At one time, the Little Blue Heron was a common wading bird in the Coastal Plain and Eastern Shore, but it has been in steep decline since the 1950s (from habitat loss?). Local birds leave our area after breeding to spend the winter in warmer climes. This duo may have arrived in Costa Rica a few weeks ago from the USA.
I am puzzled by the striking change from white in juveniles to blue plumage in adults. The color of other blue birds I know (e.g., Indigo Bunting shown recently) is created by refractive interference of light, not from pigment. Has the fine structure of barbules in feather vanes changed with age? Surprising if so. The adult shown here looks bright blue, although I’ve seen other images in which adults are purple-maroon on head and neck and dark slaty-blue on the back, so I’m not sure.