Biology Archives - Research Blog

Duke biology professor Paul Manos, Ph.D., looking at peat moss with Wild Ones members Gurnoor and Dhruv.

The Wild Ones club recently visited the Duke Forest with biology professor Paul Manos, Ph.D., and herpetology professor Ron Grunwald, Ph.D., to look for salamander eggs and other early spring delights.

It was warm and sunny, and wildflowers sprouted up alongside the trail, but most of the trees were still bare. “It’s kind of nice to look in a forest without any leaves,” says Manos. “They get in the way a lot.” We examined winged elm and shagbark hickory at the trailhead, then windflower and bluets right beside the path. Many early spring wildflowers take advantage of the higher levels of sunlight that reach the forest floor before trees develop leaves.

A shagbark hickory tree in the Duke Forest. “Shagbark” refers to the peeling strips on the trunk. The word “hickory,” meanwhile, comes from an Algonquin word for both the tree and a food made from pounded hickory nuts.

Manos was delighted to find a patch of sphagnum moss beside the trail. He says sphagnum, also known as peat moss, is usually found in higher latitudes, like the United Kingdom and Canada, where it grows in huge fields known as moorlands or quaking bogs.

When we reached a small pond, Grunwald swept a long-handled net through the water and leaf litter and pulled out a gelatinous glob that promptly became a highlight of my week/month/year: spotted salamander eggs. I don’t know what the rest of you spent your childhoods doing, but I spent a good portion of mine looking for frog eggs (and sometimes finding them) and wanting to find salamander eggs (and never finding them). But here they were, in front of me, tinted green with algae and glinting in the sunlight and close enough to touch.

Bluets are members of the coffee family, which Manos says is “known for having a lot of chemical diversity.” Many of the members of that family grow in the tropics, but some, like this bluet, live in more temperate regions.

This strikes me as an appropriate retort to many unrelated things. Calculus test? Yeah, okay, but I saw salamander eggs. The grosbeaks that Wild Ones went looking for two weeks ago are still thwarting me? Yes, and I still haven’t gotten over it. However: salamander eggs.

Sphagnum moss. It is wonderfully moist and spongy.
Photo by Lydia Cox, one of the student leaders of Wild Ones.

The egg mass was less firm and less slimy than I expected. It felt remarkably similar to jelly. “This gel,” Manos says, “apparently doesn’t allow oxygen to move through it very well,” but the developing spotted salamander larvae need oxygen. The solution is ingenious: a partnership with green algae. A species of algae grows on the egg masses and penetrates individual eggs, and eggs with more algae grow and develop faster.

The algae are photosynthetic, creating carbon and oxygen products from carbon dioxide gas and sunlight. That process likely provides supplemental oxygen to the salamander embryos, and one study found that the salamanders also absorb carbon produced by the algae’s photosynthesis.

Herpetology professor Ron Grunwald with spotted salamander eggs.

That carbon fixation is the first known example of carbon transfer from algae to a vertebrate host, though similar partnerships have been found in invertebrates, and the authors of the study speculate that similar processes may be occurring in other amphibians as well.

The particular species of algae that grows on spotted salamander eggs is in the Oophila, which according to Manos means “egg lover.” The partnership, however, is temporary. “It’s a very short-lived, ephemeral story,” Manos says.

“This is the best day of my life,” says Michelle, a Wild Ones member, while holding spotted salamander eggs. Comments from other students included “This feels weird,” “That is a sublime experience,” and “Nature’s fidget.”

In addition to the spotted salamander eggs, Grunwald also found a marbled salamander larva. Marbled salamanders and spotted salamanders are in the same genus, but they have different approaches to breeding. Marbled salamanders, Grunwald explains, lay their eggs in the fall “where they think a pond is going to be” instead of waiting for ephemeral pools to develop in spring. How do they decide where to lay eggs if the pond isn’t even there yet? Scientists aren’t sure, but salamanders “live in a chemical world,” Grunwald says, relying on taste and chemical signals.

Spotted salamander eggs and a marbled salamander larva, temporarily held in a plastic bag for viewing purposes.
Photo by Adam Kosinski, Wild Ones co-president.

Since marbled salamanders laid their eggs last fall, their larvae have had time to hatch and start developing, though they aren’t yet adults. Spotted salamanders, meanwhile, don’t breed until spring—when the ponds actually exist—so their eggs haven’t yet hatched. For the larvae of both species, developing in small, temporary ponds helps protect them from large predators like fish.

Both marbled and spotted salamanders are in a genus sometimes called mole salamanders because they live underground when they’re not breeding. “There’s an entire city underground here of burrows and holes and crevices,” Grunwald says, a “whole porous network of spaces.” The mole salamanders can shelter underground, but they can’t travel far without coming back to the surface. “It’s not a highway,” Grunwald says.

I would like to know what it is like to be a mole salamander, navigating by taste and smell and spending much of the year in small spaces underground.

Sam, a Wild Ones member, releasing the eggs back into the pond.

Before we left the forest, we went searching for lycophytes, an ancient lineage of plants that first evolved hundreds of millions of years ago. “In the Carboniferous Period 350 million years ago, these guys ruled,” Manos says. The lycophytes we saw in the Duke Forest were tiny, bright green sprigs in a small stream, but their ancestors were trees. Those ancient lycophyte trees are “responsible for all of the coal that we use,” says Manos. “The transformation of their organic material via millions of years of heat and pressure to metamorphic carbonized rock is the definition of coal.”

Quillwort, a modern-day descendant of ancient trees.

The lycophytes in the stream are members of the Isoetes genus, also known as quillworts. They look and feel much like grasses, but they are only distant relatives of true grasses. Grasses are flowering plants, while quillworts are lycophytes. Flowering plants and lycophytes diverged hundreds of millions of years ago. Lycophytes use spores to reproduce and have a life cycle similar to ferns. Even their leaves are anatomically and evolutionarily different from the leaves of flowering plants; lycophytes use “their own approach to making leaves,” according to Manos.

A representation of the evolutionary history of plants. Lycophytes, including the superficially grass-like quillwort we saw, are in the pteridophyte group, along with ferns. True grasses, on the other hand, are monocots, a branch of flowering plants.
Plant phylogeny.png, from Maulucioni via Wikimedia Commons, is licensed under the Creative Commons Attribution-Share Alike 4.0 International license.

Post by Sophie Cox, Class of 2025

Warning: Birding Can Change You. Let It.

By Sophie Cox

On February 26, 2023

In Animals, Biology, Environment/Sustainability, Field Research, Science Communication & Education, Students

The Wild Ones, a student organization focused on enjoying and learning about nature, recently went to Flat River Waterfowl Compound to look for birds and my personal nemesis.

I have a nemesis (a bird that defies my searching). Actually, I have several, but I have been preoccupied with this particular nemesis for months.

I have seen an evening grosbeak exactly once, in a zoo, which emphatically does not count. For years, I have been fixated on-and-off (mostly on) with the possibility of seeing one in the wild.

Photo of a male evening grosbeak.
“Evening Grosbeak” by sedge23 is licensed under CC BY 2.0.

