Copenhagen Zoo’s female panda is not pregnant again

Copenhagen Zoo’s seventh attempt to produce panda cubs has failed, despite trying artificial insemination for the first time. Mao Sun, the zoo’s female panda, is not pregnant this year either.

The zoo had hoped the new approach would change the outcome. Zoological director Mads Frost Bertelsen said the insemination process and its timing had looked promising, but stressed that uncertainty is part of panda reproduction because the process is complex.

Xing Er and Mao Sun arrived in Copenhagen from China in 2019. Until this year, the zoo had tried to get the pair to reproduce naturally, without producing any cubs. It then chose to inseminate Mao Sun instead. The zoo said artificial insemination is a well-established method, but does not guarantee pregnancy. Experience from Chinese breeding centers suggests the chance of pregnancy through insemination is about 40 percent.

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We naturally hoped for a different result. This year we tried insemination as a new measure, and both the process and the timing of the insemination looked promising. But we also know that uncertainty is part of the process, because reproduction in pandas is complex.

The timing also makes panda breeding difficult. A female panda comes into heat only once a year, often for less than 72 hours. The zoo said Mao Sun is doing well and will now assess what it learned from this season. Bertelsen said each breeding season provides important knowledge for the animals and international conservation efforts, adding that producing cubs is central to a panda’s biological and behavioral needs.

A female panda can enter a den and experience a pseudopregnancy even when she is not pregnant, making it difficult to determine the result with certainty until late in the process. The two pandas in Copenhagen are leased from China for roughly 100 million kroner. Pandas have reproduced in captivity at zoos in several other European countries, including Germany, France and Belgium.

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This season has given us a number of valuable experiences. Working with pandas is a long-term effort, and each season contributes important knowledge that benefits both the animals and international conservation efforts.