More than 30 lions rescued from circuses in Colombia and Peru are being flown to a sanctuary in South Africa.
The group organising the return, Animal Defenders International (ADI), says it is the largest airlift of lions.
The US-based group says almost all of the animals have been mutilated in captivity: some are declawed and have broken teeth, and one has lost an eye.
In South Africa, the lions will be released at the Emoya Big Cat Sanctuary, the organisers say.
“This is a hugely important rescue mission because it does make a statement around the world about the way people treat animals,” ADI spokeswoman Jan Creamer said.
The first group of nine lions was collected in Colombia’s capital Bogota on a cargo plane, which then flew to Peru’s capital Lima to pick up 24 more animals.
The plane is now heading to Johannesburg in South Africa, and is due to arrive on Saturday.
“It will be hugely satisfying to see these lions walking into the African Bush,” ADI Vice-President Tom Phillips was quoted as saying by the Associated Press news agency.
The lions were freed after the use of wild animals was banned in Peru in 2011 and Colombia in 2013.