They have thick, conical beaks. The males are sunset-colored. (But good luck finding one at sunset, even though the first recorded sighting supposedly happened at twilight, hence their name.) I daydream about flocks of them descending on my bird feeders at home or wandering onto Duke’s campus. That hasn’t happened yet (unless it has happened while I have not been watching, an excruciating possibility I will simply have to live with).

Evening grosbeaks usually live in Canada and the northern U.S., but they are known to irrupt into areas farther south. Irruptions often occur in response to lower supplies of seeds and cones in a bird’s typical range, making it possible to predict bird irruptions, at least if you’re the famous finch forecaster. (Fun fact: “irrupt” literally means “break into,” whereas “erupt” means “break out.”)

Breaking news: The grosbeaks are in Durham, and they have been since December. I will wait while you perform any necessary reactions, including screaming, jumping up and down in delight, charging outside because you simply have to go find them right now, or telling me I must be mistaken.

I am not mistaken. There is a flock of evening grosbeaks overwintering at Flat River Impoundment, 11.8 miles from Duke University. I know this because I get hourly rare bird alerts by email, and I have been receiving emails about evening grosbeaks nearly every day for almost three months. Put another way, evening grosbeaks have been actively and no doubt intentionally taunting me for weeks on end.

Adam Kosinski, Wild Ones co-president, with binoculars.

Wild Ones, a student organization I’m involved with, had been thinking of organizing a birding trip. For reasons I will not even attempt to deny, I suggested Flat River Waterfowl Impoundment. Last Sunday, seven undergraduates drove there, armed with field guides and binoculars and visions of evening grosbeaks bursting into sight (okay, maybe that was just me).

Flat River Waterfowl Impoundment.
Photo by Adam Kosinski.

The morning was chilly but sunny. Flat River is a gorgeous, swampy place full of small ponds and stretches of long grass edged with trees. As soon as we got there, we were serenaded with birdsong: the high, musical trill of pine warblers, the haunting coo of mourning doves, lilting Carolina wren songs, and squeaky-dog-toy brown-headed nuthatch calls.

It wasn’t long before people got to experience the frustrating side of birding. We were admiring a sparrow in a ditch, trying to guess its identity. Someone pulled out a field guide and flipped through the sparrow section only to turn back to the bird and find it gone. Birds can fly. But fortunately, we’d collectively noticed enough field marks to feel reasonably confident identifying it as a swamp sparrow.

A white-throated sparrow, one of several that was feeding on the buds of this tree. Note the white throat and yellow lores.
Photo by Lydia Cox, Wild Ones member. (We are not related, if you’re wondering.)

We found two other sparrow species later: song sparrows and white-throated sparrows. Sparrows tend to be small, brownish, and streaky, but certain features can help distinguish some of the common species around here. I’m personally not very familiar with the swamp sparrow, but it has a rusty cap and gray face. The song sparrow has brown stripes on its head, extensive streaking on its underside, and a dark spot on its breast. The white-throated sparrow has striking black-and-white stripes on the top of its head, yellow lores on its face (the spot in front of the eye), and yes, a white throat. (Just don’t rely too much on bird names for identification. Red-bellied woodpeckers definitely have red heads but usually only have red bellies if you’re rather imaginative, but beware—they’re still red-bellied, not red-headed woodpeckers. Meanwhile, there are dozens of warblers with yellow on them, but only one of them is a yellow warbler. Nashville warblers only pass through Nashville during migration, and American robins aren’t robins at all.)

A Cooper’s hawk with prey between its talons. Note the gray wings, the red barring on the bird’s underside, the dark bands on its tail, and the red eye.
Photo by Lydia Cox.

We saw Carolina chickadees flitting through trees, an Eastern phoebe doing its characteristic tail-wagging, and a Cooper’s hawk feeding on prey. Then, thrillingly, we spotted a bald eagle soaring through the sky. The bald eagle, America’s national bird since 1782, was in danger of extinction for years, largely due to the insecticide DDT, which made their eggs so thin that even being incubated by their parents could make them crack. However, the bald eagle was removed from the endangered species list in 2007, and populations have continued to increase.

A bald eagle in flight.
Photo by Lydia Cox.

Not long after the eagle sighting, we saw another flying raptor: an osprey. In fact, it must have been a good day for raptors because by the end of our trip we had recorded one osprey, two Cooper’s hawks, three bald eagles, and two red-tailed hawks.

We also saw a lot of birders—perhaps two dozen others, maybe more, not counting our own group. Each time we passed a group going in the opposite direction, I asked them if they’d found the grosbeaks.

A bald eagle nest.
Photo taken with my phone through my binoculars, a technique that is slowly teaching me a modicum of patience.

I think everyone I asked had seen them, and they were all eager to point us in the right direction. Birders like to use landmarks like “by the eagles’ nest” and “the fifth pine on the right” and “past the crossbills.” We found the eagles’ nest, with help from some of the local birders. We think we found the fifth pine on the right, but there were a lot of pines there, so we’re not sure.

We did not find the red crossbills, another irruptive bird species overwintering here this year. (Crossbills are aptly named. The tips of their mandibles really do cross, which helps them access seeds inside cones.)

Red crossbills, another irruptive bird species, have also been overwintering at Flat River Waterfowl Impoundment, but Wild Ones did not see them.
“Red Crossbills (Male)” by Elaine R. Wilson, www.naturespicsonline.com is licensed under CC BY-SA 3.0.

We found the spot where the evening grosbeaks had most recently been seen — just twenty minutes before we got there, according to the people we were talking to. We waited. We scrutinized the pine trees. We watched red-tailed hawks and bald eagles circle high above us. We admired the eagles’ nest, a huge collection of sticks high in a pine tree.

Adam Kosinski and Abby Saks, making sure there were no birds hiding underwater. (They were actually looking at interesting water creatures like crayfish and tadpoles.)

Would you like to guess what we did not find? My nemesis. Because the evening grosbeaks have devious minds and clearly flew all the way to Durham with the sole intent of hiding from me, dodging me, flying away as soon as I approached, and flying back again as soon as I was gone. (No, really. Other people reported them at Flat River that same day, both before and after our trip there.)

From left: Ethan Rehder, Barron Brothers, Sophie Cox, Gurnoor Majhail (Wild Ones co-president), and Lydia Cox.
Photo by Adam Kosinski.

Birding can be intensely frustrating. It can plant images in your mind that will haunt you and taunt you for the rest of your life. Like, for instance, the tiny blue bird I caught a brief glimpse of in the trees one early morning in Yellowstone. For years, I wondered if it could have been a cerulean warbler, but cerulean warblers don’t live in the western U.S. Or let’s talk about the green bird—yes, I swear it was green; no, I can’t prove it—that came to my bird feeders several years ago and never came back. Not while I was watching, anyway. The only thing I can think of for that one is a female painted bunting, but painted buntings aren’t usually in upstate South Carolina. (If my local volunteer eBird reviewer in South Carolina ever happens to read this, I promise I won’t report either of those mystery sightings to eBird.) Or, of course, the evening grosbeaks that flew away twenty minutes before we arrived.

