A 140-year-old Woodcock Exposed an Eco Villain
How an 1885 dissection unraveled a hidden story about invasive worms and the migration routes of the American woodcock in North America.
In 1887, Frederick Webster, a taxidermist from Washington, D.C., wrote a short article in a scientific journal. In it, he described dissecting a woodcock from Martha’s Vineyard that had a crop filled entirely with ferns. Why did this woodcock stray from its usual diet of invertebrates? A.J. and Gabby, hosts of the Project Upland Podcast, search for the answer—only to uncover the surprising story of invasive worms in North America.
Together with woodcock researcher Dr. Amber Roth and soil ecologist Dr. Peter Groffman, we learn how eco-engineering has destroyed native landscapes, contributed to the spread of ticks and invasive plants, and more. From woodcock migration during the Ice Age to the tobacco trade, this investigation is full of twists and turns.
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Podcast Episode Transcript
Gabby: A.J., I came across a fascinating historical account. It was written by a taxidermist who dissected an American woodcock and found its crop completely full of fern fragments—not earthworms. He said he had only ever seen woodcock crops and gizzards filled with worms before, never ferns. And apparently, no one has ever offered an explanation for why this bird ate them.
A.J.: In all my years of woodcock hunting, I can’t say I’ve ever encountered a woodcock eating ferns. So, when did this happen? Where was the bird from?
Gabby: The woodcock was from Martha’s Vineyard. It was shot by a hunter on October 17, 1885.
A.J.: So we’re dealing with a story that’s 140 years old.
Gabby: Exactly—and today, in 2025, we’re going to try to solve this mystery. Why would a woodcock eat ferns? Is there a logical explanation? To find out, I spoke with a woodcock researcher—and, as the story unfolded, I ended up interviewing a soil ecologist as well.
They both had compelling things to say about woodcock behavior, fern consumption, and a surprising ecological villain whose history is linked to this bird.
The original account was published in The Auk, a scientific journal that ran from 1884 to 2019. It served as a resource for scientists, researchers, and birding enthusiasts. In 1887, a taxidermist named Frederick Webster submitted a short article about this strange woodcock dissection.
Frederick Webster: After soaking the contents in warm water and spreading the leaves side by side, they covered a space about twelve inches square. The stomach and intestines appeared to contain partially digested leaves and nothing else, though this wasn’t determined with great care. The bird had been shot in an open marsh dotted with bushes. Small streams ran through the area, providing ample access to what should have been its usual food.
The specimen was in excellent condition—plump and fat. It was an adult female. —Frederick Webster, 1885.
Gabby: Now that we’ve heard Frederick’s story, we know a few things: when the bird died, where it lived, and that its crop was filled with nothing but fern leaves.
A.J.: When I think of woodcock, I think of earthworms. That’s what makes up the bulk of their diet—up to about 95%, I believe. But clearly, that wasn’t the case here.
Gabby: Exactly. That’s what struck me about this story. Here’s my theory: worms are rich in vitamin B, especially thiamine. Ferns, on the other hand, contain thiaminase—an enzyme that actually breaks down thiamine. So maybe this bird had too much thiamine from eating worms and instinctively sought out a food source to rebalance its system.
A.J.: So, your theory is that the woodcock may have started eating ferns to counteract a vitamin imbalance caused by eating too many worms?
Gabby: Exactly. It reminds me of a piece I wrote a few years ago about how woodcock absorb lead from their environment.
A.J.: Right—that study out of Wisconsin. If I remember correctly, it found that woodcock can absorb lead through both their habitat and their diet. Some of the birds they tested had lead levels in their bones that would be toxic to waterfowl.
Gabby: That’s right. It shows how adaptable woodcock really are. They survive in tough conditions. Still, it’s surprising to see a migrating woodcock choosing to eat ferns instead of worms—especially since they’re usually good at stopping over in areas rich in food and cover during migration.
A.J.: Exactly. So why would a woodcock choose ferns?
Gabby: Even though ferns aren’t rich in protein or fat, this woodcock chose to eat them. So the real question becomes: do woodcock actually eat ferns? And if not—if that’s not normal—why did this particular bird do it?
