It's tough enough to come up with the correct ID for the varied finches that gang up around my feeder every day, so when you have a leucistic one show up, the whole day gets disrupted. My pal Brent McGregor happened to run into one in his backyard the other day.
The first thing that usually happens when a white, speckled bird arrives (one that you know shouldn't be devoid of coloration) is that someone calls it an albino. Wrong. An albino is always pure white and devoid of any coloration—even the eyes, which are always pink to red, as in "blood red." "Albinism" is just that, no coloration, even the eyes.
All the others with weirdo coloration are leucistic. The usual lack of coloring in plumage of leucistic birds is combined with little splashes of what the bird looks like in normal plumage, and—if one looks carefully—has (normal) dark eyes, not blood red or pink. That's a bird with screwed up genes which has lost the ability to carry the normal coloring onto the next generation.
Leucism is the term for the type of patchy coloring resulting from defects in genes that control color cells of skin, hair, or feathers. This results in either the entire surface (if all pigment cells fail to develop) or patches of body surface (if only a few are defective) having a lack of cells capable of making normal color—but not the eyes.
Therefore, the noticeable difference between albinism and leucism is in eye color. Due to the lack of melanin production in both the retina and iris, those affected by albinism typically have red eyes due to the underlying blood vessels showing in the cells.
(Melanin, in case you're wondering, is any of the various black, dark brown, reddish-brown, or yellow pigments of animal or plant structures—as skin, feathers or hair. Melanin is the root of what gives color to skin, hair, eyes, and plants, ubiquitous in every entity on Planet Earth that has a hue/color.)
This is a wonderful time of the year to go birding, looking for that unusual plumage. A leucistic bird stands out like a sore thumb—especially a Mexican Jay; they really stand out!
Every once in a while, a non-U.S. species gets blown off course so badly in winter that they end up in our western flyway, bewildered, not knowing where they are, or what to eat.
I can recall that happening while I was with a bunch of wildlife biologists who were on a Bureau of Land Management tour out on the high desert, looking at playas modified for water storage for cows. (Several of the biologists thought a better term for the modification was "destroyed.")
We were at a huge modified playa south of Brothers on the Great Sandy Desert. As we dismounted from our pickups we could see a rather large group of black and white waterbirds scuttling along on the surface to avoid us. I thought they looked like ocean birds—Surf scoters to be exact—but I didn't say so—and neither did anyone else—until a more daring U.S. Fish and Wildlife biologist said, "Say, aren't those Surf scoters...?" Then everyone jumped in, "Yeah, they sure look like it." Through some act of weather, they were blown away from the Pacific Ocean and ended up on the playa—perhaps thinking, "water is water," but wondering why it tasted so funny.
Therefore, if you see a bird in your backyard that you either don't know, or looks like something you saw in a Japanese bird book, first, do your utmost to get a photo. Then get in touch with a birder's hotline.
Over my long and wonderfully happy years of birding I have seen some beautiful strangers who have flown off course, making it to the local park or my backyard. Among them have been a wonderful variety of leucistic robins, swallows, red-tailed hawks and infernal finches I can never identify.
(Finches, for me, are "LBJs, aka Little Brown Jobbies." I had to ask our Oregon Master Birder, Tom Crabtree of Bend, if the photo Brent sent me was really a house finch. All the finches that come to our feeder are "LBJs or house sparrows," but occasionally my wife, Sue, will try to show me how to accurately identify them. My response to that is usually, "Duuuuuugh.")
Now I have a favor to ask: In the midst of your busy life, try taking the time to get out with your kids looking for leucistic/albino/wintertime strangers around your home. If you see a strange bird suddenly appear on your feeder or near the woodshed, try to get a voucher photo and send it to me. We'll all have a great time ending the year 2016 wondering who and what has dropped in, and what the year 2017 will bring us.
And if you're wondering what 2017 will be like, you're not alone.