Birding can also be thrilling, meditative, and by all accounts wonderful. Yes, that little blue bird in Yellowstone and the maybe-green one in my backyard are branded in my memory, as are countless more moments of maybe and almost and what if? I will never know what they were. I will probably never get over it.

But there are other moments that stick in my mind just as clearly. The bald eagle soaring above us on this Wild Ones trip. The black-capped chickadee that landed on my finger years ago while my brother and I rested our hands on a bird feeder and waited to see what would happen. My first glimpse of a black-throated blue warbler (I am so proud of whoever named that bird species), chasing an equally tiny Carolina chickadee in my backyard.

Warbler illustrations by James Ellsworth De Kay, a zoologist who described hundreds of animal species in the 19th century. From top to bottom: black-throated blue warbler, Cape May warbler, and Nashville warbler.
“131. The Black-throated Blue Warbler (Sylvicola canadensis) 132. He Cape-May Warbler (Sylvicola maritima) 133. The Nashville Warbler (Syvicola ruficapilla) illustration from Zoology of New york (1842 – 1844) by James Ellsworth De Kay (1792-1851).” by Free Public Domain Illustrations by rawpixel is licensed under CC BY 2.0.

The Cape May warbler I saw with a close friend in a small field covered in purple wildflowers. The first time I heard the loud, ringing Teacher-teacher-teacher! song of the ovenbird. A blackpoll warbler, the first I’d ever seen, in a grove of trees in a swampy field that only birders seem to find reason to visit.

The moment two Carolina wrens took food from my hand for the first time. Prothonotary warblers (another nemesis bird) practically dripping from the trees on a rainy, buggy hike along a boardwalk. The downy woodpecker that landed on my gloved hand, apparently too impatient to wait for me to finish what I was doing with the suet feeder, and pecked at the suet with that sharp beak, her black tongue flicking in and out, her talons clinging to me with a trust that brought tears to my eyes.

Birding can change you. It can make your world come alive in a whole new way. It can make traveling somewhere new feel all the more magical — a new soundscape, new flashes of colors and patterns, a new set of beings that make a place what it is. In the same way, birding can make home feel all the more like home. Even when I can’t name all the birds that are making noise in my yard, there is a familiarity to their collective symphony, a comforting sense of “You are here.” I encourage you to watch and listen to birds, too, to join the quasi-cult that birding can be, to trek through somewhere wet and dark when the sky is just beginning to lighten—or to simply step outside, wherever you are, and listen and watch and wait right here and right now. You don’t even need to know their names (though once you start, good luck stopping). And you certainly don’t need a nemesis bird. In fact, your birding experience will be calmer without one. But that might not be up to you, in the end. Nemesis birds have minds of their own.

Post by Sophie Cox, Class of 2025

Recovery, Resilience, and Coexistence: Nature-based Solutions on the Coast

By Sophie Cox

On February 10, 2023

In Animals, Biology, Climate/Global Change, Environment/Sustainability, Faculty, Field Research, Lecture, Oceans, Policy

When it comes to balancing the needs of humans and the needs of nature, “Historically it was ‘develop or conserve’ or ‘develop or restore,’” says Carter Smith, Ph.D., a Lecturing Fellow in the Division of Marine Science & Conservation who researches coastal restoration.

However, according to Brian Silliman, Ph.D., Rachel Carson Distinguished Professor of Marine Conservation Biology, “We are having a new paradigm shift where it’s not just… ‘nature over here’ and ‘humans over here.’”

Instead, conservation initiatives are increasingly focusing on coexistence with nature and ecological resilience, according to this panel discussion of marine science experts during Duke Research and Innovation Week 2023.

Nature-based solutions — protecting and restoring natural shoreline habitats — have a proven role in protecting and restoring coastal ecosystems. According to the International Union for Conservation of Nature (IUCN), “Nature-based solutions… address societal challenges effectively and adaptively, simultaneously benefiting people and nature.”

The panel, moderated by Andrew J. Read, Ph.D., Stephen A. Toth Distinguished Professor of Marine Biology and Professor of Marine Conservation Biology, also included Brian Silliman, Carter Smith, and Stephanie Valdez, a Ph.D. Student in Marine Science & Conservation.

Living shorelines can help protect coastal ecosystems from storms while also offering benefits for climate and conservation. Photos by Carter Smith.

According to Smith, nature-based solutions can “leverage nature and the power of healthy ecosystems to protect people” while also preserving biodiversity and mitigating climate change. She spoke about living shorelines as an effective and ecologically responsible way to protect coastal ecosystems.

“The traditional paradigm in coastal protection is that you build some kind of hard, fixed structure” like a seawall, Smith said, but conventional seawalls can have negative effects on biodiversity, habitats, nutrient cycling, and the environment at large. “In this case, coastal protection and biodiversity really are at odds.”

After multiple hurricanes, living shorelines had significantly less visible damage or erosion than sites with conventional hardscape protection, like seawalls.
Nicholas Lecturing Fellow Carter Smith

That’s where living shorelines come in. Living shorelines incorporate plants and natural materials like sand and rock to stabilize coastal areas and protect them from storms while also creating more natural habitats and minimizing environmental destruction. But “if these structures are actually going to replace conventional infrastructure,” Smith says, it’s important to show that they’re effective.

Smith and colleagues have studied how living shorelines fared during multiple hurricanes and have found that living shorelines had significantly less “visible damage or erosion” compared to sites with conventional storm protection infrastructure.

After Hurricane Matthew in 2016, for instance, both natural marshes and conventional infrastructure (like seawalls) lost elevation due to the storm. Living shorelines, on the other hand, experienced almost no change in elevation.

Smith is also investigating how living shorelines may support “community and psychosocial resilience” along with their benefits to biodiversity and climate. She envisions future community fishing days or birdwatching trips to bring people together, encourage environmental education, and foster a sense of place.

PhD student Stephanie Valdez then spoke about the importance of coastal ecosystems.

“Blue carbon ecosystems,” which include sea grasses, marshes, and mangroves, provide services like stabilizing sediments, reducing the destructive force of powerful waves, and storing carbon, she said. These ecosystems can bury carbon much faster than terrestrial ecosystems, which has important implications when it comes to climate change.

In the atmosphere, carbon dioxide and other greenhouse gasses contribute to global warming, but plants pull carbon dioxide out of the air during photosynthesis and convert it to carbohydrates, releasing oxygen as a byproduct. Therefore, ecosystems rich in fast-growing plants can serve as carbon sinks, reducing the amount of atmospheric carbon, Valdez explained.

Unfortunately, blue carbon ecosystems have suffered significant loss from human activities and development. We’ve replaced these wild areas with farms and buildings, polluted them with toxins and waste, and decimated habitats that so many other creatures rely on. But given the chance, these places can sometimes grow back. Valdez discussed a 2013 study which found that seagrass restoration led to a significantly higher carbon burial rate within just a few years.

