Ugandan authorities are hunting for a leopard in Queen Elizabeth National park after it snatched and ate a ranger's three-year-old son.

The toddler had been left in the care of a nanny at the unfenced staff quarters of a safari lodge in the park, when he was taken by the leopard on Friday night.

Wildlife authority spokesman Bashir Hangi said the child had followed the nanny outdoors.

"The maid was not aware the child followed her. She heard the kid scream for help, she intervened but it was too late the leopard had vanished with it in the bush and a search was mounted until we got the skull the next day," he said.

"The hunt is on with the intention of capturing the leopard and removing it from the wild because once it has eaten human flesh, the temptations are high to eat another human being, it becomes dangerous," he added.