Invasive Species - Biodiversity for a Livable Climate

Featured Creature: Burmese Python

Which creature is one of the largest snakes in the world, a popular exotic pet, and an unwanted addition to the Florida Everglades ecosystem?

One summer in high school, a close friend confessed that her parents had committed a crime when she was little. They released their two pet goldfish into a small pond behind her house to see what would happen. As far as experiments go, it was uneventful: the pair of fish grew to a respectable size, enough so that someone staring intently at the little pond could catch flashes of orange now and again. My friend’s goldfish fared well in her tiny pond, but could have also succeeded in a larger, more competitive environment. Goldfish thrive in most settings, so it is likely that they would outcompete native fish for food resources in the process of survival. However, the goldfish is not the only exotic pet with this potential. Governments around the world recognise this, which is why the release of pets into the wild is a legislated issue.

Many species can illustrate the need for these laws well, but one particularly dramatic story exists in the Florida Everglades: that of the Burmese python. What was once a popular pet has now become Florida’s nightmare, a situation so dire that massive swaths of Florida society have mobilized to hunt these former pets and their descendants en masse through the Everglades. While the Burmese Python has found a comfortable habitat in Florida, its tendency to eat everything in sight has made the state unable and unwilling to accommodate it.

Burmese Python Basics

The simplest way to understand what a Burmese python looks like? Ask a kindergartener to describe a snake. The Burmese python is a massive, formidable serpent. Although female Burmese pythons grow to larger sizes relative to their male counterparts, the average python commonly reaches lengths of 10-15 feet, but can grow over 20 feet and weigh in at 200 pounds. At this size, they can easily suffocate small mammals and other similar-sized prey.

The Burmese python is an r-selected species with reproductive traits ideal for turbulent situations. The Burmese python reaches reproductive age between four and five years old and can reproduce throughout its life. The average Burmese python lives to be 15-30 years old, depending on if it’s in the wild or captivity, and reproduces once per year. One clutch of eggs can be anywhere between 50 and 100 individuals. The average clutch has only a 38% survival rate, but this is all part of the snake’s plan of quantity over quality of maternal care. This reproduction strategy, combined with the python’s unfussy diet, allow it to adapt to new environments, and even outcompete native species for food and resources to the detriment of the ecosystem’s health: the definition of an invasive species.

Burmese Python’s native range in Asia.
Courtesy Animalia.

Burmese pythons exist in a variety of settings with varying degrees of success. Firstly, they often exist in captivity as a lucrative part of the exotic pet trade.
The python is an apex predator in the wild, and the only notable threats adult members of the population face are from humans, namely, poaching and industrial development. These issues are most prevalent in certain areas in the Burmese Python’s native range in Southeast Asia. In some zones, populations have declined by 80% in a single decade. The Burmese python is therefore globally classified as a “threatened” species. Overall, the Burmese python has found the most success in the Florida Everglades, where it can hide in the vast, untouched, and diverse ecosystem.

The Florida Everglades, a Biodiverse Haven

The Florida Everglades is one of the largest wetlands in the world and an incredible source of tourism for the state. It is also the primary freshwater source for a third of Floridians, and provides water for most of the state’s agricultural ventures. None of these vital functions, however, are the reason that Everglades National Park was created. Instead, early local conservationists, such as the Florida Audubon Society and Marjory Stoneman Douglas, believed that the area’s unique and considerable biodiversity was worth preserving. These voices won despite fierce opposition from game hunters and other interested parties, and Everglades National Park was authorized by Congress in 1934 with the Everglades Act and formally established in 1947. It became the first US national park created to preserve biodiversity.

As biodiversity continues to decrease globally, the statistics comprising the Everglades become even more significant: the many endangered, endemic, and otherwise rare species comprising the Everglades should serve as a shining example of the importance of ecosystem preservation in the US. Instead, the Everglades today is only 50% of its original land size and faces an onslaught from many familiar sources. For one, agricultural activity in the greater Everglades Agricultural Area (EEA) has predictably led to fertilizers and pesticides being found in the Everglades system.

Everglades National Park
`Moni3`, public doman

Increased industrial and residential development in Florida has also had an impact. Many of these projects date back to the 1940’s, when large swaths of the Everglades were drained for industrial and agricultural purposes. These have resulted in a 70% reduction of water flow from Lake Okeechobee to the Everglades and beyond. The secondary effects of this decreased water capacity are serious. In addition to many rare species, the Everglades feature acres of peatland, consisting of soil incredibly dense with decomposed organic matter, leaving behind carbon and nitrogen. As these areas have received less water and experienced drought, allowing oxygen to move in and decompose the peat, releasing carbon, nitrogen, and other material into the atmosphere. Finally, the Burmese python has spent decades wreaking havoc on the Florida Everglades. In the face of these challenges, the Florida and federal governments have had limited success.

