This is a grey heron at St. James’s Park in London. How do I know it’s a grey heron, not a great blue heron? Because it’s in London. If it were in North America, it would be a great blue heron. There are undoubtedly other ways to tell them apart, but that’s probably the easiest.
BY THE WAY: This picture is a good example of my old camera vs. the new one. I took this at full zoom, and it’s a little soft. With the new camera, it would have been pin sharp.