11. Elephants without Borders

Botswana's elephants are doing very well, too well perhaps. People are worried that too many elephants will damage their fragile desert home and have suggested that up to 60,000 should be culled. Researcher Mike Chase studies ancient elephant migration routes - he has tracked them across vast deserts, desolate salt pans, and Angolan minefields. Now he thinks he has a plan that could safeguard their future.