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Twenty-First Century Birdwatching

Our ancestors!$ ^{(B)} !$ could spot natural predators from far by their silhouettes. Are we equally aware of the predators!$ ^{(A)} !$ in the present-day? Drones are remote-controlled planes!$ ^{(D)} !$ that can be used for anything from surveillance, to rescue operations and scientific research. Most drones are used today by military powers for remote-controlled surveillance and attack, and their numbers are growing. The Federal Aviation Administration (FAA) predicted in 2012 that within 20 years there could be as many as 30.000 drones flying over U.S. Soil alone. As robotic birds!$ ^{(C)} !$ will become commonplace in the near future, we should be prepared to identify them.

(Adapted from https://medium.com/looking-up/21st-century-birdwatching)