In this photo released by the San Diego Zoo taken Monday Dec. 21,2009 showing Giant Panda mom Bai Yun playing with her four-and-half-month old baby boy, Yun Zi, at their enclosure at the San Diego. Yun Zi has been reluctant to leave the comfort of his den, but Monday's successful venture outdoors means it is likely that within a month the cub will go on exhibit to the public.