And that small white bird was a Little Blue Heron. You might be wondering why a "Little Blue Heron" is white, and this is because it is a juvenile Little Blue Heron. This species begins life in all-white plumage and individuals transition to their deep blue plumage upon maturity.
I would like to take a moment to talk a bit about the name "heron." As you might know, there are herons and egrets; both look essentially the same, aside from species-level color differences. You might be thinking there is some kind of difference between the two groups, like there's something that makes a heron a heron, and an egret an egret. I definitely thought that until I started my research for this post. Turns out, there is no significance to the names. Although the Little Blue Heron is called a heron, that name doesn't mean much in itself; in fact, the Little Blue Heron is most closely related to the Snowy Egret. So why the two groups of names? It's basically due to linguistic and societal differences. Birds in the family Ardeidae are called the herons. The name "heron," when talking about etymology (the study of a word's origin and history), comes from certain Germanic languages including Middle English. Egret, on the other hand, is still Germanic, but is based on the Old French word "aigrette," which is pronounced "egret." Aigrette can translate to "little white heron," but also refers to long, decorative plumes that certain heron species grow during breeding season. So basically, the French term "aigrette" was borrowed by English and morphed into "egret." This term was then applied to white herons, many of which also have those decorative plumes during their breeding season. However, when you look at the evolutionary history for these long-legged waders, you see that there's no biological basis for the differences in names; the birds we call egrets and the ones we call herons are all intermixed in various genera, and they don't break down into two completely separate groups. This is one of the many reasons why common names can be deceiving!
In the end, natural selection selects for white-plumaged juveniles and dark-colored adults. By having this dimorphic coloration system, the Little Blue Heron optimizes survival across its entire life cycle from nestling to breeding adult.
That's it for this post! Thanks for reading!