I have a pair of these nesting in the back of our property. They generally do that to cool themselves off. I thought the one was doing it to "impress" his mate, but apparently it's a cooling factor. They also pee down their legs to kill bacteria and vomit if they feel threatened. They are probably nesting there.
Mine have never come close to our house though. I even put a dead opossum about 20 feet from the back deck in open field, and they never came for it. Too close was my guess, because they had no problems cleaning up the predators I had taken care of and placed at the back of our property.