Other entities, however, have voiced concerns over the situation, as well as a desire to be involved in decision making, such as the local Seminole and Miccosukee tribes, who have called the Everglades home for generations. The Second Seminole War began in 1835 over the Seminole and Miccosukee peoples’ forced relocation west of the Mississippi from their reservation north of Lake Okeechobee in what is now central Florida. Many native forces used the Everglades as a refuge and meeting place during the conflict. By the third Seminole war, most of the nation had moved west, those who stayed dug deeper into the Everglades.

Today, the Seminole tribe is heading the ambitious Everglades Restoration Initiative, a $65 million dollar project that is mostly focused on improving the Everglades water system. The initiative aims to clean the water of pollutants, increase water storage capacity, and lobby for decreasing development projects in the greater Everglades area. Furthermore, the Miccosukee people have been successfully lobbying governments on behalf of the Everglades for decades, including fighting legal designations that would force the native population to vacate the Everglades. It is this continued ignorance from the government that has led organizations such as the National Academies to call for increased cooperation between the groups: after all, ancestral knowledge of the ecosystem predates western scientific knowledge. For one, the Miccosukee and Seminole peoples have a better understanding of how a restored Everglades should look. The governments of the United States and Florida have also had limited successes in addressing other issues plaguing the Everglades, such as an aforementioned invasive species.

A Long Way From Home

Rome wasn’t built in a day, and neither was the Florida Everglades branch of the Burmese python family. The first pythons in Florida arrived in the 1970s and early 80s as a popular exotic pet. However, breeders and owners alike allowed many snakes to escape into the wild. These individual cases mostly slipped by undetected. The real catalyst for today’s python crisis was Hurricane Andrew, which hit Florida in 1992 and led to many snakes escaping from a breeding facility.

These snakes rapidly found a home in the familiar, subtropical Florida Everglades, where their r-selected tendencies helped them thrive.

But what exactly is the problem with the Burmese python being in the Everglades? An invasive species thrives at the expense of the health of a larger ecosystem. Much like their fellow invasive species, such as the Asian Carp, the Burmese python is a predator with an appetite so large that their new ecosystem cannot provide enough food. It’s what’s known as a carrying capacity overshoot. In the Everglades, their unchecked predation devastated native mammal populations.

Although the snake primarily snacks on small mammals, no creatures are really safe. A widely cited 2012 study found that between 1997 and the publication, raccoon numbers in the Everglades (once an incredibly common sight) had declined by 99.3 percent. Fellow common mammals in this study barely fared better, with all population crashes being over 85%. Most damningly, sightings of these animals were often in areas where pythons were not present or had only been recently introduced. Other species, like marsh rabbits and foxes, “effectively disappeared over that time.” Today, estimates of their population in the Everglades range from 100,000 to 300,000 individuals.

Female Burmese Python with eggs
Photo: Tigerpython

A Serpentine Smear Campaign

It wasn’t until 2000 that the Burmese python was officially recognized as an established species in the Everglades. In 2006, the Florida government took a soft approach to eliminating pet python releases with the new Exotic Pet Amnesty program.Through this program, pet owners could connect with parties interested in taking their unwanted pets free of charge. Two years later, the Florida Fish and Wildlife Commission (FWC) decreed the python as a “reptile of concern.” This distinction meant that the Burmese python could only be kept as a pet after a potential owner jumped through bureaucratic hoops.. The effectiveness of these solutions to the python’s presence in the Everglades was limited, as working to prevent snake releases does not address the already-established local population.

It is important to note that during this early period, the most effective and robust solutions to the python invasions came from local and national non-profits. In 2008, the Nature Conservancy launched its Python Patrol program for the Florida Keys, an initiative that trained volunteers in the best methods of python seeking and euthanizing. The Nature Conservancy partnered with Everglades National Park in 2010 and the FWC took over the program following its success.

A parallel yet arguably more impactful program was that of the local Conservancy of Southwest Florida. Unlike the Nature Conservancy, their efforts comprise a larger number of innovative strategies. Firstly, they considerably publicized the efforts of their eradication and removal volunteer crews: several videos went “viral” on a global scale, which helped raise awareness toward the issue. They also pioneered a high-tech elimination strategy that involved catching and airtaging male pythons of breeding age in order to track their movements to python nests.

