The animals flown into the Matusadona National Park over the past week were descendants of black rhino removed in the 1990s as poachers slashed their numbers, the park manager said.

"It's their descendants that we're bringing back into the system," Michael Pelham told AFP, adding the project was believed to be the first of its kind on the continent.

"We are rewilding with our own genetics coming back," he said.

Over one year in the early 1990s, poachers after rhino horn dropped Matusadona's rhino population from an estimated 250 animals to just 16, he said.

A nine-year poaching spree across Matusadona and other parts of the northern Zambezi Valley cut the area's black rhino from 3,500 to just 400 animals, he said.

"In this situation, it was feared we would possibly lose all of the genetic stock, so surviving animals were moved," Pelham said.

Most went to other parts of Zimbabwe but about 25 were shipped to Australia and Texas.

"Some of the animals that we took out of Matusadona in the early 1990s are still alive, but too old to bring back here and move again," Pelham said. "But their offspring are coming back into the park."

The new arrivals were dehorned and new technology such as drones and trackers was in place to safeguard them against poaching, he said. Another 20 were due to arrive next year.

The world's black rhino population dropped from approximately 65,000 animals in 1970 to only 2,300 in the wild in the early 1990s, according to the International Rhino Foundation.

The numbers had recovered to about 6,800 after intense anti-poaching efforts, it said.