Conservationists in South Africa are marking World Rhino Day on Monday under the shadow of poaching.

The country is home to most of the world’s black and white rhinos, but that also makes it the epicentre of the battle to protect them.

The Dinokeng Game Reserve in South Africa has a thriving rhino population, but their exact numbers and the details of the security operation that keeps them safe from poaching are closely guarded secrets.

They are the basic protocols that reserves with rhinos follow to ensure they are not the next target for poachers who still kill on average one rhino every day in South Africa.

Marius Fuls, a wildlife monitor at Dinokeng Game Reserve, says he's undeterred.

"If we as conservationists stop believing that we're going to win this, then we have lost it. We're the last thin green line between the extinction of rhinos," he says.

South Africa has the biggest populations of both black and white rhinos in the world and sees itself as the “custodian” of the animals' future, according to Environment Minister Dion George.

White rhinos, the larger of the two species, graze in savannahs and grasslands.

Black rhinos tend to prefer denser bush and shrubs.

According to the International Rhino Foundation (IRF) the total global population of rhinos is approximately 26,700.

In South Africa conservation groups estimate only around 2,000 black rhinos remain with around 12,000 - 13,000 white rhinos.

That means the country has a pivotal place in saving the species but also means it is the epicentre of rhino poaching that conservationists say is increasingly being carried out by organised criminal syndicates.

Gillian Rhodes from the Peace Parks Foundation says the crisis has been contained since its peak a decade ago.

“In 2014 at the height of the crisis, we were losing, I think in excess of 1,400 rhinos a year for several years, I think it's quite phenomenal that a decade later despite intensive pressure, like that we really have managed to suppress and hold back the problem," she says, conceding that some areas still require a lot of strengthening.

Conservationists say protecting rhinos remains a long struggle but hope remains in community engagement, international support and continued vigilance - as the world marks World Rhino Day on 22 September.

AP video by Alfonso Nqunjana