In 2012, the Obama-era US Fish and Wildlife Administration decided to weigh in on the python problem. The Burmese python, along with several other exotic snakes, was designated as a Prohibited Species under the Lacey Act. This act is one of the oldest pieces of conservation legislation in the United States. Dating back to 1900, it bans the interstate sale and purchase, importation, exportation, etc, of a list of specific plant and animal species without a permit. Later amendments were more comprehensive and dealt with wildlife shipment labelings, timber supply chains, and other mechanisms affecting the transport of foreign species. The ability to own one of these animals, such as the Burmese python, is a matter left for individual states to decide.

Despite a myriad of eradication efforts, experts and officials share the opinion that eradicating the Burmese python from Florida is nearly impossible.

Lessons Learned

Unfortunately, it is far too easy to blame the processes of government in this story, as decisive action was quite delayed. Legal theorists over the years have also pointed out that the Lacey Act has a loophole, whereby government agencies cannot take action against an already established invasive population. In the future, should it be the responsibility of the government to take preemptive preventative measures to protect biodiversity? Despite their smaller role in this story, I would venture a yes: as development projects threaten the stability of the Everglades as a water purifier and essential ecosystem, the law is needed to stop these endeavors in spite of the market forces demanding their creation.

The state of Florida remains an absolutely essential player in hopes of preserving the Everglades. However, the old and continuing story of Everglades conservation is absolute proof of the power of non-government entities to motivate legal and public policy actions. The state would therefore be wise to consult not only pioneering non-profit conservationists, but the longtime local experts that call the national park home.

Alexa Hankins is a student at Boston University, where she is pursuing a degree in International Relations with a concentration in environment and development policy. She discovered Bio4Climate through her research to develop a Miyawaki forest bike tour in greater Boston. Alexa is passionate about accessible climate education, environmental justice, and climate resilience initiatives. In her free time, she likes to read, develop her skills with houseplants, and explore the Boston area!

Featured Creature: European Starling

What species sang part of a Mozart concerto and got its own musical tribute in return?

European Starling (Image Credit: Наталия via iNaturalist)

During my studies in urban governance, we took a course on complex systems thinking. I’ll spare you the technical details, but we learned that starling bird flocks were commonly used in the discipline to illustrate how complex systems work and emerge. The core idea was that complex systems are made up of many interacting components that, together, give rise to large-scale, coordinated behavior.

Years later, after I’d moved to the southern end of Rotterdam, I was hanging out in my living room, looked out the window, and there it was: a gigantic flock of starlings swirling through the sky. It was one of the most breathtaking natural events I’ve ever had the privilege of witnessing. And honestly, in a city like this, it might be one of the only natural events you can witness from the comfort of your living room or backyard.

Since then, I’ve spent countless hours watching these flocks from my rooftop during the months when they migrate through the city. As mesmerizing as it is to see them dancing in the sky, it’s even more incredible to watch them land. Just behind my house is a community garden with a few tall trees. The starlings will form a massive swarm around a tree, circling it with this eerie coordination. Then, seemingly out of nowhere, one bird dives into the branches — and within seconds, hundreds follow. The sound that follows is something else entirely: the collective chirping of all those birds packed into one tree fills the whole neighborhood. It’s chaotic, but in the most beautiful way.

More Than a Blur in the Sky: A Closer Look at the Starling

I was often confused about what exactly a starling bird was. Their song was always striking to me, but I noticed something odd: two very different-looking birds seemed to be making the same kind of sounds. At first, I assumed it might be a gender difference. But after doing a little research, I learned something fascinating: starlings change their appearance with the seasons, adopting a specialized breeding plumage during the mating season.

In the fall and winter, starlings appear dark with cream-colored speckles scattered across their bodies. But in spring and summer, when males enter breeding season, they undergo a striking transformation. Their feathers turn glossy and iridescent, shimmering with greens and purples, especially along their nape, breast, back, and wings.

Many birds change their plumage to attract a mate. Ducks are a classic example you might already be familiar with. But what makes starlings unique is how they transition. Unlike most birds, which molt (shed and replace their feathers) before breeding season, starlings don’t actually molt at all.
Instead, they lose their spots through abrasion. The speckles we see in winter are just the cream-colored tips of their feathers. As the season progresses, these tips gradually wear off from contact and movement, revealing darker, melanin-rich parts of the feathers underneath. Melanin makes those parts more resistant to wear, so while the pale tips disappear, richer tones remain, just in time for mating season.

Interestingly, adult females don’t become as glossy or glittering as their male counterparts. They tend to retain more of their pale speckles, giving them a lighter, spottier appearance that makes them relatively easy to distinguish.

Adult male (bottom) and female (top) starlings. Image Credit: Franck Curk via iNaturalist

Nesting: Homes, Herbs, and the Hunt for a Male

With breeding plumage in place, unpaired males seek out suitable nesting sites and begin building nests to attract females. To impress, they decorate their bachelor pads with flowers, greenery, and even herbs. It’s theorized that the quantity and quality of these ornaments play a role in courtship, helping males stand out in a competitive mating environment. Interestingly, once a female chooses a mate, she typically disassembles the decorations he so carefully arranged.

