The Mystery of Grouse Drumming: From Thunder to Artificial Intelligence
This podcast episode uncovers the mystery of how ruffed grouse create their drumming sound, why they do it, and how it aids biologists in their conservation work.
In this episode, Gabby and AJ explore the mystery of ruffed grouse drumming—starting in the 1700s, when naturalists first theorized about the sound, and tracing the evolution of human technology that finally unlocked the truth behind this unique behavior. Along the way, they talk to biologist Alaina Roth, Wisconsin’s statewide ruffed grouse specialist, who sheds light on grouse life history, drumming counts, and how technology is transforming wildlife surveys. This episode covers everything from historical myths and early scientific discoveries using cameras to modern AI-driven drumming surveys and the critical role of habitat in grouse conservation.
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Podcast Script from the Mystery of Ruffed Grouse Drumming
AJ: One thing I love about turkey hunting in the spring is listening to ruffed grouse drum. Today’s episode is going to explore the biology of drumming and the science of drumming counts. It’s actually an insane story that takes us from the 1750s all the way to artificial intelligence.
Gabby: A.J., I have something embarrassing I need to admit to you. Yes. I’ve never heard a ruffed grouse drum. I’ve never even seen a ruffed grouse. As a mega bird nerd, the only interaction I’ve ever had with a ruffed grouse is picking up their poop for a research project while I was an undergrad. Which is still cool. It still seemed like fresh grouse sign, but I never actually saw the bird.
AJ: Well, today we are going to take you as close as we can to grouse drumming without experiencing it in the wild. This episode is going to start with unlocking the mystery of how male ruffed grouse make their drumming sound. Then it’s going to explore the science and significance of drumming counts, with a few crazy sidebars in between. And an apology in advance—the audio quality in our interview was a little degraded but still clear enough to use.
AJ: Well, Gabby, I’ve come with receipts, so to start off I’m going to play you and our audience a recording of a grouse drumming.
Gabby: So if I heard this sound out in nature, I would not think that it’s originating from a bird. I am more familiar with other bird drumming sounds, like woodpeckers using their beaks to drum holes into dead trees or cockatoos using simple tools like a stick. But I am totally unfamiliar with this sound that the ruffed grouse makes, which apparently comes from their wings.
AJ: And here’s an insane fact about that. Ruffed grouse are the only bird species in the world that drums like this. They’re alone in this method. And because of how unusual this method is, curious naturalists, biologists, and bird nerds like me and you have been inspired to learn more about this behavior.
Gabby: So, given its unusualness, how did scientists start to figure out how these birds were making this drumming sound?
AJ: So we’re gonna hop into our time machine and go all the way back to the 1750s to a botanist named John Bartram, who wrote a letter to the father of British ornithology, George Edwards, about a bird—and I love this name—he called the Roughed Heath Cock.
John Bartram: There is something very remarkable in what we call their thumping, which they do with their wings by clapping them against their sides. As the hunters say, they stand upon an old fallen tree that has lain many years on the ground where they begin their strokes gradually.
At about two-second intervals, they repeat them quicker and quicker until they make a noise like thunder at a distance, which continues from the beginning for about a minute, then ceases for about six or eight minutes before it begins again. The sound is heard nearly half a mile away, by which means they are discovered by the hunters, and many of them are killed.
I have shot many of them in this position but never saw them thump. They mostly see me first and so stop. They commonly exercise in thumping in spring and fall at about nine or ten in the morning.
Gabby: So John Bartram made an honest attempt at trying to interpret how a ruffed grouse made their drumming sound. A.J., are you familiar with any other historical accounts that described theories on how grouse drum?
AJ: Alright, so there’s been a lot of theories made over the years. Most of them are old wives’ tales. I can even remember stories from when I was young—and I’m only in my forties—of people saying that grouse slapped their wings on hollow logs to make the drumming sound. A theory like this doesn’t hold up; grouse drum on rock walls, glacial erratics, really anything, including logs that aren’t hollow. So it certainly has a history of being a mystery that has inspired some crazy ideas.
