Clint Eastwood and the Waxwings
In real time, the authors estimated 400-500 Bohemian waxwings in the tops of the trees behind the house. Later, counting from a photograph, they discovered there was more than a thousand. Courtesy of Jeff and Allison Wells.
A portion of the massive flock of waxwings in the authors' neighborhood. Vocalizing together, the birds sounded like a hissing teakettle. Courtesy of Jeff and Allison Wells. 
This Cooper's hawk just finished devouring a northern cardinal on the authors' porch. It's been hanging around the neighborhood throughout the winter. Courtesy of Jeff Wells.
In real time, the authors estimated 400-500 Bohemian waxwings in the tops of the trees behind the house. Later, counting from a photograph, they discovered there was more than a thousand. Courtesy of Jeff and Allison Wells.
A portion of the massive flock of waxwings in the authors' neighborhood. Vocalizing together, the birds sounded like a hissing teakettle. Courtesy of Jeff and Allison Wells.
This Cooper's hawk just finished devouring a northern cardinal on the authors' porch. It's been hanging around the neighborhood throughout the winter. Courtesy of Jeff Wells.
In the Clint Eastwood movie, “Pale Rider,” a group of independent gold prospectors live and pan for gold in a picturesque canyon rimmed with tall fir trees in northern California. The number of miners increases, and eventually some of the miners find gold, and this gets the attention of the wealthy owner of a large, industrial mining company operating upstream who uses his men to try to intimidate the prospectors to get them to give up their mining claims and leave.
Spoiler alert: Clint Eastwood’s dusty, leather-clad, tough, loner character shows up, beats up the bad guys, and dynamites their operations. The movie ends in classic Eastwood style, with his character cleverly taking out a bevy of scary, corrupt gunslingers all wearing distinctive long, western duster, tan trench coats.
What, you may ask, does this have to do with birds?
It’s a fair inquiry.
Consider, if you will, the question of flock size in Bohemian waxwings. We had the unusual circumstance of coming across a massive flock of the said species only a block from our house last week. The sound of this many Bohemian waxwings all calling from the tops of the bare ash and maple trees at the corner was like the sound of a whistling teapot.
It was impressive. We took photos and video and made some sound recordings because it was just so cool! Then we tried to figure out how many birds there were. Hundreds, certainly, we both agreed. But how many hundreds? We tried the standard procedure of counting a certain number and then extrapolating. At least 400 we estimated, perhaps closer to 500. And we submitted the record to eBird so that it will be included in this year’s Great Backyard Bird Count (which ran from Feb. 13-16).
Later that day, we printed out photos of the flocks that were arrayed in the treetops and studiously counted each and every bird. We were expecting that we had underestimated but we couldn’t believe by how much—there were 1040 birds there (probably a few more)!
That’s a lot of Bohemians!
We began pondering the question of why so many waxwings would show up in one place. We were pretty sure the reason they were in this particular spot at this time was to take advantage of the frozen crabapples on a neighbor’s tree. Over the course of several days previous to the arrival of the massive flock, we had seen a small flock of 20 or so birds there, then a flock of 120 or so the next day, followed a few days later by this massive mega-flock.
Somehow, other flocks of Bohemian waxwings had found out about the “goldmine” of crabapples in our neighborhood. Like the prospectors in Clint’s “Pale Rider” movie, they had congregated in a place that offered great chances of success (in the case of the waxwings, for a good meal).
But a thousand waxwings in one place is loud and noisy. We weren’t “bad guy” predators, but we had noticed the whistling teapot sound and came over to watch them just as the wealthy, corporate industrial mining magnate had noticed the prospectors in “Pale RIder.” From the waxwing’s perspective, the equivalent was the hungry, bird-eating Cooper’s hawk that lives in our neighborhood. The large flock must have made them more conspicuous and a target for attack by that bird.
In our story, the birds have to figure out whether to stay in the big conspicuous flock or spin off smaller flocks to look for another fruit tree away from the others. Scientists who study animal groups describe the changing of group size and composition under different conditions as fission-fusion dynamics. Larger groups can benefit from the ability to find and exploit new food sources, spot predators, gain thermodynamic advantages, and experience other advantages. But form too large a group and some of the members may lose in the competition for food—or they may be more visible and become food themselves for predators, with no tough Clint Eastwood character to protect them!
Watch a short video clip of the massive flock of Bohemian waxwings in the authors' neighborhood - listen closely to hear the "hissing teakettle" sound of the birds' vocalizing. Courtesy of Jeff Wells. https://youtu.be/_MhK84ri2PY
Jeffrey V. Wells, Ph.D., is a Fellow of the Cornell Lab of Ornithology and Vice President of Boreal Conservation for National Audubon. Dr. Wells is one of the nation's leading bird experts and conservation biologists. He is a coauthor of the seminal “Birds of Maine” book and author of the “Birder’s Conservation Handbook.” His grandfather, the late John Chase, was a columnist for the Boothbay Register for many years. Allison Childs Wells, formerly of the Cornell Lab of Ornithology, is Senior Director of Communications at the Natural Resources Council of Maine, a nonprofit membership organization working statewide to protect the nature of Maine. Both are widely published natural history writers and are the authors of the popular books, “Maine’s Favorite Birds” (Down East Books) and “Birds of Aruba, Bonaire, and Curaçao: A Site and Field Guide,” (Cornell University Press).