A.J.: Before we try to answer that, let’s take a step back and understand what the American woodcock actually is.
Dr. Amber Roth: I’m Amber Roth, Associate Professor of Forest Wildlife Management at the University of Maine. I started studying woodcock back in 1998 as a master’s student at the University of Wisconsin, and I’ve been working with them in some form or fashion ever since—either through research or fieldwork. I also band woodcock chicks in the spring with my dog. So I’ve been involved with these birds for quite some time now.
American woodcock are, in my opinion, one of the most interesting birds out there. Maybe I’m biased, but they really are fascinating. Technically, they’re shorebirds, which surprises a lot of people. When most people think of shorebirds, they picture little birds darting around the beach, feeding along the shoreline. Woodcock, on the other hand, behave nothing like that. They live in forests and shrubby wet areas, and they’re packed with quirks.
For starters, they have this incredible physical adaptation: a long bill they use to probe into the soil. Earthworms are their primary food source. And what’s really amazing is that the tip of their bill is prehensile—kind of rubbery. If you ever feel a woodcock’s bill, you’ll notice how flexible it is. That allows them to stick it deep into the soil and open just the tip to grab a worm and pull it out.
Another bizarre feature is their brain—it’s essentially upside down compared to other birds. And because of that, their ear is located between their eye and their bill. That proximity may actually help them hear the worms they’re foraging for underground.
They also have very unusual eye placement. Their eyes sit far back on their heads. So when they’re looking down to probe the ground, they can still see what’s above and behind them. If you’ve ever looked closely at a woodcock, it almost seems like their eyes are in the wrong place. But relative to other birds, that eye position is probably an adaptation. It helps them watch for predators from above while they’re foraging—because lots of things like to eat woodcock.
A.J.: Okay, now that we’ve learned more about woodcock and their behavior, let’s dig into the staple of their diet—earthworms—to help build on Gabby’s initial theory. And who better to guide us than a soil ecologist?
Dr. Peter Groffman: I’m Peter Groffman, a professor at the City University of New York. I’m an ecosystem ecologist—I have a PhD in ecology—and most of my work focuses on soils: things like carbon cycling, nitrogen dynamics, water movement, and greenhouse gas emissions. I don’t typically study the actual organisms in the soil as much as I study the processes that happen within it.
Soils are sometimes called “the poor person’s rainforest” because they’re incredibly diverse. A single gram of soil—about the size of your fingernail—can contain over a billion bacteria and meters of fungal mycelia. That’s right: in that tiny amount of soil, there are entire microscopic ecosystems at work. It might sound gross, but most of those bacteria are beneficial. And that fungal network? It helps support plant growth, recycles nutrients, and provides food for organisms further up the food chain—like beetles, insects, and, of course, earthworms, which in turn support species like birds.
While I focus more on the chemical cycles in soil, I’ve come to appreciate how important the biology is too.
Gabby: During my research, I discovered that earthworms are rich in vitamin B, particularly thiamine. Ferns, on the other hand, contain an enzyme called thiaminase, which breaks down thiamine. So here’s my theory: what if a woodcock, through its normal diet of worms, accumulates too much thiamine over time and instinctively seeks out a food source—like ferns—to help bring its system back into balance?
Now ideally, excess vitamins are simply excreted through the bird’s system. But maybe, in this case, the surplus was strong enough that the bird was driven to seek out something specific—like ferns—to regulate its internal biome.
Dr. Groffman: Back in the 1990s, I became interested in earthworms because, in many ways, they’re the charismatic megafauna of the soil. Just like we think of elephants or tigers as iconic animals in large ecosystems, earthworms are dominant players in soil ecosystems. They can reshape soil structure, alter nutrient cycling, and dramatically influence the ecosystems they inhabit.
Gabby: Dr. Groffman explained that before glaciation, North America had only a handful of native worm species. Many of them were wiped out during the last ice age. And large populations of worms didn’t return to North America until European settlers arrived.
Dr. Peter Groffman: When settlers arrived—like those at the Jamestown settlement in Virginia—they disturbed the native soil. They would dig pits, fill them with tobacco plants, and, unknowingly, also introduced European earthworms into the environment. There was actually a National Geographic article about this several years ago.
