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fly be be be increase have observe note wipe plummet
come come reduce use involve replace end figure nest address
High-tech drones are to the defence of tortoises in California's Mojave Desert. The desert tortoises in the western Mojave under threat of wiped out by ravens. The raven a larger version of the crow. Its population in the Mojave has by more than 700 per cent in the past 25 years and this is a catastrophic impact on the desert tortoises. Allison Fedrick, a local conservationist, that in some places, "where there used to be 10 ravens, there are now 15,000". Ms Fedrick that if nothing was done to help the tortoises, they would be completely out. Their numbers have by more than 90 per cent since 1990.

Technology is to the rescue of the tortoises. A team of biologists and drone operators has up with a strategy to the raven population. They are drones and the use of the method of "egg oiling". This flying drones up to the ravens' nests, removing fertilized eggs, coating them with a film of corn oil, and then them. The oil blocks oxygen from entering the egg, effectively the life of the embryo inside. Biologist Mercy Vaughn said: "If ravens out that their eggs are rotten, they are likely to eat them and someplace else." Conservationist John Griffin said oiling was justified as "part of a comprehensive approach that... all other factors".

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