Reuters is reporting that Tuan Tuan and Yuan Yuan are not pulling the crowds as they first were. Around 5,000 to 8,000 visitors are seeing them each day.

The reasons put forward are :
Limited interest. (Some people aren't interested in Giant Pandas. That I don't under stand :) )
People fear that the crowds will be too big so aren't visiting.
Unfavourable weather.
No school holidays.

We'll just have to see what happens when the schools break up. At least the pandas get a bit of peace and quiet.