The Khao Kheow Open Zoo was overrun with Moo Deng fans on the first of four days of activities marking the birthday of the adorable social media sensation.

Thousands of fans have flocked to a Thailand zoo to celebrate the first birthday of Moo Deng, the baby pygmy hippo that's become a social media sensation.

The first day of the celebration coincided with Asalha Puja, a public holiday in Thailand, and many fans gathered outside her enclosure to watch her eat a $3,000 (THB 100,000) tropical fruit platter arranged to resemble a birthday cake.