Thousands of excited fans flocked to a Thai zoo on Thursday to celebrate the first birthday of Moo Deng, the adorable baby pygmy hippo that has become a social media sensation. (AP video: Tian Macleod Ji)

Baby pygmy hippo sensation Moo Deng marks first birthday, AP explains

Thousands of excited fans flocked to a Thai zoo on Thursday to celebrate the first birthday of Moo Deng, the adorable baby pygmy hippo that has become a social media sensation. (AP video: Tian Macleod Ji)