Sea grasses, marshes, and mangroves provide services like stabilizing sediments, reducing the destructive force of powerful waves, and storing carbon.
PhD Student Stephanie Valde

Valdez also talked about the importance of recognizing and encouraging natural ecological partnerships within and between species. Humans have taken advantage of such partnerships before, she says. Consider the “Three Sisters:” beans, corn, and squash, which Native Americans planted close proximity so the three crops would benefit each other. Large squash leaves could provide shade to young seedlings, beans added nitrogen to the soil, and cornstalks served as a natural beanpole.

Recognizing that mutualistic relationships exist in natural ecosystems can help us preserve habitats like salt marshes. Valdez points to studies showing that the presence of oysters and clams can positively impact seagrasses and marshes. In restoration, it’s important “that we’re not focusing on one species alone but looking at the ecosystem as a whole”—from top predators to “foundation species.”

“There is hope for successful restoration of these vital ecosystems and their potential to aid in climate change mitigation,” Valdez said.

Finally, Prof. Brian Silliman discussed the role of predators in wider ecosystem restoration projects. Prioritizing the protection, restoration, and sometimes reintroduction of top predators isn’t always popular, but Silliman says predators play important roles in ecosystems around the world.

“One of the best examples we have of top predators facilitating ecosystems and climate change mitigation are tiger sharks in Australia,” he says. When the sharks are around, sea turtles eat fewer aquatic plants. “Not because [the sharks] eat a lot of sea turtles but because they scare them toward the shoreline,” reducing herbivory.

However, Silliman said it’s unclear sometimes whether the existence of a predator is actually responsible for a given benefit. Other times, though, experiments provide evidence that predators really are making a difference. Silliman referenced a study showing that sea otters can help protect plants, like seagrasses, in their habitats.

Restoring or reintroducing top predators in their natural habitats can help stabilize ecosystems impacted by climate change and other stressors.

And crucially, “Predators increase stress resistance.” When physical stressors reach a certain point in a given ecosystem, wildlife can rapidly decline. But wildlife that’s used to coexisting with a top predator may have a higher stress threshold. In our ever-changing world, the ability to adapt is as important as ever.

“I think there is great optimism and opportunity here,” Silliman says. The other speakers agree. “Right now,” Valdez says, “as far as restoration and protection goes, we are at the very beginnings. We’re just at the forefront of figuring out how to restore feasibly and at a level of success that makes it worth our time.”

Restoring or reintroducing top predators in their natural habitats can help stabilize ecosystems impacted by climate change and other stressors.
Brian Silliman

Smith emphasized the important role that nature-based solutions can play. Even in areas where we aren’t achieving the “full benefit of conserving or restoring a habitat,” we can still get “some benefit in areas where if we don’t use nature-based solutions,” conservation and restoration might not take place at all.

According to Valdez, “Previously we would see restoration or… conservation really at odds with academia itself as well as the community as a whole.” But we’re reaching a point where “People know what restoration is. People know what these habitats are. And I feel like twenty or thirty years ago that was not the case.” She sees “a lot of hope in what we are doing, a lot of hope in what is coming.”

“There’s so much that we can learn from nature… and these processes and functions that have evolved over millions and millions of years,” Smith adds. “The more we can learn to coexist and to integrate our society with thriving ecosystems, the better it will be for everyone.”

Post by Sophie Cox, Class of 2025

Traveling With Friends Helps Even Mixed-Up Migrators Find Their Way

By Robin Smith

On December 6, 2022

In Animals, Behavior/Psychology, Biology, Climate/Global Change

North American monarch butterflies migrate each winter to just a few mountaintops in central Mexico, with help from an internal compass that guides them home. New computer modeling research offers clues to how migrating animals get to where they need to go, even when their magnetic compass leads them astray. Credit: Jesse Granger, Duke University

DURHAM, N.C. — Some of us live and die by our phone’s GPS. But if we can’t get a signal or lose battery power, we get lost on our way to the grocery store.

Yet animals can find their way across vast distances with amazing accuracy.

Take monarch butterflies, for example. Millions of them fly up to 2,500 miles across the eastern half of North America to the same overwintering grounds each year, using the Earth’s magnetic field to help them reach a small region in central Mexico that’s about the size of Disney World.

Or sockeye salmon: starting out in the open ocean they head home each year to spawn. Using geomagnetic cues they manage to identify their home stream from among thousands of possibilities, often returning to within feet of their birthplace.

Now, new research offers clues to how migrating animals get to where they need to go, even when they lose the signal or their inner compass leads them astray. The key, said Duke Ph.D. student Jesse Granger: “they can get there faster and more efficiently if they travel with a friend.”

When their internal compasses go bad, migrating animals like these sockeye salmon don’t stop to ask directions. But they succeed if they stay with their fellow travelers. Credit: Jonny Armstrong, USGS

Many animals can sense the Earth’s magnetic field and use it as a compass. What has puzzled scientists, Granger said, is the magnetic sense is not fail-safe. These signals coming from the planet’s molten core are subtle at the surface. Phenomena such as solar storms and man-made electromagnetic noise can disrupt them or drown them out.

It’s as if the ‘needle’ of their inner compass sometimes gets thrown off or points in random directions, making it hard to get a reliable reading. How do some animals manage to chart a course with such a noisy sensory system and still get it right?

“This is the question that keeps me up at night,” said Granger, who did the work with her adviser, Duke Biology Professor Sönke Johnsen.

Multiple hypotheses have been put forward to explain how they do it. Perhaps, some scientists say, migrating animals average multiple measurements taken over time to get more accurate information.

Or maybe they switch from consulting their magnetic compass to using other ways of navigating as they near the end of their journey — such as smell, or landmarks — to narrow in on their goal.

In a paper published Nov. 16 in the journal Proceedings of the Royal Society B, the Duke team wanted to pit these ideas against a third possibility: That some animals still manage to find their way, even when their compass readings are unreliable, simply by sticking together.

To test the idea, they created a computer model to simulate virtual groups of migrating animals, and analyzed how different navigation tactics affected their performance.

The animals in the model begin their journey spread out over a wide area, encountering others along the route. The direction an animal takes at each step along the way is a balance between two competing impulses: to band together and stay with the group, or to head towards a specific destination, but with some degree of error in finding their bearings.

The scientists found that, even when the simulated animals started to make more mistakes in reading their magnetic map, the ones that stuck with their neighbors still reached their destination, whereas those that didn’t care about staying together didn’t make it.

“We showed that animals are better at navigating in a group than they are at navigating alone,” Granger said.

Even when their magnetic compass veered them off course, more than 70% of animals in the model still made it home, simply by joining with others and following their lead. Other ways of compensating didn’t measure up, or would need to guide them perfectly for most of the journey to accomplish the same feat.

But the strategy breaks down when species decline in number, the researchers found. The team showed that animals who need friends to find their way are more likely to get lost when their population shrinks below a certain density.

Prior to the 1950s, tens of thousands of Kemp’s ridley sea turtles could be seen nesting near Rancho Nuevo, Mexico on a single day. By the mid-1980s the number of nesting females had dropped to a few hundred.

“If the population density starts dropping, it takes them longer and longer along their migratory route before they find anyone else,” Granger said.

