Pigs don’t fly yet, but rhinos do.

Six black rhinoceroses were flown from South Africa to Zakouma National Park in Chad last week, reuniting the threatened animal with a land it has not roamed in nearly five decades.

Chad is one of several African countries that has recently sought to start its own small black rhino populations in an attempt to protect the species from extinction. It is a participant in the African Rhino Conservation Plan, which hopes to significantly grow the number of rhinos in Africa over the next five years.

“My fervent hope is that this reintroduction will contribute to the strengthening of conservation,” said Titus Matlakeng, South Africa’s ambassador to Chad.

Veterinarians in South Africa began training the six rhinos three months ago to prepare them for the trip, said Janine Raftopoulos, head of corporate communications for South African National Parks. The handlers kept the rhinos in bomas, or small enclosures, so they would be accustomed to spending time in confined spaces.

The rhinos were sedated for the flight and accompanied by support staff and veterinarians. They were closely monitored throughout the trip to Chad.

Up until the mid-20th century, black rhinos dominated the landscape of Chad, grazing and attracting tourists. But they also attracted poachers, who hunted them for their horns, which are coveted for traditional Chinese medicinal practices and are displayed as status symbols.

The population of black rhinos is down 97.6 percent since 1960. Some estimate that as few as 5,500 are left on the continent, according to the African Wildlife Foundation.

Cathy Dean, chief executive officer of Save the Rhino, an advocacy group, said six black rhinos were not significant in the context of the 5,000 or so that exist continentally. But it’s a good sign that Chad has a safe place to house rhinos now.

“That Zakouma National Park in Chad is considered sufficiently secure for a new rhino population is to be welcomed,” she said.

According to the African Wildlife Foundation, 98 percent of the current black rhino population exists in South Africa, Zimbabwe, Kenya and Namibia. South Africa, which is home to 40 percent of the rhinos, has already moved some of them to other countries, like Botswana.

Chad and South Africa have agreed “to share experiences and expertise in conservation matters and to assist each other on a reciprocal basis,” Mr. Matlakeng said in a speech last week, welcoming the rhinos to Chad.

Zakouma National Park will be responsible for protecting the rhinos from poachers and providing them with an adequate environment to live in.

Transporting the animals to create a new population is a plan that can prove effective, Ms. Dean said. “Some subspecies are performing really well, with an annual growth rate at 9 percent or even higher,” she said in an email.

But moving the rhinos to a place where they once were and no longer are isn’t enough. The population must be managed and protected, and law enforcement must play a role, Ms. Dean said. There should also be biological management, guided by effective monitoring. The rhinos cannot be dropped into a location and expected to mate.

The northern white rhino did not get the same opportunity to repopulate.

White rhinos and black rhinos are different species, and contrary to popular belief, both are gray. The species are very similar, but black rhinos have a pointed lip to help them pick fruit from trees, while white rhinos have a square lip that helps them graze.

In March, the last male northern white rhino, named Sudan, died in Kenya. Only two northern white rhinos are left in existence: Sudan’s daughter Najin and his granddaughter Fatu. Both are at the Ol Pejeta Conservancy in Kenya.

This is the kind of decline Mr. Matlakeng hopes to avoid in the case of the black rhino.

“Working together as a continent, we should continue to strive towards overcoming the plight of extinction of our iconic species, that define our common heritage,” he said.