White-bellied munia (Lonchura leucogastra) 

The white-bellied munia (Lonchura leucogastra) is a species of estrildid finch.

The name mannikin is from Middle Dutch mannekijn 'little man'.
Lonchura the Ancient Greek lonkhē meaning "spear-head" or "lance" with oura meaning "tail".
From Ancient Greek λευκός (leukós, “white”) + gaster (“belly”).