When you get the viral blues, when you think you are actually living “Ground Hog Day” every morning when the alarm goes off, just when the lockdown has you at the end of your rope, you can really benefit, as I did, from the artwork of a 5 year-old. She knew I was a “bird person” and possibly sensed my blues, so she sent me “Bluebird at Night”. It worked. The blog is back.
We have four relatively common birds that share the striking blue plumage, but all with slightly differing hues: the Indigo Bunting, Blue Jay, Blue Grosbeak, and Eastern Bluebird. I have shared the physics of the blue coloration with you in prior posts, but it’s an interesting story and worth repeating.
The coloration of a bird’s feathers can be caused either by pigments, or the actual structure of the feather itself. Pigments are ingested by the bird and become part of the feathers. The depth of color reflects the amount of carotenoids, melanin, and other pigments in the diet and may indicate the health of the bird. The color we perceive is the reflected light from the visible spectrum of color; the other wavelengths are absorbed by the pigment molecule. The color reflected by pigments is not dependent on the position of the viewer.
There is no blue pigment for the birds. Any blue pigment that the bird eats is destroyed by the digestive process. Instead, their blueness is dependent upon a complex structure of layered keratin and air pockets within the feather that reflects the blue light in the spectrum. This structurally dependent color may vary with the positioning of the observer. The selective advantage for the intensity of the male’s color might reflect the preference of the female in choosing a healthy male, or may possibly just indicate her appreciation of his beauty.
Most birder’s remember the day they first saw the intense color of the Indigo Bunting, the bird most likely singing near the treetop at the edge of a wood. Oohs and ahhs, and a double check in the guidebook to confirm. For me it was a decade ago at the Corkscrew Swamp in Florida, at least as recorded in my eBird, however, in reality I think it was during childhood in Upstate New York. It’s a blue like none other; difficult to describe. The much drabber color of the female, as with other dimorphic birds, indicates that she does much of the clandestine nesting chores. It’s interesting to note that sexual dimorphism is much more prevalent among migrating birds such as the Indigo Bunting, whereas it is much less common among non-migrators.
The Blue Jay is an under appreciated beauty, perhaps due to its obnoxious loud call or aggressive behavior. The bird is also one of the smarter of the Aves. They often hide their food for later in the day or season. Some ornithologists claim that when a Blue Jay notices another bird watching him hide the food, he will return a few minutes later when the other bird is no longer watching, and move the cache to a safer place. That takes quite a bit of reasoning and brain power.
David Sibley, the famous birder and author, comments on the striking white and blue coloration and suggests that the bright, white flashes of the wings serve as a distraction to an attacking predator. He also says that the tuft and resultant shape of the jay’s head confuses the attacker who can’t figure out which way the jay is looking. These predators are not so bright. You can add the Scrub Jay, Steller’s Jay, and even the Eurasian Jay for the small patch of blue in its wing, to the collection, but these birds are not found in this neck of the woods.
The Blue Grosbeak is closely related to the jays and buntings. It also is a highly dimorphic migrator with the males displaying a pleasing mixture of blue and chestnut. It likes the fields and brushy habitats near water and is a rarity much further north than lower Pennsylvania. That accounts for me not noticing this bird until I left Upstate New York and moved to Maryland. It’s primarily a field bird and rarely visits our yard.
I saved the Eastern Bluebird for last. It also has a unique shade of blue as you all know. The bird is ubiquitous around here, probably the most common bird in the yard. What a comeback! The contrast of the orange breast, caused by pigments, with the structural blue is wonderful and unmistakable as the bird flashes by from bird house to bird bath and back again. The species is a dimorphic, short distance, migrator, but our winters have become so mild that the local birds grace us with their color all year long. I would be remiss in not mentioning for my Coloradan friend John, that the same vibrant blue occurs in his Mountain and Western Bluebirds as well.
So just remember, “It’s the truth, it’s actual, everything is satisfactual”. Mister Bluebird is on your shoulder. “Zip-a-dee-doo-dah, zip-a-dee-ay.” I hope you all have an Ember in your lives as a reminder that better days are just ahead.