How do birds choose the perches they use? Several times last month I saw a female Belted Kingfisher (Megaceryle alcyon) perched in the early morning on this monitoring equipment sticking out of the water. Somehow I had the impression that the kingfisher was spending the nights on that perch.
Perhaps it’s more comfortable (or maybe safer) than the surrounding trees. Whatever the case, it makes for an interesting juxtaposition of natural and man-made elements in the image.
© Michael Q. Powell. All rights reserved.
Mike Powell 
We have a hawk that does the same thing with light poles. I assumed it was for height, but maybe not.
For the hawk, that might be the case. For the kingfisher, the perch was only 3 or 4 feet above the water, so height might not be the biggest reason. Other have speculated the equipment gives off a little heat and warms the feet. Who knows?