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The following is an excerpt from Herb Wilson's column, "For the Birds," published in the Waterville Morning Sentinel and Kennebec Journal. Tower Kills Human activities greatly influence bird populations. You can find birds that profit and those that suffer from almost any human alteration of our landscape. Window kills are a threat to birds that frequent feeders, as most readers of this column will know. A less appreciated threat to birds is communication towers. Consider the following examples of tower-related mortality. Beneath a 1,482-foot-tall tower in central Florida, 1,592 dead birds of 37 species were found shortly after dawn on September 29, 1970. On the morning of October 8, 1955, approximately 4,000 birds of 62 species were found dead below the base of a 673-foot TV tower at the Tall Timbers Research Station some 20 miles north of Tallahassee, Florida. On Jan. 22, 1998, an estimated 10,000 Lapland Longspurs died one foggy, snowy night in western Kansas from collisions with a television tower that was "only" 420 feet high. Recent estimates indicate that about four million birds a year in North America die from collisions with human-made structures. Why do towers cause such bird mortality? Most of the tower mortality occurs during migration. Most songbirds as well as a number of other birds migrate at night when the risk of predation is lower and the cool air helps keep the birds from overheating due to the awesome exertion required in migratory flight. On overcast or stormy nights, the lights on communications towers become a lethally disorienting signal. The birds apparently mistake the lights on the tower for the moon. The birds fly around the tower, sometimes flying into the tower, sometimes into the guy wires that help support the tower, and sometimes into other birds circling the tower. Some birds die from exhaustion as they fly round and round the tower. The radio signals these towers transmit may interfere with the ability of migrating birds to detect the earth's magnetic field. This effect may explain why birds fly continuously around the towers. What can be done to decrease bird-tower deaths? First, towers should be clustered. Towers for transmitting radio signals, TV signals, telephone calls and other electronic signals should be located in the same area to minimize risk to migrating birds. No permits should be issued for tower construction in areas of known high migratory bird concentrations. The type of lighting can reduce bird mortality. When Ontario Hydro replaced the continuously shining spotlights on its emission stacks at six electricity generating plants, bird collisions declined dramatically. Deaths from tower collisions are likely to increase in the coming years. Television stations converting to the digital broadcast format intend to erect more than 1,000 towers in the next few years, each at least 1,000 feet tall. Prudent location of these towers will help to temper their effects on birds. An interesting Web site showing the locations of communications towers in the 50 states can be found at www.towerkill.com |
A man studying turkey vultures lies next to a dead calf in the desert for days, waiting for the birds to land on him. Is this scientific research, asks a newspaper reporter in an e-mail that reaches Colby's resident bird expert, or nutty obsession?
"He isn't going to have any success until he gives off ethyl mercaptan–that's the smelly stuff, sulfur and mercury in one," Herb Wilson answered with amiable matter-of-factness–explaining that vultures locate their prey not by sight but by smell. In other words, the fellow has to be dead to study vultures this way. But if he's really close to the calf, might they land on him, too? "I suppose it's possible," Wilson said, sounding like an expert witness admitting it's possible a bird can ride a bicycle. "But it's pretty darn peculiar."
Associate Professor of Biology, ecologist and ornithologist Herb Wilson is careful not to sound elitist, but roosting in his office in Olin 216 is some decidedly sophisticated equipment for his study of birds. The room looks like the office of a scientist in a movie: prominent computer screen, spotting scopes, a video camera, directional tape recorders and floor to ceiling bookshelves crammed with hardback books, texts, binders of course materials and virtually complete sets of all four major ornithology journals. A side door opens into his laboratory.
"Most of what I do relies on statistical analysis, so it's based on a combination of things accumulated over time," Wilson said, disclaiming any sudden new wrinkle or bee in the bonnet like turkey vultures and a dead calf.
To demonstrate, he swivels to his computer screen, which glows with what looks like a series of deep blue bar graphs in the shape of horizontal hourglasses separated by snowflakes. As a white-throated sparrow sings out, the computer program graphically represents the vocalizations as sonograms, those hourglass and snowflake patterns on the screen. Wilson sings a translation of the bird's song–"Poor Sam Peabody Peabody Peabody," the first two syllables slowly, then speeding up: Pooor Sammm PeabuddyPeabuddyPeabuddy. Then, moving his cursor on the screen, he transposes Poor Sam and the Peabodys. The bird sings, "Peabuddypeabuddypeabuddy pooor sammm." Canary–the name of this program from the Cornell Laboratory of Ornithology–enables him to dissect syllables to try to understand what they mean to the birds. He can tape the song and play an endless loop to learn how birds in the wild will respond to the made-up sound.
Maybe different syllables mean different things, he says, or it may be the song itself that's important and not the individual syllables in a particular order. Or certain birds "might hold a syllable longer; they might drawl; they might have a different pitch," he explained, making the birds sound like plain folk who understand each other despite different regional dialects. It's possible, he says, that the sound may be made for a mate alone rather than a non-mate. It's even possible that the birds may not be interested in the made-up sound at all.
Whether he's teaching his ornithology course at Colby, leading a group of local amateur birders to Togus Pond to spot osprey and bald eagles or attending a talk at a meeting of professional ornithologists in Montana on the function of song in the red-eyed vireo, W. Herbert Wilson Jr. is whole-heartedly taken with feathered creatures–their vocalizations, their structures and differences within species, their feeding habits. A member of all four major ornithological societies, he attends at least one meeting of each every year to check out research similar to his own or to happen across an interesting talk on, say, the DNA of crows. "That's serendipity," he said. "But most important, it's a meeting ground for ornithologists–just talking to someone over coffee about chickadees."
Wilson was in charge last June of lining up the speakers for a meeting of the Wilson Ornithological Society (named for famous birder Alexander Wilson but no relation). One of the enlistees, Rachel Zierzow Jennings '96, who presented her research on hummingbirds in the Sonora Desert, began studying the birds in Sidney Bog after she took Wilson's Jan Plan course in winter ecology and his ornithology course the following spring. "I loved it," said Jennings, now in a Ph.D. program at the University of Texas at Austin. "I spent the next few summers working with him and others. He's really the person who sparked my interest."
The laboratory adjoining Wilson's office is his own dedicated research lab. Each of the students doing independent research with him has a key to enter at any time, and equipment does not have to be dismantled for classes. Wilson gives high marks generally to the space and equipment of the new F.W. Olin Science Building and to the research software and assistants the College has made available to him, all important in his teaching.
He turns back to his computer to check an e-mail from Erin Vogel '95. Did he mention, he asks, the six published papers written in collaboration with students who were summer or academic-year research assistants? One of those former fledglings, Vogel is currently at SUNY-Stony Brook studying . . . monkeys? Yes, Wilson says, birds and monkeys share enough similarities in foraging behavior to be of interest. In fact, he says, he's done more research on winter foraging and the ecology of chickadees and nuthatches than he has with vocalization.