Previous studies have made similar predictions, but the Duke team’s model could help future researchers quantify the effect for different species. In some runs of the model, for example, they found that if a hypothetical population dropped by 50% — akin to what monarchs have experienced in the last decade, and some salmon in the last century — 37% fewer of the remaining individuals would make it to their destination.

“This may be an underappreciated aspect of concern when studying population loss,” Granger said.

This research was supported in part by the Air Force Office of Scientific Research (FA9550-20-1-0399) and by a National Defense Science & Engineering Graduate Fellowship to Jesse Granger.

CITATION: “Collective Movement as a Solution to Noisy Navigation and its Vulnerability to Population Loss,” Jesse Granger and Sönke Johnsen. Proceedings of the Royal Society B, Nov. 16, 2022. DOI: 10.1098/rspb.2022.1910

COVID and Our Education

By Jakaiyah Franklin

On November 28, 2022

In Biology, Global Health, Lecture, Science Communication & Education

With mask mandates being overturned and numerous places going back to “normal,” COVID is becoming more of a subconscious thought. Now, this is not a true statement for the entire population, since there are people who are looking at the effects of the pandemic and the virus itself.

I attended a poster presentation for the “The Pandemic Divide” event hosted here at Duke by the Samuel Dubois Cook Center on Social Equity. To me, all the poster boards conveyed the theme of how COVID-19 had affected our lives in more ways than just our health. One connection that particularly caught my eye would be the one between American Education and COVID.

As a student who lived through COVID while attending high school, I can safely say that the pandemic has affected education. However, based on the posters I saw, it is important to know that education, too, has a strong and impactful impact on COVID-19.

Dr. Donald J. Alcendor after a great presentation

The first evidence I saw was from Donald J. Alcendor, an associate professor of microbiology and immunology at Meharry Medical College in Nashville. His poster was about the hesitancy surrounding COVID-19 vaccines. One way he and his team figured out to lessen the hesitance from the public was to improve the public’s trust. To achieve this, Alcendor and his team sent trusted messengers into the community. One of the types of messengers they provided was scientists who studied COVID-19. These scientists were able to bring factual information about the disease, how it spreads, and the best course of action to act against it. Alcendor and his research team also brought in “vaccine ambassadors” to the community and a mobile unit to help give the community vaccines. He noted that this was accomplished with support from the Bloomberg Foundation’s Greenwood Initiative, which addresses Black health issues.

With this mobile unit, Alcendor and his team were able to reach people and help those who were otherwise unable to receive help for themselves because of their lack of transportation. They provided people from all backgrounds with help and valuable information.

Alcindor said he and his team planned pop-up events based on where the community they were trying to reach congregates. With the African American community, he planned pop-up events at churches and schools. Then for the Latino community, he planned pop-events where families tend to gather, and he held events in Latin0 neighborhoods. In addition, he made sure that the information was available in Spanish at all levels, from the flyers and the surveys, to the vaccinators themselves.

All of these amenities that he and his group provided were able to educate the community about COVID-19 and improve their trust in the scientists working on the disease. Alcendor and his team were able to impact COVID-19 through education, and by going to the event, it was evident to me that he was not the only one who accomplished this.

Colin Cannonier, an associate professor of economics at Belmont University in Nashville, asked and answered the question, “does education have an impact on COVID? Specifically, does it change health and wellbeing?” To answer this question, he researched how education about COVID can affect a person. He discovered that when a person is more educated about COVID, how it is spread, and its symptoms, they are more likely to keep the pandemic in check through their behavior. He came to this conclusion because he realized that when higher educated people know more about COVID, they exhibit behaviors to remain healthy, meaning that they would follow the health protocols given by the health officials.

While this may seem like common sense that the more educated a person is, the more they make smart choices pertaining to COVID, this shows how important education is and how deadly ignorance is. Cannonier’s research gave tangible evidence to show that education is a weapon against diseases. Unfortunately, it is evident that some officials did not believe in educating the public about the virus or the virus itself, and that proved to be extremely deadly.

To fully capture the relationship between COVID and education, one must also talk about how COVID-19 affected education.

Ms. Stacey Akines and her wonderful poster

Stacey Akines, a history graduate student at Carnegie Mellon University, studied how education was changed by the pandemic.

First, she realized that COVID schooling crossed over with homeschooling. Then she uncovered that more Black people started to research and teach their children about Black history. This desire to teach youth more about their history caused an increase in the number of Black homeschoolers. In fact, the number of Black homeschoolers doubled during the fall of 2020. While to some, this change to homeschooling may have a negative impact on one’s life, it actually gives the student more opportunities to learn things.

It is no secret that there are many books being banned here in the U.S., and there are many state curriculums that are changing to erase much of Black history. Homeschooling a child gives the parent an opportunity to ensure that the education they receive is true to and tells their history

Unlike me, where during high school, education felt lackluster and limited because of COVID, some parents saw an opportunity to better their child’s education.

I hope that it is clear that the relationship between COVID and education is a complex one. Both can greatly impact each other, whether it’s for the better or for the worse. COVID thrives when we are uneducated, and it very nearly destroyed education too, but for the efforts of some dedicated educators.

Post by Jakaiyah Franklin, Class of 2025

Why Do Some Dogs Need High Chairs, and How Can Genetics Help?

By Sophie Cox

On November 17, 2022

In Animals, Biology, Genetics/Genomics, Lecture, Medicine

Jake, a German shepherd dog in a Bailey chair. Dogs with megaesophagus must eat in a vertical position to help food travel to their stomachs.
Photo credit: Beth Grant

Some dogs have to eat in a high chair—or, more specifically, a Bailey Chair. The chair keeps them in a vertical position while they eat so that gravity can do the work their bodies can’t: moving food from the mouth to the stomach.

These dogs have megaesophagus, an esophagus disorder that can prevent dogs from properly digesting food and absorbing nutrients. When you swallow a bite of food, it travels down a muscular tube, the esophagus, to the stomach. In humans, the esophagus is vertical, so our esophageal muscles don’t have to fight against gravity. But because dogs are quadrupeds, a dog’s esophagus is more horizontal, so “there is a greater burden on peristaltic contractions to transport the food into the stomach.” In dogs with megaesophagus, the esophagus is dilated, and those contractions are less effective. Instead of moving properly into the stomach, food can remain in the esophagus, exacerbating the problem and preventing proper digestion and nutrient absorption.

Leigh Anne Clark, Ph.D., an associate professor at Clemson University, recently spoke at Duke about megaesophagus in dogs and its genetic underpinnings. She has authored dozens of publications on dog genetics, including five cover features. Her research primarily involves “[mapping] alleles and genes that underlie disease in dogs.” In complex diseases like megaesophagus, that’s easier said than done. “This disease has a spectrum,” Clark says, and “Spoiler: that makes it more complicated to map.”

