SPRINGHOUSE FARM JOURNAL
By: Heather Lovett
I will never forget the first time I saw an indigo bunting. It was Aug. 4, 1998 (I made a note in my journal), and I was walking along the road about a half mile from my house, probably brooding about the month-long drought we were experiencing. As I approached the top of the hill, my attention was drawn to a frantic "spit! spit! spit!" in the trees to my right, so I stopped to take a look.
There, on a bare branch in a patch of sunlight, was a little bird of the most exquisite, intense blue, the back and chest a brilliant turquoise and the head a deep, rich indigo. It was so beautiful it took my breath awaya perfect jewel of a bird less than 5 feet from where I was standing, desperately trying to keep me from getting any closer.
Since then, I’ve been to Cape May during the spring migration, where there were so many indigo buntings they were practically falling out of the trees, and where I learned (with the help of friends who are bird experts) to identify shy brown females, and immature males with their hesitant, unfinished songs. Of course it was exciting, but even that experience couldn’t match the thrill of my first sighting.
I’ve since learned that indigo buntings are actually rather common, but are secretive and skittish in their movements and therefore often overlooked. They favor abandoned fields, railroad and power line clearings, forest edges, and brushy roadside hedgerows, where the nondescript female mostly stays out of sight, fearful of leading predators to her well-hidden nest. The male is easier to spot because of his bright plumage, but only when out in the open with the light hitting him just so.
Male indigo buntings have specially adapted feathers that act like tiny prisms, diffusing the light and giving the illusion of brilliant iridescent blue. It’s a gorgeous effect, but since his feathers have no actual blue pigment, he appears all black at certain angles. Fortunately, he is a show-off during breeding season, and sings continuously from a high perch in order to attract a mate. The easiest way to find him is to follow the music.
His song is a high-pitched warble of paired, rising and falling notes, with many individual and regional variations. Bird books describe it as: "tsee tsee, tew tew, teer teer"; "swee swee, seet seet, saya saya, seeo seeo"; or, my favorite: "fire! fire! where? where? here! here!" To my ears, the song of the tribe up the hill from us sounds something like: "chirry chirry, cheery cheery, chorry chorry," trailing off in a jumbled trill.
Older males arrive first in the spring (early May in these parts) to establish their territories, and the females follow about two weeks later. After choosing their mates, the pairs will raise two and sometimes three broods over the summer. This may be why indigo buntings continue to sing well into August and beyond, after many other birds have quieted down.
The female is stuck with virtually all household dutiesbuilding the nest, incubating the eggs, feeding the nestlingsin exchange for vigorous defense of the nest. To be fair, the male does help with feeding once the young leave the nest, especially if the female is busy starting a second brood. He is not, however, always faithful to his mate. In fact, there seems to be a lot of hanky-panky among indigo buntings in general. Genetic testing has shown that 15 percent of the males keep up to four "wives," and 20 to 40 percent of the young are fathered by males outside a nesting pair’s territory. Maybe that’s what all the singing is about.
Another challenge for the beleaguered female is the constant threat of parasitic cowbirds, which frequently lay their eggs in indigo bunting nests. If she isn’t smart enough to bury the cowbird eggs with a new nest floor (an observed behavior), the indigo bunting female will end up having to incubate and feed the huge adoptees at the expense of her own young.
Food is mainly insects and spiders during breeding season, and seeds and berries the rest of the year. Neighbors of ours have reported occasional sightings at their feeder, but such behavior is rare for these shy little birds. They are reputed to like the seeds of grasses, thistle, goldenrod, and dandelion, as well as blackberries, raspberries, and small rosehips.
Raising a family is a whirlwind affair for indigo buntings. The female builds her nest in three to four days, incubates the eggs for about a week and a half, and sends the babies packing only 10 to 12 days after they hatch, on average. The fledglings stay nearby for a few weeks, begging food from their parents, but by then the mother is already thinking about her next brood. No empty nest syndrome in this family.
Some time between late August and early November, indigo buntings gather in large flocks in preparation for their fall migration. Using the stars as their guide, they travel by night and stop to rest and feed during the day. Their destination is anywhere from southern Florida to northern South America, and when they settle for the winter they remain in loose flocks of hundreds and sometimes thousands of birds. During this phase the males are almost indistinguishable from the females because they shed most of their bright blue feathers.
Indigo buntings have been instrumental in helping scientists understand how migrating birds navigate. Experiments conducted in the 1960s demonstrated that the birds find their way in the night sky by using a group of constellations within 35 degrees of the North Star. They are able to get their bearings even when some of the stars are covered by clouds, and only become confused when the entire sky is overcast.
I always feel a little sad when these beautiful birds head south in the fall. It marks the end of the summer for me, and I know their return is not guaranteed. There are hazards along the way, not the least of which is a constantly changing environment, thanks largely to human interference. Long-distance migration (up to 2,000 miles) takes strength and stamina, and indigo buntings also run the risk of being captured in Mexico, where I’m told they are popular cage birds. It’s sad to think that exquisite beauty can harm a creature as well as help it, for surely these precious roadside jewels deserve their freedom as much as we do.
Sources:
Stokes, Donald and Lillian. "Stokes Guide to Bird Behavior," Volume II. New York: Little Brown & Company, 1983.
Deinlein, Mary. "Indigo Bunting (Passerina cyanea), A Stellar Migrant." Breeding Bird Survey Information, Smithsonian Migratory Bird Center, 1997.