In addition to meeting whatever requirements the Federal Aviation Administration may have in place for such projects, Amazon Prime Air drones may also have to face actual physical threats. Assuming the company will be allowed to use unmanned autonomous flying devices to deliver goods in 30 minutes or less, Amazon will need to figure out a way to help its drones avoid bird attacks and even sniper threats. Slate mentions a variety of examples from the wild, in which various species of birds attack other birds or flying devices perceived as potential dangers to their habitat.

“Open-country raptors – hawks, eagles, kites, harriers, etc – don’t take kindly to interlopers on their hunting grounds, and frequently chase, dive-bomb and take talons to intruders,” bird specialist Nicholas Lund writes. “The confrontations can be even more violent during nesting season when vulnerable chicks are potential prey.”

Lund also added that there were various instances in which flying devices were attacked by birds (see video below) and reminded us that the FAA has tracked more than 121,000 instances of bird-aircraft collisions since 1990.

The current design of Amazon Prime Air drones may make them vulnerable to other kind of threats as well, such as snipers shooting at them from the ground. Washington Post reporter Brad Plumer half-jokingly tweeted that good shots may have a chance of scoring free stuff from Amazon if they can shoot off the vehicles’ propellers.

A new Bloomberg story similarly says that Amazon’s drones “could be sitting ducks” thanks to their current design. The device has eight exposed propellers that may be harmed when attacked from the ground in the manner described by Plumer. Amazon’s CEO Jeff Bezos said that the drones can fly even when a propeller is damaged, although he didn’t mention the minimum number of working propellers required to keep the drone in the air.