Mystery drone squadrons flying over Colorado and Nebraska

For the last couple weeks, residents of Colorado and Nebraska have reported squadrons of large drones flying overhead. The drones are large, with a reported 6-foot wingspan, and their operators and purpose remain a mystery. The Federal Aviation Administration has now opened an investigation into the matter. From the New York Times:

Some have suggested they might be part of a simple mapping operation, or a land survey conducted by an oil and gas company - but why would such flights run at night?...

The drone sightings started in northeast Colorado around mid-December and have only grown more widespread since then. Almost all the sightings have occurred between sunset and about 10 p.m., though (Palisade, Nebraska resident Missy) Blackman said she had seen them out later one night in Nebraska and, for the first time on Wednesday, during daylight hours. She said she had looked at them through binoculars and did not see any markings, just plain silver and white coloring.

Across the state line in Colorado, Captain Yowell tried to photograph the drones on Tuesday night with the camera he uses to document crime scenes, but came away without a clear image. He estimated that up to 30 drones were flying each night, though not all in the same place...

Sheriff Todd Combs of Yuma County, Colo., said in a Facebook post Tuesday that the drones appeared to be staying at least 150 feet from buildings or people, based on the footage he has seen.

"There are many theories about what is going on, but at this point, that's all they are," he said. "I think we are all feeling a little bit vulnerable due to the intrusion of our privacy that we enjoy in our rural community, but I don't have a solution."

"'It's Creepy': Unexplained Drones Are Swarming by Night Over Colorado" (NYT)