[Photo] Keepers thought the colony was made up of 15 female bats.

A colony of fruit bats at a wildlife park in Essex surprised their keepers with some unexpected deliveries.

Staff at the Tropical Wings park in South Woodham Ferrers, near Chelmsford, thought their Egyptian fruit bat colony was made up entirely of females.

But the theory was blown apart in late January when eight of the 15 bats produced babies.

The park's head of mammals, Fiona Martin, said the arrival of the young bats was a "complete surprise."

Staff said the babies, who cling to their mothers for about six weeks before flying at three months, will be 8in long when fully grown.

She added: "Males and females are notoriously difficult to tell apart but now it seems we will need to take a closer look."