Juvenile Little Blue Heron.

The article discusses that comparison shows there really is no such thing as an unmistakable bird. English names for birds are often imprecise. Consider the terms heron and egret. We use them as if they mean something different, but the difference between herons and egrets is arbitrary. For example, Little Blue Heron and Snowy Egret are members of the same genus: Egretta. Apparently close relatives, they can be surprisingly hard to tell apart.