Turns out, birds might also be into a bit of aromatherapy — when they add herbs to their nests, they seem to chill out and parent better. The cozy, scented setup is linked to more positive vibes during egg-sitting duty.

Another curious aspect of their nesting behavior is how females lay their eggs. A typical clutch consists of 4 to 6 eggs per year, but if the first egg is removed — by a predator, researcher, or accident — the female will sometimes continue laying more eggs in an effort to compensate and make the clutch “whole” again.

If the home decor isn’t enough to impress a mate, ambitious bachelors have another trick up their wings: their song. These birds are among nature’s finest impressionists.

Song: The Starling Bird’s Signature

European starlings have a rich and varied vocal repertoire — clicks, whistles, rattles, snarls — and an extraordinary talent for mimicry. They can imitate other birds, animals, and even human-made sounds like car alarms.

This video highlights the incredible variety of sounds starlings are capable of producing.

This song plays a key role in courtship. Males sing to mark territory, attract mates, and signal their fitness. Often, these songs are performed near a decorated nest, combining sound, sight, and scent into a single courtship display. Research suggests females may prefer males with larger song repertoires, which could indicate intelligence, health, or age.

This vocal ability has long captivated humans. Mozart famously owned a pet starling that could sing part of one of his piano concertos. Urban legend holds that his piece A Musical Joke was inspired by the bird’s playful, unpredictable style, a feathered composer in his own right.Here’s a link to A Musical Joke if you’re curious, you decide!

Black Suns and Bird Ballets: The Science Behind Starling Flocks

As captivating as a single starling may be — with its shimmering feathers and complex song — their true magic emerges in numbers. When thousands gather, they move with a grace and synchronicity that seems almost unreal.

A murmuration of starlings at Gretna. (Image Credit: Walter Baxter via WikiCommons)

Starling flocks, called murmurations, are most often seen in winter when the birds gather to roost in huge numbers. Just after sunset, they form breathtaking patterns in the sky before settling for the night.

These movements are often likened to a kind of dance or aerial ballet. When the flocks grow large enough, they can even appear to obliterate the setting sun, a phenomenon so striking it inspired the Danish term “sort sol,” or “black sun.”

These spectacular displays aren’t just for show — these murmurations help protect against predators by confusing and overwhelming their vision, making it difficult to single out any specific target. They also aid in communication and guide birds to communal roosts, especially during colder months

But how do these birds move with such perfect synchronicity? It almost looks choreographed, but it’s not like the birds wake up early and go to synchronized flight practice to drill until everyone hits their marks. What’s actually happening is that starling flocks are showing off a rare and fascinating phenomenon called scale-free correlation. Sounds complicated, sure, but it’s actually pretty simple.

It means that the birds’ movements are coordinated no matter where you look in the flock — whether you’re watching birds that are right next to each other or birds that are far apart. The changes ripple through the entire group almost instantly.

What’s even more amazing is that there’s no leader. Unlike geese, which follow a clear leader in formation, starling flocks are totally decentralized. Each bird watches and responds to just its 7 closest neighbors — that’s it. But because every bird is doing this at the same time, the entire flock ends up moving as one super-organism.

It’s like a message passing through the flock: when one bird moves, its neighbors adjust, and their neighbors adjust, and so on. This chain reaction spreads through the whole group — and that’s what we mean by scale-free correlation: coordination that works across any size or distance, without a central controller.

See the coordinated movement of thousands of starlings in this short video of a murmuration in action:

Watching them gather in those immense, swirling formations from my rooftop — the very phenomenon that first sparked my interest years earlier — brought everything full circle. What once was an abstract example in a systems theory class had become a living, breathing presence in my everyday life.

And what’s perhaps most astonishing of all is that this beauty isn’t just instinct — it’s adaptation in action.

Global Spread and Genetic Genius

Few avian species have been as globally successful as the European Starling (Sturnus vulgaris). Today, starlings can be found thriving on every continent except Antarctica — a remarkable feat for a bird species that, in many places, didn’t even exist 150 years ago.

North America’s starlings trace back to a strange little story: in the 1890s, a group of Shakespeare fans released about 100 birds in Central Park, hoping to populate the continent with every bird mentioned in his plays. Most of their efforts fizzled — but the starlings didn’t. They took off, quite literally, and today their descendants are spread far and wide across the U.S., Canada, and even into the Caribbean and Central America.

Elsewhere, starlings were introduced intentionally for pest control, such as in Australia, South Africa, and New Zealand, where they were thought to help manage insect populations in agricultural settings.