Gabby: More recently, a similar pattern occurred with the introduction of Asian worms. Anglers prefer them for fishing because they’re small and highly active—traits that make them appealing as bait, but problematic for ecosystems.
Dr. Peter Groffman: I was excited to get your note about doing a podcast episode on worms. It’s the kind of science story that often gets overlooked, but worms have a profound impact on soil ecosystems—and that impact has shifted dramatically over time. As worms have moved through space—and as different species have spread in different waves—it’s become a major focus in soil ecology.
A.J.: Just to make this crystal clear—because it’s a bit jarring—earthworms, as we know them, are not native to North America. And that brings up an interesting thought: what did woodcock eat before colonization? In William Sheldon’s 1967 book, The American Woodcock, he references fossil records showing woodcock existed over a million years ago. Some of those fossils were found in Marion County, Florida, carbon dated to the Pleistocene. That was a time when woodcock may have truly lived as shorebirds.
Dr. Peter Groffman: The last glaciation in North America ended about 15,000 years ago. Massive glaciers moved down from the Arctic through Canada and into the northern United States. They advanced through Minnesota and Wisconsin, reaching into Illinois, Indiana, and parts of Ohio, Pennsylvania, and New Jersey—before eventually retreating.
Those glaciers destroyed existing ecosystems—ripping up soil, vegetation, everything. So, if there had been earthworms present in those northern soils before the glaciers came, they didn’t survive. And earthworms move slowly. So when the glaciers retreated, the land was left with soil that no longer had an earthworm community. In fact, there are still soils in the northern U.S. today—especially in forests—that have little to no earthworm presence.
A.J.: Woodcock lived through multiple ice ages—long before invasive worms or the forests we know today. So, the question is: what were they eating back then? That’s still a mystery. But I can think of a few clues—like the sheer abundance of invertebrates that used to cover undisturbed forest floors.
A.J.: In fact, the Abenaki called woodcock “underleaf birds.” Maybe that had more to do with what they eat than just how well they’re camouflaged.
Gabby: I asked Dr. Roth what she thought woodcock were eating thousands of years ago.
Dr. Amber Roth: We do have native earthworms, but they were mostly confined to the Southern U.S. after the glaciers retreated. Woodcock have always had access to those food sources for at least part of the year. But I don’t think we really know what they were eating across their entire range over the last several thousand years.
They’ll eat other invertebrates. They’ll even eat plants if they get hungry enough. So no, worms aren’t strictly required for survival. But they currently make up a large portion of the woodcock’s diet. The question is: have worms always been such a dominant food source? That, we don’t know.
We also don’t know how their historical range has shifted. It’s possible that the introduction of European earthworms helped woodcock expand their range farther north—but it may have had little or nothing to do with food. Or it may have had everything to do with food. We really don’t know.
We also don’t have clear data on their migratory patterns before 1900. Did they always migrate to southern Canada? Maybe not. If you go back far enough, there were glaciers and snow covering much of the continent. That likely set natural limits on how far north woodcock could go. But today, where birds are comfortable is changing. It’s very possible that woodcock are now moving farther north simply because they can.
Gabby: More and more, they’re being seen farther north into southern Canada—which is funny, because Dr. Groffman talked about something very similar, but with worms.
Dr. Peter Groffman: A scientist from the University of Minnesota published a paper about what he called “ecological cascades.” It was a brilliant way of framing it. Earthworms change the structure of soil, and that unleashes a cascade of changes across the entire ecosystem.
When earthworms disturb the physical makeup and organic matter levels of the soil, they influence what kinds of plants can grow there. Once you change the plants, you change the types of insects those plants attract—and once you change the insects, you change what birds eat. So just by altering the soil, earthworms affect plants, insects, and birds all the way up the food chain.
Some of those cascading effects even include diseases and pests. Take Lyme disease, for example—it’s a major problem in the Northeast. Earthworms can change the structure of the soil in ways that affect tick habitat. Ticks live in the top layers of the soil, and when worms disturb that layer, it affects where ticks can thrive.
There are even agricultural consequences. For instance, aphids—common crop pests—are also affected by these soil changes. And this idea of earthworms as harmless or beneficial turns out to be a lot more complicated than we once thought.
