Hope you had a good weekend! Today’s Now I Know is a little different than usual, because I’m opening with a personal anecdote and writing a lot of this in the first person. — Dan

How Much Metal Would a Woodpecker Peck if a Woodpecker Could Peck Metal?

It began one afternoon — a jarring noise, like someone was jackhammering on a large sheet of aluminum. I didn’t think anything of it at the time, as one of my neighbors is putting a new roof and gutters on their house, and I figured the noise was the work crew doing whatever one does to make gutters fit houses. Just to be sure, I went outside, and the noise definitely seemed like it was coming from that unseen neighbor’s house.

But the next morning, just before 6 AM, the sound came back. It was too early for it to be coming from a construction crew, and it was louder than before. And it sounded like it was coming from the attic. We asked the HVAC company we use to come take a look, and they arrived later that day, cleaned the filter, and told us that the problem should be solved.

A few hours later, the sound came back. We went outside again — and again, it sounded like it was coming from the neighbor’s house. But the next morning, the sound was even louder than before, so I walked through the house trying to find the source. It was particularly loud in the basement, as if it were coming through the pipes. I walked outside to check the compressor, and that’s where I saw it: the woodpecker, perched on the top of our metal chimney pipe, banging away.

And I wondered: why is a woodpecker pecking at metal? Was it going to damage my house? Was this the stupidest woodpecker on the planet?

The answer to the last one is no — in fact, it turns out that this woodpecker was, probably, particularly smart.

Woodpeckers, as their name suggests, typically peck at wood. They do so, as Mass Audubon (the Audubon Society for Massachusetts) explains, “when woodpeckers drill, they actually chip out wood and create holes in search of food or to create cavities, potentially sites for nesting or roosting. In the fall, woodpeckers excavate several roosting holes in preparation for the coming winter. In the spring, a resurgence of drilling activity occurs in preparation for the nesting season.” Basically, they’re trying to build a home or they’re hungry, hoping to encounter bugs or other snacks a tap-tap-tap into the wood. But the woodpecker on my roof wasn’t looking for food. It was looking for love.

In the spring of 2024, Sacha Pfeiffer, a reporter for NPR’s All Things Considered experienced the same thing I did. She described it as “a loud, metallic hammering” and her investigation was similar to mine: “It seemed to be coming from my basement utility closet. I wondered if my furnace was breaking or my water heater and what I would do if it happened when I was on the air. It stopped while I spoke [on air] but started again later. This time, I heard another sound, possibly inside my chimney.” (As a radio report does, Pfeiffer recorded the sound. If you want to hear it for yourself, you can click that link. I also captured the sound at my house, which you can listen to, here.)

Pfeiffer determined that a woodpecker was to blame and went through the same questions I did — and being a reporter, she found the answer. According to Kevin McGowan, at the Cornell Lab of Ornithology. McGowan explained that woodpeckers — male woodpeckers, specifically — claim territory and attract mates by making a ruckus, and the louder the noise, the better. “What the birds are trying to do is make as big a noise as possible. And a number of these guys have found that - you know what? - if you hammer on metal, it's really loud.”

The good news, for, well, me: it’s very unlikely that the metalhead woodpecker is going to do meaningful damage to the chimney pipe it’s using as a drum. The bad news? Once a woodpecker finds a way to make a loud noise, they typically stick with it through the spring and sometimes into the summer — and there’s not much one can do to make them go away.

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More About Woodpeckers

Today’s Bonus fact: If the woodpecker waking me up every day is, indeed, smarter than the average woodpecker, that may be a bad thing for it in the long run. All that head-thumping pecking would give anyone a headache and, ultimately, a concussion or worse. For a while, researchers theorized that woodpecker skulls were very good shock absorbers, but according to a 2022 study, they don’t have anything special going on. Rather, they’re just small. Scientific American explained:

Having a smaller brain also helps the woodpecker from suffering from all that banging — so maybe being a big-brained bird isn’t such a good thing after all.

From the Archives: A Tree* Grows* in Brooklyn*: The bonus item is about my least favorite bird (for now).

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And thanks! — Dan