Gabby: Thankfully, I know someone who thinks about ruffed grouse a lot—the Wisconsin Department of Natural Resources ruffed grouse specialist, Aliana Roth. She can help us establish a bit of ruffed grouse life history before we go any deeper.
Aliana Roth: So my name is Aliana Roth.
I work for the Wisconsin Department of Natural Resources and my role is split in two. A large majority of what I do day to day is the Eau Claire County wildlife biologist position. That’s a lot of habitat management, wildlife surveys, and property management, focusing on one county in north-central Wisconsin.
And then the other portion of my job is to be the statewide ruffed grouse specialist. That involves a lot of statewide coordination. We have a species management plan, adopted in 2020, with many goals and objectives for ushering that species management into the future. So my job is to oversee and coordinate the goals of that plan.
I always had a pretty strong interest in game species management. That was just something I always gravitated toward because of my hunting background. When I was looking for graduate schools, I applied to many different programs, and the ones that really piqued my interest dealt with game birds.
I ended up working with wild turkeys, and I just think upland game birds are really important for a lot of reasons. Ruffed grouse are our most abundant upland game bird here in Wisconsin. They are native to the area. It’s a very small bird, about one pound, and they’re small but mighty.
They are what we as wildlife biologists would call a typical r-selected species. They have very short lifespans—only about 18 months on average—and they cope with that short lifespan by reproducing prolifically. So it’s a short and fast life, and they don’t spend a lot of time putting energy into raising their young. It’s more of a quick crash course and then onto trying to reproduce and make the next generation.
So, they are our most popular game bird here in Wisconsin, very popular amongst hunters, and that’s kind of a quick rundown of the ruffed grouse.
Gabby: Okay, so now that we know some life history information about ruffed grouse, I’m starting to see how advancements in technology helped humans understand this drumming behavior.
If we couldn’t record the sound, how could we describe its volume and speed to others? If we couldn’t photograph or film it, there’s almost no way to tell that a grouse’s wings aren’t technically touching the log they’re drumming on—or even their body.
AJ: So human technology was critical in uncovering this mystery—the invention of the camera in this case and ultimately the advancement of that technology.
In 1929, almost 200 years after John Bartram’s observation, the schedule of the 47th meeting of the American Ornithologists’ Union listed a 15-minute presentation titled The Courtship of the Ruffed Grouse by Arthur Allen of Cornell University.
Going frame by frame, Arthur Allen proved that a male ruffed grouse’s wings were producing the sound with air.
Gabby:
So I wanted to look up a clear definition of what a ruffed grouse drum is. I remember, A.J., you told me about a book called The Ruffed Grouse by a biologist named Gordon Gullion. So I looked it up and found that Gullion wrote:
“The drumming sound is made by the bird leaning back on his tail and striking his wings against the air violently enough to create a momentary vacuum, much as lightning does when it flashes through the sky.”
AJ: “A momentary vacuum, much like lightning.” No big deal.
Now that Allen knew how they do it, he still set out to answer an even more obscure question—which is how grouse learn to drum.
Arthur Allen: After a few minutes of reconnoitering, he mounted the log and almost immediately assumed the drumming pose, first patting the log with his feet as though to test the stability of the spot he had chosen.
Then followed the quick stroke of the wings, another and another, and finally, the roll and a blur of wings that made the dead leaves fly from in front of the log. There was no question that he knew instinctively what a drumming log was for and knew how the drum should be produced, but he made scarcely a sound.
Indeed, it required nearly two weeks of constant practicing before the bird’s drum sounded like that of a wild bird. Since this bird had never seen nor heard another grouse drum, I think we are justified in concluding parenthetically that grouse inherit an instinct to drum, just as I believe other birds inherit the instinct to sing.
Gabby: This is really interesting to me because I am more familiar with songbird research than with ruffed grouse research.