But what is it about this species that has allowed it to become so incredibly widespread?

Part of what makes starlings so successful is how adaptive they are. They’re just as comfortable in cities as they are in farmland, nesting in everything from building vents to backyard trees. As long as there’s something to eat, bugs, grains, scraps, they’ll make it work.

They’re also smart; starlings have big brains for their size and it shows. They can solve problems, learn from each other, and figure out new ways to find food when times get tough. And they’re almost never alone. Whether foraging, roosting, or migrating, they move as a group, watching, listening, adapting together. It’s part of what makes them so good at surviving in unfamiliar places.

Starlings also exhibit what’s known as environmental niche flexibility, meaning they can adjust their physical or behavioral traits in response to a wide range of environmental conditions. It enables them to inhabit ecosystems ranging from humid woodlands to dry grasslands with relative ease.

What’s more, they’re not just surviving across these ecosystems, they’re evolving. In just over the course of a century, starlings in North America have started adapting to their new homes. Arizona birds are showing signs of handling heat and dryness, while their cousins up in the Pacific Northwest are built for cool and damp. It’s a rare, real-time glimpse of evolution in motion.

But this incredible adaptability also brings starlings into conflict with human systems, particularly in agricultural landscapes, where their success reveals deeper tensions between wildlife and the ways we use the land.

Starling bird in flight. (Image Credit: Radu L via iNaturalist)

Fields of Conflict: Starlings and Agriculture

The more I learned about starlings, the more I realized their story is tangled up in ours, especially in how we farm. These birds didn’t set out to invade feedlots and barns. They ended up there because the open meadows they once thrived in are disappearing.

Starlings evolved to forage in grasslands, digging through the soil for grubs and larvae. But as fields are replaced by monocultures filled with pesticides, they’ve had to adapt — and fast. Livestock farms offered what the land no longer did: bugs in the soil, water to drink, and plenty of places to nest. It’s not that they prefer our barns. It’s just that there’s nowhere else to go.

The irony is that what farmers often see as nuisance behavior is really just resilience in action, starlings making do in a landscape that’s no longer built for them.

For these farmers, starlings can be a real headache. They sneak into barns, eat livestock feed, and leave behind messes that can damage equipment and pose health risks. And they’re clever, most scare tactics only work for a little while before the birds figure them out. Remember those big brains? So while their presence speaks to larger ecological loss, the day-to-day impact is very real for people trying to make a living off the land.

Despite their reputation as a nuisance in agriculture, starlings are actually experiencing serious population declines — not only in their native range but also in parts of their introduced range, including the UK and North America.

This is often overlooked in public discourse. In the UK, for instance, starlings are now a protected species, due to sharp population drops attributed largely to the loss of high-quality foraging habitats and changes in land use.

Interestingly, their decline has not led to a rebound in the native species they’re often accused of displacing — suggesting that habitat loss, not species competition, may be the deeper issue.

(Image Credit: Alena Fionina via iNaturalist)

Rethinking Narratives

It’s easy to label starlings as pests — especially in an industrial system where every loss counts. But that framing often misses the bigger picture. Their presence on farms isn’t just about opportunism; it’s about what’s missing from the land. If pastures were healthier and ecosystems more intact, maybe starlings wouldn’t need to forage in feed troughs or nest in sheds.

If agriculture were managed more sustainably, with more permanent pasture and diversified cropping systems, it’s likely that starlings would rely less on feed troughs and barns. In this light, controlling starling populations without addressing the root causes of their shifting behavior may be shortsighted.

Conservation in their native range should focus on restoring pasture ecosystems and rebuilding invertebrate populations. In their invasive range, managing their numbers in sensitive areas is important — but must go hand-in-hand with reconsidering how intensive farming practices shape the ecological playing field.

Each season, I look up from the same rooftop, and the starlings are there — not thriving, not vanishing, just enduring in the spaces we’ve left behind. Their presence doesn’t signal ecological balance, nor does it mark collapse. Instead, it speaks to something quieter: the capacity of life to persist in the margins, to find rhythm in disruption, and to adapt — however imperfectly — to a world in flux. In them, I see the echoes of our choices and the quiet, complicated resilience of the wild.

Lakhena Park holds degrees in Public Policy and Human Rights Law but has recently shifted her focus toward sustainability, ecosystem restoration, and regenerative agriculture. Passionate about reshaping food systems, she explores how agroecology and land management practices can restore biodiversity, improve soil health, and build resilient communities. She is currently preparing to pursue a Permaculture Design Certificate (PDC) to deepen her understanding of regenerative practices. Fun fact: Pigs are her favorite farm animal—smart, playful, and excellent at turning soil, they embody everything she loves about regenerative farming.

