Why is it so hard to get a panda pregnant? As many of us were saddened to find, Edinburgh Zoo’s own panda Tian Tian was confirmed not pregnant after briefly showing signs early this September. It is thought that the foetus may have been reabsorbed despite being expected to develop to full term, and offers an insight into how difficult this species is to breed. Panda pregnancies have always been a fragile affair, but offer a unique twist on what we would consider normal pregnancy. Once the egg has been fertilised, it will float around the reproductive tract for varying amounts of time before implantation occurs, which gives the panda ultimate control over when her cubs will be born ¹. The amazing thing about this is that the egg can float around in this way for a whopping 4-5 months! It certainly gives the keepers a hard time confirming the pregnancy, as at this stage the egg is in a resting state (in which the foetus does not develop) so technically the pregnancy hasn’t happened yet. If the mother decides the timing is right and conditions are good, the egg will finally implant. From there it is only roughly a 50 day developing period until the cub is born. Seven inches long, blind and completely reliant on their mother, they continue to develop for several years before striking out on their own. However, where it gets even trickier is that female pandas can often show all the signs of pregnancy without actually being pregnant (called pseudo-pregnancy). Now we can begin to see why zoos and captive breeding programmes have such a hard time keeping the population of pandas at a steady level.

Panda pregnancy still has many unknowns, but research into the reproductive systems of these gentle giants is helping breeding programmes worldwide. In the wild, however, most conservationists would agree that it is lack of habitat hindering panda populations rather than failed pregnancies. This has led to widespread critique of captive breeding programmes, with many citing that this money should go instead towards the prevention of logging and other destructive practices. The programme at Edinburgh Zoo on the other hand also includes a full research plan which aims to improve conservation of wild pandas and habitats, as well as their captive counterparts. It is thought that Giant Pandas can take up to three years to reproduce successfully in a new captive environment. Edinburgh’s pandas have been at the zoo since December 2011, so it can only be hoped that Tian Tian will go on to produce some beautiful cubs in the next few years.

Edited by Debbie Nicol

1. Zhang H, Li D, Wang C, Hull V. Delayed implantation in giant pandas: the first comprehensive empirical evidence. Reproduction. 2009; 138(6): 979–986 Available here.