Something I’ve learned through studying songbirds is that, yes, they’re born knowing how to sing—they inherently know how to sing—but they don’t know how to sing correctly. Their songs usually sound immature, just as immature as the bird itself. They need to learn the correct cadence, tones, and volume from their parents and other mature breeding adults to properly learn how to make their song.
And this seems to also be true about ruffed grouse drumming. They need to practice to get it right.
AJ: The novelty of something like this only makes me love ruffed grouse that much more.
Gabby: So if other birds—songbirds—are using their songs for breeding purposes, does that mean that ruffed grouse are using their drumming for breeding purposes as well?
AJ: So ruffed grouse in the springtime are absolutely drumming for mating purposes—to attract a mate.
They also drum for dominance reasons in the fall, and we will get into that later. But for now, birds drumming in the spring brings up kind of our first step in science-driven data: a form of indexing known as grouse drumming surveys.
And of course, Aliana helped us understand what exactly a grouse drumming survey is.
Aliana Roth: So drumming counts are a basic survey that we have done here in Wisconsin since the 1960s.
It’s a survey where biologists, technicians, and even volunteers go out on a designated route—ten miles long with ten stops. Every mile you stop, you listen for four minutes, and you count the number of ruffed grouse drums you hear during that time period.
The surveys are conducted in spring, which is during their breeding season when they’re doing the most drumming. We go out in the early morning hours, which tends to be the most prolific time for drumming activity. So it gives us an index of our population abundance.
For a lot of species, we are not actually trying to count the number of animals that exist out there. When you think about ruffed grouse or turkeys, those are two main examples where we use either harvest or a survey as an index of how the population is doing, instead of trying to estimate the actual population number.
So for ruffed grouse, that drumming survey is an index because it provides one very important piece of the population equation: the abundance of males that are drumming.
It gives us an index of growth and depression in the population number. And it’s also important for presence and absence. Like I mentioned before, in southwest Wisconsin where we historically had ruffed grouse and now have very few, we continue to do those survey routes to see if any new populations are emerging in certain areas after habitat treatment.
Gabby: Aliana mentioned this concept of an index. An index is a simple statistical measurement used to track changes in population sizes or abundances. Indices are especially useful when counting exactly how many individuals make up a population is impractical or even impossible.
So for crystal clarity, drumming counts are indexes, not a population count.
AJ: Another common example of an index can be gathered from wing and tail surveys. If you’re unfamiliar, wing and tail surveys are commonly used ways for wildlife biologists to gain information from hunters.
Hunters submit a wing or a tail from the birds they killed, and biologists can determine whether the hunted birds were male or female, and mature or immature. Biologists can use these numbers to estimate male-to-female bird ratios as well as estimate whether more immature or mature birds are present.
Gabby: One thing worth noting here is that just because a lot of birds are drumming in the spring, that doesn’t mean there will be insane ruffed grouse numbers in the fall.
Chick mortality—which kills the most ruffed grouse—happens in the spring after the males are done drumming. How much cold, rainy weather occurs after the drumming season is a better indicator of how many grouse will be in the woods come fall because grouse chicks struggle to thermoregulate in those conditions, and many die from exposure.
AJ: So I would like to take a sidebar on fall drumming behavior. I mentioned earlier that ruffed grouse can also drum in the fall, but for dominance reasons. Fall drumming is a great indicator of solid grouse numbers for the season and it gets down to some pretty obscure biology of where grouse choose to drum.
The short of it is that drumming birds in the fall means an abundance of males looking for and defending drumming sites.
Gordon Gullion: Historically, depending on whether or not they are repeatedly used by successive male grouse, logs and centers are defined as perennial or transient.
Annually, a log may be used as a primary, alternate, or perhaps incidentally as a secondary drumming log. During drumming duels, logs or objects with no prior history of use may be used briefly as challenge sites. The status of the male grouse established on a log in relation to his predecessor may be that of a new drummer (on a log not used before), a replacement drummer, a displacement drummer (having routed his predecessor), or a repeat drummer.
