Four warty pigs have been born at a British zoo.

This is the second litter for their mum Polly whose first was in December 2015.

They have just spent their first day in their outside paddock at Bristol Zoo and have stayed close to mum Polly.

If she strays too far from them they will call out to her.

Sarah Gedman, mammals team leader, said: "The piglets are striped for camouflage at this age as they would be vulnerable to predators in the wild.

"The stripes will fade with time until they turn into perfect miniatures of their parents."

Keepers at the 180-year-old zoo do not know the sex of the piglets as they are staying close to their mum so none has yet been given a name.

The Visayan warty pigs are endemic to two of the Visayan Islands in the central Philippines.

The species is classed as Critically Endangered by the International Union for Conservation of Nature on its Red List, due to loss of habitat, food shortages and hunting.

In the wild, there are two separate remaining populations of warty pigs - on the islands of Panay and Negros.

The latter of the two islands is also home to an in-situ bleeding heart dove conservation programme, which the zoo co-ordinates.

The species is being managed to provide a self-sustaining captive population and to develop important care and breeding techniques for use in the Philippines.

Visayan warty pigs share characteristics typical in wild pigs; they possess medium-sized barrel-shaped bodies and short legs.

Despite their name, the Visayan warty pigs have only small facial warts.