CHONBURI, Thailand — 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.

The world's most famous one-year-old female pygmy hippopotamus, Moo Deng, enjoys a cake made of various fruits and plants to celebrate her first birthday at Khao Kheow Open Zoo in Chonburi province, ...