The social status of the male grouse established in an activity center may be that of the dominant drummer; the subdued alternate drummer; a satellite drummer sharing a center on nearly even terms with the dominant male; or the non-drummer, who is apparently not persistently associated with any definite log or activity center. (Selection and Use of Drumming Sites by Male Ruffed Grouse, The Auk, 1967)
AJ: Gordon Gullion is perhaps the most renowned ruffed grouse researcher within the community, and his work on the science of drumming is unmatched.
His career spanned more than 60 years, and he is deserving of his own Project Upland podcast episode. But he is unavoidable on this topic, and his work helps us understand the connections between drumming and habitat needs.
Gullion’s work includes the study of over 2,000 drumming sites that have been boiled down to some of the most important information in drumming research, even 40 years after it was written.
Gabby: Through his work, Gullion even found fascinating time patterns.
While the average time between drums was four minutes, ruffed grouse that were not engaged by either a mate or a challenger would decrease drumming in a pattern of four-minute intervals.
To quote Gullion’s research:
“At other times, when a single bird is drumming and not being answered by others, the intervals between drums may be at multiples of four minutes—that is, at eight, 12, or 16-minute intervals. If you hear a drumming break decrease in length, it is an indication of a male bird being excited by the presence of another bird. At this point, drums can happen as often as one minute apart.”
AJ: So when we talk about drumming counts now, understanding how picky a male ruffed grouse is when it comes to drumming sites, drumming counts can also be an index of good habitat.
And we’re going to let Aliana describe that a little more.
Aliana Roth: Yeah. So, as I said, they are a very short-lived species, and they have a few significant things they need to check off their lifecycle list in that short amount of time.
They are born precocial, which means that as soon as they hatch—on the day they hatch—they’re up and moving with mom. That’s different from altricial songbirds that stay in the nest and are featherless, helpless, and blind for a while.
Ruffed grouse are basically born running on the ground right off the bat.
For the first two weeks of their life, they are flightless. So it’s really important for them to have super high-quality brooding habitat that typically looks like open areas with a lot of forbs—flowering plants—that will host a lot of insects, which are very protein-rich and help them grow those flight feathers.
After two weeks or so, when they can start to fly and evade predators, their chance of survival goes way up. But those first two weeks are pretty risky; survival is pretty low. So it’s important for them to have that really open herbaceous, shade-intolerant habitat next to very dense, thick forest cover.
That way, if any sort of predator comes by—whether it’s an aerial predator like hawks or owls or a ground predator like raccoons, foxes, or coyotes—they have dense cover they can escape to very close by.
That open cover is important for foraging. Once they get older and head into fall, they need different food sources. Once they become adults, they kind of move away from insects and rely much more on hard and soft mast.
In Wisconsin, that would be acorns, hazelnuts, blackberries, raspberries, and similar foods. All those plant species are also shade-intolerant, so young successional forest habitat is a huge part of their lifecycle.
As they move into winter as full-fledged adults, they rely on slightly older forest—typically about 15 to 25 years old—which produces catkins (the male flowers of those forest tree species), an important winter food source.
So throughout their lifecycle, they really rely a lot on young forestry. Consider them a habitat specialist, but they need a patchwork of different forest ages to meet all their lifecycle needs.
Gabby: Another fun fact about ruffed grouse is that healthy populations commonly exhibit something referred to as a 10-year population cycle. This means their populations predictably increase and decrease, and the cycle repeats every 10 years.
Additionally, grouse are often referred to as a bellwether species. In other words, if their population declines beyond the predictable and recurring 10-year decline, it sets off alarm bells.
Aliana Roth: Wisconsin has been an interesting case study because as recently as the 1980s and 1990s, we had very good grouse populations spread across, I would say, two-thirds of the state.
We had very healthy populations in the southwest part of Wisconsin, which we call the Driftless Area, a couple of decades ago. Unfortunately, we’ve experienced some pretty significant habitat loss in that area, and ruffed grouse have become almost undetectable.
We noticed that as those populations declined in that area, that 10-year cycle became less and less pronounced.
