John Hume is the world's most successful private rhino breeder. But the burly South African farmer now fears his vast herd of endangered animals could be culled if he does not find the funds he needs to keep his ranch open.

Last week, the retired businessman wrote to MacKensie Bezos - the wife of Amazon founder Jeff Bezos - to ask for cash as he has run out of money to continue caring for his herd of over 1,500 animals.

“Her husband is the richest man in the world and when she is divorced she will have plenty, and she seems to be a decent person. Maybe she will help save our rhino," said Mr Hume, 77.

After a successful career running a holiday time-share business, Mr Hume retired to the Bushveld of South Africa in 1992 where he purchased the 20,000-acre Buffalo Dream Ranch estate.

Starting with just the two rhinos that came with the land, Mr Hume began breeding the animal. “They were the wildlife underdogs and I fell for them,” he says.