Because someone got out of a car and scared them with a camera.
ETA: Initially, I thought these might be wild turkeys. I spent some time last night googling photos of turkeys and different birds and couldn't find any like these since I didn't know what they were. I asked Mr. Backwoods and he glanced at them and said, "Yes, they're turkeys." So I posted them; then someone tells me, nope, they're guineas. After googling again to confirm I showed the pics to Mr. Backwoods again and he says, "Oh, no those aren't turkeys. I wasn't really paying attention." Gee thanks, Hon.