Interesting article in (edited - my mistake - saturday's Guardian) mag - apparently the Chinese are helping these creatures make more babies.
It seems the female panda is only fertile of 72 hours a year, and pandas are very choosy about their partners. So they put an attractive female panda in the breeding pen, and when the male has decided she's a bit of a smasher, they snatch her out, and push an ugly one in, rear-end first. After the love-struck male has performed his passionate duty and climbed off, when he sees her face and realises who it is, he gets very angry at the cruel trick.
Alternative methods are even worse
for the male.http://environment.guardian.co.uk/conservation/story/0,,1966664,00.html#article_continue
http://www7.nationalgeographic.com/ngm/0607/feature1/multimedia.html