In northern Wisconsin, we still see a strong relationship with that 10-year cycle. Here, our cycles peak typically in years ending in nine or zero. Then around years ending in four or five, we’re in our troughs or valleys.
So that 10-year cycle has remained fairly consistent for the northern part of the state.
There’s been a lot of talk about why that cycle happens. I don’t know that scientists have ever landed on an exact reason with hard evidence.
The leading theory I’ve heard in recent years is that it has a little to do with goshawk populations and how their populations cycle—not unlike what we see with snowshoe hares and lynx in some classic studies.
I don’t know how thorough and rigorous that theory is, but that’s the main one I’ve heard from other researchers.
AJ: So Gabby, I am going to move to the technology story here—advancements in how drumming counts can be conducted using remote sound recording equipment and interpreting data using artificial intelligence.
I sent you a paper that I found when I wrote an article about grouse drumming, which you edited. The name of that study was The Automated Recognition of Ruffed Grouse Drumming in Field Recordings.
Aliana Roth: I actually got to work on a very similar project when I was in graduate school.
I worked for Louisiana State University, and we were deploying these autonomous recording units—ARUs—in South Carolina on a wildlife management area to detect gobbling turkeys.
It’s pretty much the same concept, but for a different species.
They’re basically just recording units that you deploy up in the trees with a microphone. They have chips, you insert batteries, and every week or so you go out and collect the chips.
Then you take that raw data and put it through software that you can program to search for all sounds that fall within the megahertz range of what a drum would sound like.
So these things are recording all the time—or for whatever program you set them to. For grouse, you’d probably record early in the morning and then turn them off during the day to save battery and storage space.
You put the recordings through a software program and tell it, “I only want to see this frequency because this is the frequency that drums should fall in.” It clears out all the other data and gives you only sounds that fall within that range.
There’s potential for this to be a very effective tool for things like ruffed grouse, turkeys, warblers—whatever.
Right now, our survey routes are confined to roadways because that’s where it’s time-efficient. We couldn’t walk 10 miles and be as efficient. But with ARUs, we could deploy these in more remote areas and reach more distant landscapes.
The thing I keep thinking about is budget. What’s limiting me is my budget. I’m not going to be able to deploy these everywhere because they are expensive.
But once you get past that cost, you save a lot of staff time. To go out and check these recorders and collect the chips takes about 10 minutes compared to someone going out and doing a three- or four-hour-long survey.
I think you would end up saving money in the long run because you wouldn’t need as much staff time or mileage input every single year to conduct survey routes.
I think there’s potential for it to be cost-saving.
Gabby: Of course, I read the paper after you sent it to me. I love reading scientific papers, especially ones about birds—especially ones that include the intersection of wildlife ecology and modern technology.
But technology always leaves me feeling torn.
Yes, I love that technology like this can help make the work of biologists easier. I think Aliana made a great point: the automation of recognizing drumming sounds and turkey gobbles really speeds up the process.
It allows biologists to use their time more wisely—like restoring wildlife habitat or actively being out in the field.
But there’s always a catch.
In the case of these recording units, where are the mined resources necessary for their chips sourced from? Are they made overseas and shipped to North America? How many data centers are needed to support the AI program that learned to recognize drums and gobbles?
Does it make sense to eliminate our reliance on humans when it comes to collecting data on birds? Is it actually cheaper, or are there long-term costs—monetary or ecological—associated with this?
That said, the technology we’re talking about here is pretty small-scale: an AI program that can recognize a specific subset of sound frequencies.
Personally, I prefer not to make broad generalizations, so I am not anti-automated recognition services. But as a proactive person, and with recent governmental decisions in mind, I’m hesitant to see what an increased reliance on technology might lead to.
However, it may be our only option if wildlife research is defunded.
AJ: Unfortunately, this is the part of the story that’s becoming an increasing issue—funding.
Serving on the New Hampshire Fish and Game Commission has made me all too aware of the challenges of funding basic work like indexing and staffing issues.
Wildlife agencies throughout the country are facing these problems to varying degrees, and technologies like this could hopefully help us do more with less—provided an agency can get past the initial investment.
