High-tech drones are flying to the defence  tortoises in California's Mojave Desert. The desert tortoises  the western Mojave are  threat of being wiped out  ravens. The raven is a larger version  the crow. Its population in the Mojave has increased  more than 700 per cent in the past 25 years and this is having a catastrophic impact  the desert tortoises. Allison Fedrick, a local conservationist, observed that  some places, "where there used to be 10 ravens, there are now 15,000". Ms Fedrick noted that if nothing was done to help the tortoises, they would be completely wiped . Their numbers have plummeted  more than 90 per cent since 1990.
Technology is coming to the rescue  the tortoises. A team  biologists and drone operators has come  with a strategy to reduce the raven population. They are using drones and the use  the method of "egg oiling". This involves flying drones  to the ravens' nests, removing fertilized eggs, coating them  a film of corn oil, and then replacing them. The oil blocks oxygen  entering the egg, effectively ending the life  the embryo inside. Biologist Mercy Vaughn said: "If ravens figure  that their eggs are rotten, they are likely to eat them and nest someplace else." Conservationist John Griffin said oiling was justified as "part  a comprehensive approach that...addresses all other factors".