian is a panda whose behaviour and physiology appears to be more complicated than most,” she added.
Henry Nicholls, author of the study of panda breeding programmes, Way of the Panda, said he thought it much more likely Tian Tian was not pregnant since her condition had now gone well beyond the average times for a birth.
He said one study in 2010 found the average birth date came less than 40 days after implantation. On that timescale, even a two week delay would lead to a birth about now.
“We were told that Tian Tian’s progesterone levels had undergone a significant rise on 15 July. A panda will typically give birth within 40 days of this and her rise in hormones is enormous, usually an order of magnitude so it’s odd that we are now told the rise may have happened two weeks later,” Nicholls said.
“It’s certainly possible that Tian Tian is unlike any other panda that’s been studied. Or, more likely, she isn’t pregnant. If they’d tell us what her progesterone levels are, we’d have a better idea what’s going on. Once they reach zero, then we can be confident she is not pregnant.”
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