Something like this is a great way to leverage local nonprofits to help a state agency buy equipment. It’s something fully in our control as hunters and people who care about this science.
I also get excited about the stability of data using technology like this. Not that biologists are out there making massive human errors, but things like hearing issues, someone forgetting to turn a truck engine off, or even how often the survey is conducted could really become things of the past.
Aliana Roth: Especially if we’re worried about ruffed grouse, I would say we’d have more time for habitat management—and to me, that is the most important thing we can do for ruffed grouse.
If you think about all the things that can impact a ruffed grouse throughout its life and cause mortality—disease, overwinter mortality, predation, climate stressors—it’s a lot.
I always explain it like this: if you’re a person and you have the flu, you’re going to recover much faster if you have a warm, climate-controlled house, plenty of food, and a big cozy bed.
But if you get the flu and you’re homeless or living in the woods, you’ll have to try to keep warm, make a fire, and find resources.
That’s very similar to a ruffed grouse.
They’re going to be much better adapted to overcoming external stressors like climate, predation, and disease if they have high-quality and high-quantity habitat to live in.
If they’re trying to survive in mediocre or low-quality habitat, they won’t cope as well.
There are also climate stressors affecting ruffed grouse.
In Wisconsin, one major thing is that they are highly correlated with quaking aspen—a boreal species expected to move out of Wisconsin. We’ll need to find some kind of surrogate habitat that works for them.
Another major factor is that ruffed grouse rely on snow roosting, where they dive into piles of light, fluffy snow to roost overnight for predator protection and thermal cover.
As we get fewer predictable snow events, that’s going to be harder. So they’ll need more conifer cover.
There are a lot of climate factors at play, and at UW Madison, several students are working diligently to study some of those climate models and how they’ll impact ruffed grouse.
AJ: Today we spared everyone some of the more obscure parts of Gullion’s research, and I would certainly encourage anyone who’s interested in ruffed grouse to read his book.
The book was originally titled Grouse of the North Shore. It eventually got republished as The Ruffed Grouse. It can be a little difficult to find copies—they’re a little expensive. I have a copy, and it’s well worth it. It’s one of my most favorite books when it comes to the biology of ruffed grouse.
His career was significantly tied to the Ruffed Grouse Society, and we can thank them for so much of the funding that went into his research and his legacy.
Gabby: This exploration of ruffed grouse drumming is a great example of how complex and interesting ruffed grouse truly are.
Although these birds can be finicky—as AJ has attested—they are a symbol of a diverse, healthy ecosystem.
And as someone who’s also a huge Aldo Leopold fan, all this talk about ruffed grouse makes me think of his famous quote:
“Everyone knows that the autumn landscape in the Northwoods is the land plus a red maple, plus a ruffed grouse. In terms of conventional physics, the grouse represents only a millionth of either the mass or the energy of an acre, yet subtract the grouse and the whole thing is dead.”
Aliana Roth: It is unmistakable. It makes me very grateful to live where I live.
I love living in northern Wisconsin. I think it’s so special here. I think it’s a very underrated place, and I’m just very glad to be here.
To me, yeah, hearing a ruffed grouse drum is like an emblem of northern Wisconsin. That’s kind of the gut feeling I get.
AJ: So if you enjoyed today’s episode, we’d certainly love your support. If you head over to our Patreon, we are an independent media group. This research is done in-house—we obviously nerd out over this.
You can go over there and listen to the full interview with Aliana, as well as get links to the paper we talked about in this episode.
You can communicate with us, the hosts and other staff, see behind-the-scenes interviews, nerd out in all sorts of ways, and continue the discussion on this fascinating piece of history and science about drumming ruffed grouse.
Gabby: This episode was produced by myself, Gabby Zaldumbide, A.J. DeRosa, and Jennifer Wapenski.
The editing of this episode was done by myself and A.J. DeRosa.
Special thanks to the Wisconsin Department of Natural Resources’ ruffed grouse specialist, Aliana Roth.