When chickadees change their tune

Black-capped Chickadee

Black-capped Chickadees usually sound the same everywhere, but Dave Gammon explored little pockets of improvisation. Photo courtesy of U.S. Fish and Wildlife Service.

Published April 15, 2004, in the Wyoming Tribune Eagle, “Young chickadees may be changing age-old song.”

2014 Update: David Gammon is now an assistant professor at Elon University in North Carolina where he continues to research in these areas of interest: vocal mimicry in northern mockingbirds, bioacoustics (study of the sounds of organisms) and cultural evolution and social learning in animals.

By Barb Gorges

Black-capped chickadees were the stars of the storytelling at the Cheyenne-High Plains Audubon lecture last month.

Dave Gammon, a doctoral candidate in the biology department at Colorado State University, was the storyteller. As all graduate students do, Dave had had the opportunity to ask a question and investigate possible answers and was now ready to tell his story.

To begin with, in deference to his major professor’s expertise, he chose to study chickadees. While Dave observed a captive specimen in the lab, it proceeded to sing a variation on the standard “fee-bee” tune that they are known for.

Reading the literature regarding black-capped chickadees, Dave discovered a study that showed that all across the country, they have one song that sounds pretty much the same everywhere, except in certain pockets.

Dave discovered in Fort Collins the males have three songs (only males sing). Where others sing the standard fee-bee, these birds have added an introductory syllable for a second song Dave describes as “fa-fee-bee,” or sometimes a third, “chick-a-fee-bee.”

All up and down the Poudre River corridor, full of trees essential to chickadee habitat, the songs are similar, though there is a slight variation from northwest to southeast. However, out on the prairie, in isolated islands of trees in small towns and on ranches, chickadees have added additional introductory notes to the “fa-fee-bee” song.

A lone bird on a ranch near the Wyoming border, which Dave recorded and nicknamed Ivan, was singing half a dozen introductory notes. To some extent, Dave recorded something similar among the chickadees at Guernsey in eastern Wyoming. Why does this happen and how does it happen? These were the questions Dave set out to answer.

He employed about 50 volunteers, who helped capture songs with dish microphones, and the good will of more than 20 landowners. He was able to incorporate and replay samples of those songs for us in his PowerPoint presentation as well as depicting them graphically as sonograms—lines representing the pitch, depth and length of sounds.

In chickadee culture, Dave said, the males are the first to rise. They sing without much notice of other males until they realize the females are awake. Then they stop abruptly and get directly to the mating business. Later in the day singing is more a matter of declaring territorial boundaries.

Perhaps having a repertoire of more than one song type helps these chickadees communicate better. Many songbirds have more than one song and scientists seem to think it’s an advantage.

Dave tested to see if different songs were reserved for females, the males’ way of showing off, but could find no statistical evidence.

Perhaps defending males would match particular songs of aggressors or vice versa, sort of a “Your Mama” insult competition, escalating until fisticuffs—or at least wing beating occurred. But unlike other bird species, there was no significant statistical difference.

Perhaps, thought Dave, these changes in chickadee song are merely accidental, the result of young birds making mistakes and never being corrected Does humanizing that idea make parents responsible for the beginning of heavy metal music?

A chickadee nestling, Dave said, is born in a cavity of a tree, insulated from noise. During incubation and after hatching, he is unlikely to hear his father sing near the nest because it would attract predators. After a few weeks, the youngster leaps from the nest, never to return and moves up to one or two kilometers away where he stays the rest of his life.

Normally, in prime chickadee habitat, where the woods stretch for miles, wherever the young chickadee lands, he will be surrounded by chickadee mentors. If he makes singing mistakes, and he will—Dave has recorded juveniles really jazzing things up—he’ll learn to conform.

But if any young chickadees ever disperse as far as old Ivan’s lonely place, they’ll probably wind up sounding much like him. What would their mothers think if they knew!

Apparently there are other pockets of subversive chickadee song in an example of convergent evolution: Martha’s Vineyard, Mass., Puget Sound, Wash., Fort Lupton, Colo., and Guernsey, Wyo. The only Cheyenne chickadees Dave found were mixed pairs of mountains and black-caps—another interesting conundrum.

And then one of the audience members, visiting from Casper, thought maybe her backyard chickadees might also sing “fa-fee-bee.” Dave’s eyes lit up.

The new questions are: How widespread is this phenomenon? How long ago did these breaks from the standard “fee-bee” occur? Will a multiple song repertoire eventually prove to be advantageous to chickadee survival and population growth? What new variations will this year’s hatchlings come up with?

Dave would like to squeeze in one more chickadee field season. We hope wherever he lands his first job after earning his degree, it’s in black-capped chickadee habitat.