Dive Deeper

Featured Creature: Japanese Knotweed

With leaves shaped like a spade, what plant
is known to invade and refuses to fade?

The Japanese knotweed (Reynoutria japonica)

Japanese knotweed flowers (Cbaile19 via Wikimedia Commons)

On a warm spring afternoon, my friend and I explored a creek off the Mill River, in Northampton Massachusetts. Thick green bushes lined the banks, making it difficult to reach the water’s edge. As we scoped for a route through, my friend pulled on a nearby branch, inspecting its leaf.

“Japanese Knotweed,” she identified, grasping the plant at the thick part of its stem and straining to pull it up . “This was my whole summer.”

She’d worked on a farm the previous summer and spent countless hours eradicating weeds, which, as it turned out, were mostly Japanese knotweed.

I too am familiar with knotweed. As a child, I mistook Japanese knotweed’s hollow stems for bamboo, often wielding them as makeshift swords. At the time, I thought of the plant as little more than a plaything, unaware of the complex role it was playing in the ecosystem around me.

Photos courtesy Jim Laurie

Where does Japanese knotweed grow?

Japanese knotweed is native to East Asia in Japan, China, and parts of Korea and Taiwan. The plant was introduced to North America in the late nineteenth century, to be used as an ornamental plant. Its introduction, however, had unintended consequences as it invaded wetland, stream corridors, forest edges, and drainage ditches. Japanese knotweed is a herbaceous perennial plant (a non-woody plant that regrows each year from its roots), that can grow to be up to 11 feet tall, with jointed hollow stems resembling that of, yes, bamboo. So you can forgive my childhood ignorance. The stems are bright green and grow nodes which can range in color from red to purple. The knotweed’s spade-shaped leaves grow from these nodes, with a square base and sharp point. They thrive in full sun but can also grow in partial shade, and do well in a variety of soil and moisture conditions. It can often be observed on the banks of rivers, wet depressions, and woodland edges, or in more built environments, including construction sites and roadways.

During the summer, from the nodes of the knotweed bloom small white and pale green flowers. These little flowers are 3 to 4 inches long, and grow in fingerlike clusters, with each cluster holding a couple dozen flowers.

Japanese knotweed (Larrissa Borck via Wikimedia Commons)

While Japanese knotweed is known as an invasive species in many parts of the world, including throughout the United States, in its native range it plays a much different role. There, it exists in balance with local ecosystems, kept in check by native insects, fungi, and herbivores that have evolved alongside it. Instead of forming dense monocultures that crowd out other plants, knotweed grows as part of diverse plant communities, coexisting with a wide variety of species.

Unlike in North America and Europe, where few animals or insects consume it, knotweed supports a variety of wildlife in its natural habitat, and its nectar is enjoyed by bees and butterflies, especially in late summer when other flowers have faded. Insects such as the aphid Aphalara itadori and various beetle species naturally feed on knotweed, limiting its dominance and allowing native plants to thrive alongside it. Some fungi, like Mycosphaerella leaf spot, help regulate its growth, preventing the unchecked spread seen in non-native environments. These interactions ensure that Japanese knotweed remains just one part of a broader ecosystem rather than an overwhelming force.

Ecologically, Japanese knotweed plays an important role in nutrient cycling and soil formation. Its deep, extensive rhizome network helps stabilize slopes prone to erosion in Japan’s more volcanic landscapes, helping to prevent landslides and maintaining soil structure. Additionally, the plant’s decomposition contributes to organic matter in the soil, enriching the surrounding environment.

But when introduced elsewhere, many of these ecological checks and balances are missing, allowing knotweed to spread aggressively and disrupt local biodiversity.

How does it spread?

Japanese knotweed reproduces through both seeds and rhizomes, an underground root-like system which produces shoots of new plants, coming up through the earth. As much as two-thirds of the plant’s biomass is stored in this network.

Seeds of the Japanese knotweed (Famartin via Wikimedia Commons )

The knotweed can be found around the world, far from home. It was introduced to the United Kingdom in 1825 and has since spread across Europe. The majority of Japanese knotweed populations in Europe descend from a single female genotype, though hybridization with related species has introduced some genetic variation. This female genotype is able to receive pollen from a close relative, called the giant knotweed. The combination of these two plants produces a hybrid known as the Bohemian knotweed, which is also spreading across Europe.

In North America, however, the Japanese knotweed reproduces differently than its European counterpart. Even though the European female clone is widely dispersed around the United States, this clone is not the only genotype present. Populations of both male and female Japanese knotweed have been identified across America. The female Japanese knotweed does not produce pollen and primarily spreads through those rhizomes, though it can also reproduce via seeds when pollinated by a related species. Male Japanese knotweed, on the other hand, do produce pollen, as well as occasionally producing seeds.

