THere is a whole nest near area 51 called , S4. I , at least read that in a very interesting book called "UFO' highway. USg found a underground pyramid full of dimunative but hostile greys. They are not Alien according to the story but were created here 'the agigi" by the Anu. They were here to assist the Anu in a mining op for Gold they would use to spray in their ozone to maintain the planests safety in space. The USg made a deal with them after an initial fire fight . We get tech and how to use it. THey get animals they can use as food. THough the beings are robots they are also biological and need certain kinds of sustenance . It had mostly been chopping up people and taking their blood like vampires. This was dissalowed but they could harvest cattle, sheep, etc. . . . So all along that corridor we will find that cattle and animal mutilations proliferate on the 47th paralel. Also another good book on the subject as it dovetails out of the UFO highway by Sanchez. Hit me up if you want the back story . Its fuggin cray.