This white bird in a far-away tree had us puzzled for a while.
Adult male Eastern Bluebird
Male Eastern Bluebird with white necklace
Juv Eastern Bluebird, limited partial leucistic
Leucistic Eastern Bluebird, left profile
Leucistic Eastern Bluebird, right profile
Leucistic Eastern Bluebird, flying, showing uneven dark feathers
Leucistic Boat-tailed Grackle, Rodman Dam
Partially leucistic American Goldfinch, with white feathers on the back
“There goes that white bird again.” This became a common refrain as we began seeing it here, there and everywhere around our property. But it would never let us get very close to it, as it was wary and quite skittish.
This is probably a good thing, for a white bird stands out as an open invitation to predators looking for their morning meal. Seen from 200 yards away, the white bird is highly conspicuous, unlike virtually all other small birds which are able to blend in and adapt to their surroundings. While movie stars, prancing on the red carpet heading into the Oscar ceremony want to stand out and don ever more attention grabbing garb to be sure they are seen, birds rely on their coloring to shun attention and avoid catastrophe.
Of course, as with any rule, mating season provides the exception, when birds, as well as humans, try to look their absolute best. But pure white is not what either chooses, for even white birds, such as herons and egrets, while keeping their white feathers, temporarily change the color of their beaks, legs, feet, or eyes to make themselves stand out. And white wearing humans are probably heading for an altar.
For several days we closely followed our white friend’s travels, noting favorite perches and hunting areas. It became clear that a certain cluster of trees were favorites, but not the Bird Tree, where I had waited so patiently for it earlier. After setting up my blind at what I now knew was a favorite hunting tree, I discovered that “Whitey” had several traveling companions. First, there was almost always a male Eastern Bluebird; second, a regular companion, also an obvious Eastern Bluebird, wore a white necklace, and had white flecks on its wings, neck and face; a third fellow traveler had an even whiter necklace, throat, face and head, but the obvious reddish breast and blue tail feathers of another Eastern Bluebird.
But when “Whitey” flew onto what I now knew was a favorite perch, the white plumage and bright yellow bill, legs and feet were stunning. From his left profile, only a very light tinge of color across the top of his head provided any color whatsoever, except for the very dark eyes. But when he flew down to capture a bug and returned to the tree, his right profile was not as pristine white.
A dark smudge on the face, in front of the eye, and a dark spot on his upper mandible were quite prominent. In addition, there was apparently some coloring on the back. But it was pretty clear that he was also an Eastern Bluebird, and a fair conclusion could be drawn that the three bluebirds with varying amounts of white were probably from the same nest: hence, an unusual brood. (I have used the masculine in referring to “Whitey,” but don’t really know whether that is correct.) When he flew into another cedar tree he displayed an asymmetrical color pattern on his back and wings, which along with the dark eye, clearly distinguished him from a true albino.
Birds with white feathers where there should be colored feathers are called “leucistic.” Birds that are “fully leucistic” have virtually no coloring in their feathers whatsoever. Birds with some white feathers, but also with some colored feathers are “partially leucistic,” which can vary from only a few scattered white feathers, as in two of this “uncommon brood,” to almost completely white, as in “Whitey.” The condition is caused by the partial failure of the bird to produce melanin, the color in the feathers, and can vary greatly.
True albinos have absolutely no colored feathers and have pink eyes which results from a complete failure to produce any melanin whatsoever. This genetic condition, which affects pigment in skin and eyes as well as feathers, can occur at times in all vertebrates, including humans, although it is very rare. More research is still needed to determine whether leucistic birds replace, lose, or gain more of, their white feathers with each successive molt.
In addition, a male American Goldfinch with only a few leucistic feathers on his back, feasted on our cone flower seed pods recently. We are sure he was not a nest mate of the bluebird brood, but he did make us wonder whether there is something in the water around here. This unusual brood reminded us of the leucistic Boat-tailed Grackle we observed at the Rodman Dam on the Ocklawaha River in north/central Florida several years ago. That poor fellow also had a deformed claw to contend with, as well as the mating disadvantage of an inability to puff up shimmering iridescent blue/black feathers to impress the girls.
Leucistic birds are unique and provide a fun diversion from regular birding. It will be interesting to follow “Whitey” to see what the future holds for him, assuming he survives. Who knows, his very different plumage may just prove attractive to a prospective mate. Could be next year’s unusual brood; or maybe an avian “Rosemary’s Baby?” We will just have to wait to see.(10/23/14)
For more on leucistic birds, see: http://birding.about.com/od/identifyingbirds/a/leucism.htm and http://www.sibleyguides.com/2011/08/abnormal-coloration-in-birds-melanin-reduction/. For fascinating photos, (not mine) of an albino Ruby-throated Hummingbird, see http://www.naturefriendmagazine.com/photos/?catid=9
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