Otto: A bird you don’t know – or do you?
I don’t remember exactly when I learned to identify the American robin.
I’m thinking it was probably about the same time I learned the northern cardinal (aka “redbird”) and the blue jay, but before the common nighthawk, which I clearly remember my dad pointing out one summer evening in 1969 as they soared above the playground at Longfellow School in Wheaton.
I’d imagine other folks have had similar experiences. Well, at least as far as robins, cardinals and the like are concerned. Because these birds are abundant in our area, we – even those of us who are not avid birders – become familiar with them early in life.
But every once in a while, even these well-recognized species can trip us up.
The other day, I received an email from Kent Gallagher of Geneva describing a bird with the exact coloration of an American robin. Well, exact coloration for every part except one.
Kent’s robin had an almost completely white head.
Yep, white. Not bald – bald would indicate the bird had parasites or some other condition that caused its feathers to fall out, and that’s a different topic altogether.
Kent’s bird displayed what is referred to as aberrant coloration – genetic blips that cause pigments to appear in lesser or greater quantities than normal. In this particular case, most of the feathers on the robin’s head, as well as assorted spots along its back, lacked melanin, a pigment that produces dark brown or black coloration in all manner of living things, plants and animals alike. (Although, curiously enough, apparently not in spiders. Again, a different topic altogether.)
Depending on with whom you’re speaking – an ornithologist, an aviculturist or a birding enthusiast – a bird with this condition also may be referred to as partially leucistic, partially amelanistic, pied, piebald or a partial albino – a term bird authority David Allen Sibley advocates as OK for use by birders in the field.
Although I wouldn’t say birds with partially white plumage are common in our area, they’re also not unheard of. In the past couple of years or so, I’ve heard from three other individuals who have spotted birds with aberrant plumages. Of these, two were robins and the other likely was a sparrow or finch.
Could those robins be the same one that Kent observed? Or possibly related?
I suppose they might be, but without actually capturing the birds and performing a genetic analysis, it’s impossible to say.
What we do know about birds, or any animals, with aberrant coloration is they face additional challenges in their daily campaign for survival. A patch of bright white feathers contrasts mightily with other normal-colored feathers, making camouflage difficult. Because plumage color often plays an important role in courtship, birds with abnormal pigmentation may have trouble finding a mate. And because melanin also contributes to feather structure, birds lacking the pigment may have feathers that are brittle, don’t protect from the elements very well, and can even break in flight – troubling consequences that often lead to shorter life expectancies.
As for Kent’s bird, we can make at least a couple of assumptions. Because the speckled-breast coloration of a juvenile robin has given way to the robin-redbreast plumage of an adult, and its beak is yellow, we know the bird is an adult and has survived anywhere from a few months to more than a year despite its white head and spotted back.
With fall migration in full swing, many thousands of birds are moving around and through our area each day. With the arrival of each new group, there’s always a chance that something unusual may pop up. Who can say? You may see a bird you don’t know.
Or do you?
• • •
If you’re the sort of person who finds natural phenomena endlessly fascinating, have we got a deal for you! After a year’s hiatus to retool and update, the Kane County Certified Naturalist program will return in January. The new KCCN offers six weeks of Tuesday night lectures along with three Saturday field trips geared toward specific areas of our local environment – geology and soil; weather and climate; ecology; woodlands and prairies; wetlands and aquatic systems; and zoology.
Details will be discussed at an information session from 7 to 8 p.m. Tuesday at the Hickory Knolls Discovery Center, located within the James O. Breen Community Park in St. Charles. Think you might want to attend? Give a call to let us know you’re coming, at 630-513-4399.
• Pam Otto is the manager of nature programs and interpretive services for the St. Charles Park District. She can be reached at 630-513-4646.