Dr. Peter Groffman: Once the soil is disturbed, that opens the door for certain types of invasive plants—things like garlic mustard, purple loosestrife, Japanese barberry, and honeysuckles. There’s a term for this: “invasion meltdown.” It refers to the idea that earthworms aren’t just disturbing soil—they’re setting off a chain reaction that favors invasive species.
Another area of concern for the soil science community is carbon. Ideally, we want soils to retain carbon. But when earthworms churn through the soil, they release carbon into the atmosphere—and that contributes to global warming.
Gabby: These changes aren’t limited to plants. The spread of pests and diseases—like ticks and Lyme disease, or aphids in agriculture—can also be traced back to earthworm activity. By disturbing soil composition, worms create conditions that allow invasive plants to thrive. Dr. Groffman called this phenomenon an “invasion meltdown.”
It definitely sounds like something an eco-villain would do.
A.J.: And it’s not just a theoretical issue. Worms are mostly spread through agricultural land and waterways. A friend of mine came up with a smart strategy: overlay GIS soil data to locate abandoned farmlands rich in organic matter, which are great places to find woodcock. That method works well in southern and central New England.
But in the North Country, areas that were historically logged often lack earthworms—unless you’re near a waterway. In those places, anglers have effectively turned rivers into superhighways for earthworms. So, while woodcock can show up in lots of places, the real concentrations during migration flights are often tied to these worm highways.
Dr. Amber Roth: We’ve drastically changed the landscape through our land use. Agriculture has come and gone in different regions, and we’ve modified a lot of forests. Some areas are still farmland, but across the board, we’ve altered vegetation, introduced new threats, and even changed the climate. That has dramatically shifted where birds live and how they move across the land.
A.J.: What we’re really dealing with here are two ecosystem engineers: humans and worms. Both are actively reshaping the environment. And clearly, the thread we started pulling—with a single fern-eating woodcock—has unraveled into something much more complex.
Gabby: But we still haven’t answered the core question: why would a woodcock eat a fern?
Dr. Peter Groffman: I know ferns. I see them all the time. And now I’m really intrigued by this observation. I’m a biochemist—I don’t usually study organisms—but I’ve always been a little jealous of gut content researchers. It’s just so interesting. If you can get an animal to share its guts with you, you get a real look into what it’s been eating.
Dr. Peter Groffman: So, the idea of a woodcock eating only ferns—honestly, the first thing that comes to mind is how ferns emerge. When they come up from the soil, the fronds are tightly coiled, like fiddleheads. You can imagine that stage might be highly nutritious, maybe rich in protein or other nutrients.
But this bird was collected in October, and by then the ferns would’ve been fully mature—not in that early, nutrient-dense stage. So that kind of rules out my initial thought. It’s definitely a curious case. Maybe the bird was confused. Maybe it had a unique behavioral quirk. Or maybe it was getting something from the ferns that we don’t yet understand. It’s a question that’s way beyond my expertise, but it would be fascinating to know what woodcock were eating in northern forests around 1600 or 1500—before European earthworms arrived.
Dr. Amber Roth: I’m definitely intrigued by this fern-eating woodcock too. My gut feeling is that this isn’t something woodcock typically do. If it were common, we’d have far more accounts of woodcock with ferns in their diet.
That said, woodcock are opportunistic. They’ll eat a wide variety of soil invertebrates, including spiders. They’ve also been known to consume some plant material. Various diet studies have shown different types of plant matter in their digestive tracts—including ferns—though it’s rare. I think it largely depends on what’s available to them at the time.
Migration plays a big role in this. A woodcock moving up or down its flyway is going to encounter very different habitats and food sources. What they eat in Texas is probably not what they’re eating in New Brunswick. So, their diet needs to be flexible. They have to be able to adapt throughout the year and across their range.
It’s possible the bird was experimenting—maybe it was eating ferns alongside something else. Birds often consume materials incidentally while foraging. For example, when they pull worms or insects from the soil, they inevitably ingest some dirt too. It’s not intentional—they’re after the prey, but the soil comes with it.
