A few weeks ago, at about 6:45 a.m., I was at home waiting to speak live on air with Morning Edition host Michel Martin about a story I'd told, when I suddenly heard the sound of a large metallic hammer. It sounded like a machine was vibrating my house.
About 15 seconds later it happened again. And then again.
This rhythmic rattling sound seemed to come from my basement utility closet. Is my furnace broken? Or my water heater? I was worried that something like that would happen during the broadcast.
Fortunately, the noise stopped while I was on the phone with Michelle and started again later. Another sound was heard from inside the chimney, this time chirping or trilling.
Were there any animals there? I ran outside and looked up at the roof. And then I saw a woodpecker break through my metal chimney cap.
I have seen and heard many woodpeckers destroying trees. But never use it on metal. So to find out why the bird behaves this way, I called an expert. That's Kevin McGowan, an ornithologist at the Cornell Lab of Ornithology who recently created a course called “The Amazing World of Woodpeckers.”
McGowan said woodpeckers strike trees to find food, build nests, mark territories and attract mates. But when they strike metal, “what the birds are trying to do is make as much noise as possible,” he said. “And many of these people have discovered that, you know what? When you bang on metal, it makes a really loud noise!”
Woodpeckers do this primarily during the spring breeding season, and their metal rackets serve two purposes. “It basically boils down to this: All the other guys stay away and all the girls come to me,” McGowan said. “The louder the better.”
Over time, some urban woodpeckers learned that metal resonates and echoes more than wood and amplifies sound much better than wood, he added.
Woodpeckers living in rural forested areas have little access to metal, so “most woodpeckers don't have the opportunity to exhibit this behavior,” McGowan noted. City woodpeckers, on the other hand, are surrounded by all kinds of metal objects. Use what’s best in your environment to spread your message.
He added that among urban woodpeckers, “not every individual who has the opportunity to pecking at metal does so, but some birds do, and some clearly like it and continue to do so.”
The range of metals they will drum includes chimney caps, vent pipes, gutters, aluminum siding, TV antennas, drain pipes, satellite dishes and utility pole transformers, according to Brian Smith, regional deputy director of the U.S. Migratory Bird Program. Midwest Region of the Fish and Wildlife Service.
“When people and wildlife start intertwining where they live, things like this will pop up,” Smith added.
Smith said he knows of woodpeckers that bore holes in metal water heater vents, creating a “very loud buzzing sound throughout the neighborhood,” and another that flies from house to house, banging loudly on gutters and chimney caps. “I could hear him from about 10 houses away.”
“It can be pretty surprising. “What the heck is that?” said Smith. “And boy, if they can make it louder, they definitely will.”
The Macaulay Library at the Cornell Lab of Ornithology has an audio collection of woodpeckers pounding on metal, including traffic signs, ladders, roofs, and windmills.
Is there a way to stop this behavior? Yes, but there are legal issues. “This bird is protected because it is a migratory bird, so you have to get a special permit to remove the bird itself,” explained Dan Master, owner of Critter Control. Greater Boston occasionally responds to calls about nuisance woodpeckers.
Woodpeckers in particular are subject to the Migratory Bird Treaty Act and require a federal permit to capture. However, people are permitted to scare people using noise suppressors, such as recordings of the screech of a hawk, or physical deterrents, such as weather vanes, pinwheels and balloons.
Master said his company typically uses “simple Mylar ribbon” to repel woodpeckers. “One side is red and the other side is shining silver,” he said. [birds] “I don’t like the way they move and make a bit of noise when they flutter in the wind.”
Woodpeckers can scratch gutters and aluminum siding, but they are not as likely to damage metal as they would wood siding. But hitting metal, especially someone's house, with a hammer can initially cause confusion as to what's causing the noise.
“A homeowner called and said it sounded like a jackhammer coming from his fireplace.” The Master recalled. “When you hear that description, you know it’s a woodpecker.”