Impact

Japanese knotweed grows in thick clusters, emerging during early spring time and growing quickly and aggressively. This dense stand of plants crowds out native vegetation, depriving them of resources needed for reproduction and survival.

Japanese knotweed by the water (Dominique Remaud viaWikimedia Commons)

Japanese knotweed thrives in moist, shaded environments. On stream banks, it outcompetes native grasses and shrubs, reducing biodiversity. This lack of diversity along the bank causes instability, and makes it more likely that the soil will shear off during flooding, increasing the amount of sediment deposited into the water. This erosion sends soil and Japanese knotweed seeds into the creek, allowing the plant to spread downstream and further destabilizing the stream bank.

Foraging Japanese knotweed

The young, spring shoots of Japanese knotweed are not only edible, but also delicious! The plant has a tart, slightly sweet taste, similar to that of rhubarb. It can be turned into a jam, put in salads or a stir fry, and used as a crunchy addition to sushi. Where it is native in East Asia, knotweed has been used in traditional medicine for hundreds of years. Owing to the plant’s invasive nature, practicing responsible foraging is crucial to avoid accidentally spreading the knotweed populations. In order to properly dispose of the leftover plant matter, it must be boiled, burned, or thoroughly dried out before discarding in order to ensure that no knotweed is spread. Foraging and eating Japanese knotweed can be a way to help control the plant, through the repeated cutting of the stems. The following video shows a recipe for homemade Japanese knotweed pickles!

Managing knotweed

Due to its dense clusters and deep root system, once established, Japanese knotweed is incredibly difficult to remove. Manually, populations can be managed through repeated cutting, though complete removal of rhizomes is extremely difficult and can sometimes lead to further spread of the knotweed. When it comes to cutting, the stems of the plant must be cut three separate times during the growing season in order for this to be an effective treatment. In terms of digging up the roots, this can be very labor intensive, and the process of digging Japanese knotweed can unintentionally cause the spread of rhizome fragments, which can result in even more Japanese knotweed on your hands!

Japanese knotweed’s spade-shaped leaf (Flocci Nivis via Wikimedia Commons)

Through dedicated work, such as that of my friend who spent three months eradicating Japanese knotweed on her farm, the populations and impacts of the plant, when invasive, can be mitigated. With a little time and effort, you can help control knotweed in your own backyard…and maybe even harvest some for dinner.

Helena is a student at Smith College pursuing psychology, education, and environmental studies. She is particularly interested in conversation psychology and the reciprocal relationship between people and nature. Helena is passionate about understanding how communities are impacted by climate change and what motivates people towards environmental action. In her free time, she loves to crochet, garden, drink tea, and tend to her houseplants.

Sources and Further Reading:

Featured Creature: Cheatgrass

What plant plays an important role in the grasslands of its native hemisphere, but alters soil moisture and fire regimes when introduced in North America?

Cheatgrass (Bromus tectorum)!

A cheatgrass seed had needled its way into my skin again. I thought that I had freed myself of the cheatgrass when I came back east, to the land of ample water and broad leaves, and threw all of my camping gear into a dark corner of my bedroom. This was not so – it was hiding out in my sock drawer. When I pulled up my socks, I dragged the pointed tips of the cheatgrass seeds up my ankles, and I was once again somewhere out west, nursing the delicate white surface wounds that they left. I was, for the first time, not grateful for the tight warmth-trapping weave of my wool hiking socks – it is highly adept at locking the lance-like grass seed into a comfortable chamber from which it can prod at my ankles. The cheatgrass survived the washer and the dryer and my prying fingernails, survived my desperate attempts to wrench it out of my socks and into the campfire. Cheatgrass burns fantastically well– it’ll ignite from marshmallow-toasting-distance and beyond.

My cheatgrass came with me from Wyoming months ago. Out there, it rolled for miles across the sagebrush steppe, slowly but surely creeping into every space between every shrub. The site where I gathered the seeds into my socks smelled more of earth than sagebrush, which was unusual for the basins where I’d been working. My boss Rachel and I hopped down out of our work truck and took in our site: some sagebrush, sure, but only a few dashes of it scattered between rolling hills of crisp, flame-red cheatgrass. The site was nearly silent; I found myself missing the usual distant whirrr of farm machinery and the cacophonous cry of a startled sage grouse. We were instead accompanied by the whistling of wind and the knowledge that we would be blowing dust into our handkerchiefs for a few days.

The Sagebrush Steppe near Big Jacks Creek Wilderness, Idaho, has been almost entirely taken over by cheatgrass.

