I've seen these birds only a few times. They are huge. The first time I saw one, I was driving in my truck, and the big, blue bird had its neck extended. By my estimation, the top of its head probably made the bird as tall as me!
I saw this one in my yard when I opened the back door to let the dogs out one morning this week. It's head was up and stayed up until it saw the dogs, then it scrunched its head down and froze. I grabbed my camera and stuck my head out the back door just in time to snap this shot. Once the dogs headed out front and away, the bird took off. With the bird close to 200 feet away and my camera zoomed to the max, I wasn't able to find the bird in the viewfinder as it flew off. The wingspan looked to be about 10 feet!