Clinical signs of megaesophagus, or mega for short, include regurgitation, coughing, loss of appetite, and weight loss. (We might use the word “symptom” to talk about human conditions, but “a symptom is something someone describes—e.g., I feel nauseous. But dogs can’t talk, so we can only see ‘clinical signs.’”) Complications of mega can include aspiration pneumonia and, in severe cases, gastroesophageal intussusception, an emergency situation in which dogs “suck their stomach up into their esophagus.”

Sometimes megaesophagus resolves on its own with age, but when it doesn’t it requires lifelong management. Mega has no cure, but management can involve vertical feeding, smaller and more frequent meals, soft foods, and sometimes medication. Even liquid water can cause problems, so some dogs with mega receive “cubed water,” made by adding a “gelatinous material” to water, instead of a normal water bowl.

In dogs, mega can be either congenital, meaning present at birth, or acquired. In cases of acquired megaesophagus, the condition is “usually secondary to something else,” and the root cause is often never determined. (Humans can get mega, too, but as with acquired mega in dogs, mega in humans is usually caused by a preexisting condition. The best human comparison, according to Clark, might be achalasia, a rare disorder that causes difficulty swallowing.) Clark’s current research focuses on the congenital form of the disease in dogs.

Her laboratory recently published a paper investigating the genetic foundation of mega. Unlike some diseases, mega isn’t caused by just one genetic mutation, so determining what genes might be at play required some genetic detective work. “You see mega across breeds,” Clark says, which suggests an environmental component, but the disease is more prevalent in some breeds than others. For instance, 28 percent of all diagnoses are in German shepherds. That was a “red flag” indicating that genes were at least partly responsible.

Clark and her collaborators chose to limit their research study to German shepherds. Despite including a wide range of dogs in the study, they noticed that males were significantly overrepresented. Clark thinks that estrogen, a hormone more abundant in females, may have a protective effect against mega.

Clark and her team performed a genome-wide association study (GWAS) to look for alleles that are more common in dogs with mega. One allele that turned out to be a major risk factor was a variant of the MCHR2 gene, which plays a role in feeding behaviors. In breeds where mega is overrepresented, like German shepherds, “we have a situation where the predominant allele in the population is also the risk allele,” says Clark.

Using the results of the study, they developed a test that can identify which version of the gene a given dog has. The test, available at veterinary testing companies, is designed “to help breeders reduce the frequency of the risk allele and to plan matings that are less likely to produce affected puppies.”

Duke’s Most-Cited — The Scholars Other Scientists Look To

By Karl Bates

On November 15, 2022

In Behavior/Psychology, Biology, Chemistry, Faculty, Immunology, Medicine, Nanotech, Neuroscience

It’s not enough to just publish a great scientific paper.

Somebody else has to think it’s great too and include the work in the references at the end of their paper, the citations. The more citations a paper gets, presumably the more important and influential it is. That’s how science works — you know, the whole standing-on-the-shoulders-of-giants thing.

So it always comes as a chest swelling affirmation for Dukies when we read all those Duke names on the annual list of Most Cited Scientists, compiled by the folks at Clarivate.

This year is another great haul for our thought-leaders. Duke has 30 scientists among the nearly 7,000 authors on the global list, meaning their work is among the top 1 percent of citations by scientific field and year, according to Clarivate’s Web of Science citation index.

As befits Duke’s culture of mixing and matching the sciences in bold new ways, most of the highly cited are from “cross-field” work.

Duke’s Most Cited Are:

Biology and Biochemistry

Charles A. Gersbach

Robert J. Lefkowitz

Clinical Medicine

Scott Antonia

Christopher Bull Granger

Pamela S. Douglas

Adrian F. Hernandez

Manesh R. Patel

Eric D. Peterson

Cross-Field

Chris Beyrer

Stefano Curtarolo

Renate Houts

Tony Jun Huang

Ru-Rong Ji

Jie Liu

Jason Locasale

Edward A. Miao

David B. Mitzi

Christopher B. Newgard

John F. Rawls

Drew T. Shindell

Pratiksha I. Thakore

Mark R. Wiesner

Microbiology

Barton F. Haynes

Neuroscience and Behavior

Quinn T. Ostrom

Pharmacology and Toxicology

Evan D. Kharasch

Plant and Animal Science

Xinnian Dong

Sheng Yang He

Psychiatry and Psychology

Avshalom Caspi

William E. Copeland

E. Jane Costello

Terrie E. Moffitt

Social Sciences

Michael J. Pencina

John W. Williams

Congratulations, one and all! You’ve done us proud again.

“Of Sound Mind”: a Discussion of the Hearing Brain

By Sophie Cox

On October 18, 2022

In Behavior/Psychology, Biology, Computers/Technology, Lecture, Neuroscience, Science Communication & Education

“To me [this image] captures the wonder, the awe, the beauty of sound and the brain that tries to make sense of it,” said professor Nina Kraus, Northwestern University researcher and author of “Of Sound Mind: How Our Brain Constructs a Meaningful Sonic World.”

Stop. What do you hear?

We might not always think about the sounds around us, but our brains are always listening, said Northwestern University professor Nina Kraus.

Kraus, auditory researcher and author of “Of Sound Mind: How Our Brain Constructs a Meaningful Sonic World,” spoke via Zoom to a Duke audience in October. She has published more than four hundred papers on the auditory system in humans and other animals and how it’s affected by conditions like autism, aging, and concussion. She discussed some of her findings and how “the sound mind” affects us in our day-to-day lives.

One of the slides from Kraus’s presentation. We can think of sound as having many “ingredients.”

“I think of the sound mind as encompassing how we think, how we move, how we sense, and how we feel,” Kraus said. We live in a “visually dominated world,” but for hearing people, sound plays an important role in language, music, rhythm, and how we perceive the world.

One of the slides from Kraus’s presentation. The human auditory system involves not just the ears but also several regions of the brain. The “hearing brain” engages movement, cognition, and emotions along with interpreting direct sensory input from all senses.

Kraus discussed the auditory system and how much of what we think of as hearing takes place in the brain. We can think of sound as signals outside the head and electricity as signals inside the head (neural processing). When those two merge, learning occurs, and we can make sound-to-meaning connections.

Another slide from Kraus’s presentation. In an experiment, teaching rabbits to associate a sound with meaning (in this case, more carrots) changed patterns of neuron firing in the auditory cortex, even in individual neurons. “Same sound, same neuron, and yet the neuron responded differently… because now there’s a sound-to-meaning connection,” Kraus said.

Despite how sensitive our neurons and brains are to sound, things can get lost in translation. Kraus studies how conditions like concussions and hearing loss can adversely affect auditory processing. Even among healthy brains, we all hear and interpret sounds differently. People have unique “sonic fingerprints” that are relatively stable over time within an individual brain but differ between people. These patterns of sound recognition are apparent when scientists record brain responses to music or other sounds.

“One of the biological measures that we have been using in human and in animal models,” Kraus said, is FFR (frequency following response) to speech. FFR-to-speech can be used to analyze an individual’s auditory processing system. It also allows scientists to convert brain responses back into sound waves. “The sound wave and the brainwave resemble each other, which is just remarkable.”

One of Kraus’s slides. Technology called frequency following response (FFR) can be used to convert brain waves back into original sound (like a song).

