It's usually either your ATV or your camera drone, especially if it's daytime. That location looks like it might be around Bravo/Barbel, just past the radio tower on the West side of the canal. If I'm wrong, then it might be the top of the radio tower.
Viewing post in "Voices Of The Void" Pre-Alpha comments
Yeah that's weird. If you're a ways into the game (by days), then it could be a specific ent triggered by an event, but usually that one chases you. The other one that hangs around the NW quadrant only comes out at night, and doesn't usually get too close to the base. There are other triggered events too, and some of those may show up. If you don't see anything on the ground or in the sky, and you can eliminate the atv and drone, then tbh I dunno what it is.