We actually see this in DNA analysis of fecal samples. For example, if a bird eats a caterpillar that’s been feeding on a specific plant, traces of that plant might show up in the sample. It doesn’t mean the bird ate the plant directly—it just came along for the ride.
Dr. Amber Roth: Sometimes, the results make you stop and think. You might see something bizarre and wonder, “Why would that show up?” Then it hits you—it’s probably because the bird ingested something indirectly. If we looked closely, I bet we’d find all sorts of odd one-off things that have ended up in a woodcock’s diet. Every individual bird makes different choices. Some good, some bad.
Gabby: A.J., all this talk about woodcock, ferns, and worms really got me thinking. Obviously, we’ll never know for sure why this particular bird ate ferns. But considering woodcock migration strategies and the spread of earthworms, I have a new theory. It has more to do with weather—and location.
I did some digging and found a record of Tropical Storm Eight from the 1885 Atlantic hurricane season. The storm began on October 10th in the far southeastern Gulf of Mexico. It moved north and then northeast, making landfall between Horseshoe Beach and Suwannee, Florida, with winds up to 70 miles per hour.
By October 13th, the storm transitioned into an extratropical system over central Virginia and eventually dissipated over western New York. That’s just two days before the woodcock was shot on Martha’s Vineyard. So the storm had traveled over 2,000 miles—and by the time it ended, it was less than 500 miles from where this woodcock was collected.
A.J.: Any New Englander will tell you that storms coming up the East Coast affect our winds. And woodcock won’t fly against the wind. I don’t even think they physically can. Research by Catherine Trebilcock in 2022 showed that female woodcock migrate differently than males. Females tend to shelter in place during storms. Males, on the other hand, tend to fly to a local refuge. And storms don’t have to be hurricanes—wind events or snowstorms can have the same effect.
Gabby: Exactly. What I didn’t realize until after we started working on this episode is that Martha’s Vineyard is an island. I mistakenly thought it was connected to the Massachusetts mainland. But it’s actually seven miles offshore. And that matters, because in 1885, the island may not have had earthworms.
A.J.: As a New England native, I totally dropped the ball in assuming everyone knows Martha’s Vineyard is an island. And, of course, it’s an iconic vacation spot too.
Gabby: I did a little research on farming practices on Martha’s Vineyard, since agriculture can be a smoking gun when it comes to introducing European earthworms. It turns out that in the late 1800s, there wasn’t much crop farming on the island—mostly livestock operations. Without significant soil disturbance through planting, it’s possible that Martha’s Vineyard had no earthworms in 1885.
Which is pretty ironic, considering the subject of this entire episode. While today that’s no longer the case, we can make a solid argument that the island wasn’t a worm-rich environment at the time.
Gabby: So I think we figured it out, at least to the best of our ability. A big storm delayed her migration. She ended up sheltering on an island with no earthworms. She foraged among the ferns, likely eating invertebrates like slugs. The fern material digested more slowly, and that’s what remained in her crop. What we saw was not the full story—but the last thing she ate.
A.J.: What’s amazing is that this little story from 140 years ago brought us through ice ages, European colonization, and even the tobacco trade. We made all these unexpected stops along the way. And in the end, what started as a question about woodcock migration became a story about earthworm migration, too.
All because one woodcock might have had a rough day on Martha’s Vineyard.
Gabby: I just wish Frederick Webster could hear our theories. I’d love to know what he thought. But I’m glad we tried our best to solve his mystery.
A.J.: In the spirit of good science, all we can say is this: we have theories—now with a little more evidence to back them up.
Dr. Peter Groffman: One thing I really appreciate about this whole story is the way it brings science and society together. That’s something we try to do more of—whether it’s through outreach or engaging conversations like this.
The earthworm story gives us a way to talk about tough topics. What is an invasive species? Should we be concerned? What can or should we do about it?
And then there’s soil—something people are finally beginning to care more about. Soils are having a moment right now, and that’s great. We want people to ask: what are earthworms doing to our soils? Why do those soils matter? How do soil changes ripple up through the ecosystem?
These ecological cascades matter. If you change the soil, you might change the plants. If you change the plants, you change the insects. And if you change the insects, you change the birds. Maybe you even affect human health. That’s what makes stories like this so important—and exciting.