“Downy Brome”

Some call cheatgrass “downy brome”, which is a perfect term for it in the early spring when it hasn’t grown into its wretchedness. In early spring, when its long awns have not yet grown stiff and sharp, it is a soft and elegant plant. Its leaves fall in a gentle cascade from the long stem. The downy brome rolls over hillsides and whispers to its sisters in the breeze; as they dry in late summer, the wind knocks the heads of their seeds against one another, and they are scattered to the ground to start their cycle anew. When the cool season rains end and they’ve sucked up all the water they can from the parched earth, their chloroplasts finally falter, and the grass turns a faint purple-red from the awn-tip up. In spring, the dusty green tones of the sagebrush and the brightly-colored grass dapple the landscape. By summer, the sagebrush is nearly overtaken by an orange-brown, foreshadowing the fire which cheatgrass so often fuels. The grass sticks its seeds through your shoes and between your toes and into your socks and the hems of your pants. It doesn’t matter if you stop to pull them out– you will have just as many jabbing and nudging away at you after you walk another ten feet through their swaying abundance. It is useless to shake them out, too. You must pull them, piece by piece, out of your hair and your tent and your boots, and cast them to the ground. This is just what they wish for– you are seeding them for next year.

A rugged invader

Humans introduced cheatgrass to the Northeastern United States by accident sometime around 1860. You can find it in many places around New England, but in the presence of such an overwhelming amount of water, it often fails to compete with its fellow grasses and is relegated to cracks in sidewalks and highway islands full of compacted, inhospitable soil. Cheatgrass seems lost on this coast; few in the East know what it is or why it’s here. It is a plant surviving as plants do, regardless of the “invasive” status we’ve thrust upon it. In the West, however, its success is something wicked and wonderful.

Any water from the winter’s snowmelt or early spring rains gets sucked up by the eager roots of the cheatgrass, leaving little for the still-sprouting native grasses, forbes, and shrubs, even as their taproots probe deep into the earth. Ecologists curse the plant for its brutal efficiency in driving out those native to the arid steppe; birders lament the loss of woody habitat for their feathered favorites; ranchers sigh at the sight of yet another dry, nutritionally-deficient plant that even their toughest cow is loath to graze. And there is, of course, the fire. Cheatgrass dies and dries in the early summer, long before native grasses do, providing an early fuel source for the ever-lengthening fire season.

Cheatgrass seeds
Jose Hernandez, USDA (Public Domain via Wikicommons)

The seeds lie in wait in the earth, and in the spring, they unfurl their new leafy heads and emerge from between blackened sagebrush branches. In the grass’s native range in Europe and Southwestern Asia, the plant is no worse or better than any other; it just is. Moths and butterflies lay their eggs along its edges. Ungulates nibble it slowly as their eyes each search opposite directions for the next snack.

Nearly all of the existing research on the plant explores its role far from home, in the United States. It is grass, and it would be hard to imagine that here on the other side of the world, some field tech is cursing its very existence. You’d never know from looking at the cheatgrass that ranchers and federal scientists alike have spent years dousing their own lands in herbicides with the hope of its extirpation. We humans have of course played our role in keeping the cheatgrass strong even as we try to drive it out, since cheatgrass, like many invasives, is far better at taking over already-disturbed soils where the native plant communities and biological soil crusts have been weakened. As extreme wildfires, agricultural use, overgrazing, and the general ravages of climate change continue to impact larger and larger regions, so too does the invasive capacity of the cheatgrass.

I wore a different pair of socks hiking that day for fear of bringing more cheatgrass to Connecticut. It was silly, though; the cheatgrass already knows this land well.

Jasmine

Jasmine Gormley is an environmental scientist, writer, and advocate from New Hampshire. She holds a BS in Environmental Studies from Yale, where she conducted research in plant community ecology and land management. She aims to obtain a degree in environmental law. As a first-generation college student, she is passionate about equity in educational and environmental access, and believes that environmental justice and biodiversity conservation are often one and the same. In her spare time, you can find her rock climbing, foraging, and going for cold water swims.

Sources and Further Reading:

Featured Creature: Asian Giant Hornet

Photo from wikipedia.org

What creature comes from Southeast Asia, is the biggest of its kind, eats animals we need, and has been tried and convicted of murder in the court of public opinion?

Meet the Asian Giant Hornet!

Warning: This is not your warm and cuddly Featured Creature.

It was a warm and pleasant day last summer, and some of us Bio4Climate folks were entertaining out-of-town guests at our Miyawaki Forest in Cambridge, Massachusetts. During lunch, a biologist from central Europe expressed horror at the appearance of a “new” insect. She described it as the largest wasp she had ever seen (the differences between wasps and hornets are primarily coloring and size).

What do you think?

Photo: Gary Alpert
https://en.wikipedia.org/wiki/File:