This technology helps reveal just how attuned our brains are to sound. When we hear a song, our brain waves respond to everything from the beat to the melody. Those brain waves are so specific to that particular song or sound that when scientists convert the brain waves back into sound, the resulting music is still recognizable.

When scientists try this on people who have experienced a concussion, for instance, the recreated music can sound different or garbled. Experiments that compare healthy and unhealthy brains can help reveal what concussions do to the brain and our ability to interpret sound. But not everything that affects auditory processing is bad.

Musical training is famously good for the brain, and experiments done by Kraus and other scientists support that conclusion. “The musician signature—something that develops over time—” has specific patterns, and it can enhance certain components of auditory processing over time. Making music might also improve language skills. “The music and language signatures really overlap,” Kraus said, “which is why making music is so good for strengthening our sound mind.” Kids who can synchronize to a beat, for example, tend to have better language skills according to some of the experiments Kraus has been involved with.

Musicians are also, on average, better at processing sound in noisy environments. Musicians respond well in quiet and noisy environments. Non-musicians, on the other hand, respond well in quiet environments, but that response “really breaks down” in noisy ones.

Interestingly, “Making music has a lifelong impact. Making music in early life can strengthen the sound mind when one is seventy or eighty years old.”

A slide from Kraus’s presentation. Musicians tend to be better at processing sounds in noisy environments.

Exercise, too, can improve auditory processing. “Elite division 1 athletes have especially quiet brains” with less neural noise. That’s a good thing; it lets incoming information “stand out more.”

In experiments, healthy athletes also have a more consistent response over time across multiple trials, especially women.

These benefits aren’t limited to elite athletes, though. According to Kraus, “Being fit and flexible is one of the best things you can do for your brain,” Kraus said.

Kraus and her team have a regularly updated website about their work. For those who want to learn more about their research, they have a short video about their research approach and an online lecture Kraus gave with the Kennedy Center.

Nina Kraus with a piano. “Science is a deeply human endeavor,” she said, “and I think we often forget that. It’s made by people.”
Photo courtesy of Kraus and colleague Jenna Cunningham, Ph.D.

The Need for Title IX in STEM

By Jakaiyah Franklin

On October 10, 2022

In Behavior/Psychology, Biology, Biomedical Engineering, Engineering, Faculty, Science Communication & Education, Statistics, Students

The Panel:

In recognition of the 50th anniversary of Title IX, which was intended to make sex discrimination in education illegal, a panel of Duke women met on Thursday, September 29 to talk about whether Title IX could change STEM, (Science Technology, Engineering and Math). Unfortunately, the answer was not simple.

But just through the sharing of the statistics relevant to this problem, the stories, and their solutions, one could start to understand the depth of this problem. One takeaway was that all women in STEM, whether they be student, professor, or director, have faced gender discrimination.

The student panelists after a successful forum

Down to the Statistics:

Dr. Sherryl Broverman, a Duke professor of the practice in biology and global health, gave the audience an overview. Of all of Duke’s regular ranked, tenured-track faculty, only 30% are women. In contrast, women make up 60% of the non-tenure track faculty. Dr. Broverman said men are promoted in Duke at a higher frequency. This is especially seen with the associate professor title because, on average, men are associate professors for 4 to 5 years; whereas women are associate professors for up to 9 years.

To give an example, senior Nasya Bernard-Lucien, a student panelist who studied Biomedical Engineering and then Neuroscience informed me that she has had a total of two women professors in her entire STEM career. This is a common pattern here at Duke because taking a STEM class that has a woman professor is as rare as finding a non-stressed Duke student.

Dr. Kisha Daniels (left) and Dr. Whitney McCoy (right)

The Beginning of a Girl’s Career in STEM

This disproportionate demographic of women professors in STEM is not a new occurrence with Duke or the rest of the world because the disproportion of women in STEM can be seen as early as middle school. Two of the student panelists noted that during their middle school career, they were not chosen to join an honors STEM program and had to push their school’s administration when they asked to take more advanced STEM classes.

Dr. Kisha Daniels, an associate professor of the practice in education said on a faculty panel that one of her daughters was asked by her male peers, “what are you doing here?” when she attended her middle school’s honors math class. Gender discrimination in STEM begins in early childhood, and it extends its reach as long as women continue to be in a STEM field, and that is particularly evident here at Duke.

Women in STEM at Duke

The last panel of the Title IX @ 50 event was the student panel which consisted of undergraduate and graduate students. Even though they were all from different backgrounds, all acknowledged the gender disparity within STEM classes.

Student Bentley Choi said she was introduced to this experience of gender discrimination when she first arrived at Duke from South Korea. She noted how she was uncomfortable and how it was hard to ask for help while being one of the few women in her physics class. One would have hoped that Duke would provide a more welcoming environment to her, but that is not the case, and it is also not an isolated incident. Across the panel, all of the women have experienced discomfort in their STEM classes due to being one of the few girls in there.

The Future of Title IX

How can Title IX change these issues? Right now, Title IX and STEM are not as connected as they need to be; in fact, Title IX, in the past, has been used to attack programs created to remedy the gender disparity in STEM. So, before Title IX can change STEM, it needs to change itself.

Title IX needs to address that this problem is a systemic issue and not a standalone occurrence. However, for this change to happen, Dr. Whitney McCoy, a research scientist in Child and Family Policy, said it perfectly, “we need people of all backgrounds to voice the same opinion to create policy change.”

So, talk to your peers about this issue because the more people who understand this situation, the chances of creating a change increases. The last thing that needs to occur is that 50 years in the future, there will be similar panels like this one that talk about this very issue, and there are no panels that talk about how we, in the present, fixed it.

Post by Jakaiyah Franklin, Class of 2025

Do Snakes Have Tails? and Other Slithery Questions

By Sophie Cox

On September 28, 2022

In Animals, Biology, Climate/Global Change, Environment/Sustainability, Faculty, Field Research, Science Communication & Education, Students

Dhruv Rungta, a member of the Wild Ones club, with a ring-necked snake during a herpetology walk with Dr. Nicki Cagle in the Duke Forest.
Upper left: Dr. Nicki Cagle holding a ring-necked snake. Photo by Montana Lee, another Wild Ones member.

On a sunny Friday in September, Dr. Nicki Cagle led a herpetology walk in the Duke Forest with the Wild Ones. The Wild Ones is an undergraduate club focused on increasing appreciation for the natural world through professor-led outings. Herpetology is the study of reptiles and amphibians.

Dr. Cagle is a senior lecturer in the Nicholas School of the Environment at Duke and the Associate Dean of Diversity, Equity, and Inclusion. Along with teaching courses on environmental education and natural history, she is also the science advisor for a citizen science project focused on reptiles and amphibians, or herpetofauna, in the Duke Forest. Volunteers monitor predetermined sites in the Duke Forest and collect data on the reptiles and amphibians they find.

“We get a sense of abundance, seasonality… and how the landscape is affecting what we’re seeing,” Dr. Cagle says. There is evidence that herp populations in the Duke Forest and elsewhere are decreasing.

