Researchers were worried Colin would miss her annual estrous cycle which only lasts for three days. The estrous cycle is the changes which occur during the "breeding season" of most female mammals.

So the researchers decided to play Colin the video. She watched it "with great interest", one scientist said. Colin attentively studied the video standing up, then lying on the floor - without turning away. After watching it, Colin proved to be quick learner.

This was the first time the centre used video training to help a female panda, researchers said. 

Spring is the season when pandas experience their only estrous cycle of the year. Captive-bred pandas tend to be pampered and less physically active. This often make breeding difficult, researchers explained.