Drones are flying to the defence of tortoises in the USA's Mojave Desert. Tortoises in the Mojave are under threat of being wiped out by ravens. The raven is a bigger version of the crow. The raven population in the Mojave has increased by 700 per cent in the past 25 years. This has had a catastrophic impact on the desert tortoises. A local conservationist said that in some places, "where there used to be 10 ravens, there are now 15,000". If nothing is done to help the tortoises, they could be completely wiped out. Their numbers have fallen by over 90 per cent since 1990.
Technology may rescue the tortoises. Biologists and drone operators have a strategy to reduce the raven population. They are using drones with a technique called "egg oiling". This involves flying drones up to ravens' nests, removing fertilized eggs, coating them with corn oil, and then replacing them. The oil blocks oxygen from entering the egg, thus ending the life of the embryo inside. A biologist said: "If ravens figure out that their eggs are rotten, they are likely to...nest someplace else." A conservationist said egg oiling was justified as "part of a comprehensive approach".