Dr. Nicki Cagle flipping over a cover board with members of the Wild Ones. The cover boards are used to monitor reptiles and amphibians for a citizen science project in the Duke Forest.

The project relies on transects, “a sampling design… where you have a sampling spot at various intervals” along a line of a predetermined length. In this case, the sampling spots are “traps” meant to attract reptiles and amphibians without harming them. Each site has a large board lying on the ground. “Different herps are more likely to be found under different objects,” Dr. Cagle explains, so the project uses both wooden and metal cover boards.

But why would snakes and other herps want to hide under cover boards, anyway? Reptiles and amphibians are “cold-blooded” animals, or ectotherms. They can’t regulate their own body temperature, so they have to rely on their environment for thermoregulation. Snakes might sun themselves on a rock on cold days, for instance, or hide under a conveniently placed wooden board to escape the heat.

Salamanders that use the cover boards might be attracted to the moist environment, while “snakes will tend to go under cover boards either to hide — like if they’re about to molt and they’re more vulnerable — to look for prey, or just to maintain the proper temperature,” Dr. Cagle says.

Citizen scientists typically check the boards once a week and not more than twice a week. Volunteers have to avoid checking the traps too often because of a phenomenon called “trap shyness,” where animals might start avoiding the traps because they’ve learned to associate them with pesky humans flipping the boards over and exposing their otherwise cozy resting places. By checking the traps less frequently, scientists can reduce the likelihood of that and minimize disturbance to the animals they’re studying.

The first snake we saw was a redbelly snake (*Storeria occipitomaculata*), dark above with a pink stomach.

Dr. Cagle gave the Wild Ones a behind-the-scenes tour of some of the cover boards. Using a special, hooked tool conveniently stashed in a PVC pipe next to the first cover board, we flipped each board over and looked carefully underneath it for slithery movements. We didn’t find any under the first several cover boards.

But then, under a large sheet of metal, we saw a tiny snake squirming around in the leaf litter. There was a collective intake of breath and exclamations of “snake!”

Dr. Cagle captured it and held it carefully in her hands. Snakes, especially snakes as young as this one, can be all too easily crushed. We gathered around to look more closely at the baby snake, a species with the adorable name “worm snake.” It was dark above with a strikingly pink underside. The pink belly is a key field mark of worm snakes. Earth snakes are also found around here and look similar, but they tend to have tan bellies.

After a minute or two, the worm snake made a successful bid for freedom and wriggled back under the board, disappearing from sight almost immediately.

Crossing over a dry “intermittent stream,” which Dr. Cagle describes as “the running-water equivalent of a vernal pool.” A vernal pool is a temporary wetland that is dry for much of the year.

Some of the cover boards revealed other animals as well. We found a caterpillar chrysalis attached to one and several holes — probably made by small mammals — under another.

Whatever made the holes, we can safely assume it wasn’t a snake. According to Dr. Cagle, the term “snakehole” is misleading. Most snakes don’t make their own holes, though some of them do use existing holes made by other animals. One exception is the bull snake, which is known for digging.

We found a young five-lined skink sunning itself on top of one of the metal cover boards. (Thermoregulation!) Juvenile five-lined skinks are colloquially known as blue-tailed skinks, but the name is somewhat misleading — the adults don’t have blue tails at all.

The snakes we were looking for, meanwhile, were often elusive. Some vanished under the leaf litter before we could catch them. Sometimes it was hard to tell whether we were even looking at a snake at all.

“What are you?” Dr. Cagle muttered at one point, crouching down to get a better look at what was either a stick-esque snake or a snake-esque stick. “Are you an animal? Or are you just a wet something?” (Just a wet something, it turned out.)

The Duke Forest is a valuable community resource with a complicated history. “We know that slavery was practiced on at least four properties” in the Duke Forest, Dr. Cagle says, and the forest is located on the traditional hunting grounds of several indigenous peoples. Today, the Duke Forest is used for research, recreation, timber management, and wildlife management and conservation.

Later on, we found at least three young ring-necked snakes (Diadophis punctatus) under different cover boards. One of them was particularly cooperative, so we passed it around the group. (“All snakes can bite,” Dr. Cagle reminded us, but “some have the tendency to bite less,” and this species “has the tendency not to bite.”) Its small, lithe body was surprisingly strong. The little snake wrapped tightly around one of my fingers and seemed content to chill there. A living, breathing, reptilian ring. That was definitely a highlight of my day.

The faint, dark line on this ring-necked snake’s underside (on the bottom of the loop) is the anal vent. Everything below that point (farther from the head) is considered the official tail of a snake.

If you’ve ever wondered if snakes have tails, the answer is yes. The official cut-off point, Dr. Cagle says, is the anal vent. Everything below that is tail. In between flipping over cover boards and admiring young snakes, we learned about other herps. Near the beginning of our walk, someone asked what the difference is between a newt and a salamander.

“A newt is a type of salamander,” Dr. Cagle says, “but newts have an unusual life cycle where they spend part of their life cycle on land… and that is called their eft phase.” As adults, they return to the water to breed.

We learned that copperheads “tend to be fatter-bodied for their length” and that spotted salamanders cross forest roads in large numbers on warm, rainy nights in early spring when they return to wetlands to breed.

Students holding a ring-necked snake. Above: Kelsey Goldwein (left), Gurnoor Majhail (one of the co-presidents of the Wild Ones), and Simran Sokhi (background on right). Below: Emily Courson (left) and Barron Brothers.

Perhaps the most interesting herp fact of the day came near the end of our walk when one of the students asked how you can tell the sex of a snake. Apparently there are two ways. You can measure a snake’s tail (males usually have longer tails), or you can insert a metal probe, blunted at the end, into a snake’s anal vent. Scientists can determine the sex of the snake by how deep the probe goes. It goes farther into the anal vent if the snake is a male. Why is that? Because male snakes have hemipenes — not two penises, exactly, but “an analogous structure that allows the probe to slide between the two and go farther” than it would in a female snake. The more you know…

Looking for snakes on a herpetology outing with Dr. Cagle and the Wild Ones. Photograph by Gurnoor Majhail.

Disclaimer: Handling wild snakes may result in snake bites. It can also be stressful to the snakes. Furthermore, some snakes in this area are venomous, and it’s probably best to familiarize yourself with those before getting close to snakes rather than afterward. Snakes are amazing, but please observe wildlife safely and responsibly.

Following the people and events that make up the research community at Duke

Category: Biology Page 1 of 29

Spongy Moss, Living Jelly, and Other Early Spring Delights

Warning: Birding Can Change You. Let It.

Recovery, Resilience, and Coexistence: Nature-based Solutions on the Coast

Traveling With Friends Helps Even Mixed-Up Migrators Find Their Way

COVID and Our Education

Why Do Some Dogs Need High Chairs, and How Can Genetics Help?

Duke’s Most-Cited — The Scholars Other Scientists Look To

“Of Sound Mind”: a Discussion of the Hearing Brain

The Need for Title IX in STEM

Do Snakes Have Tails? and Other Slithery Questions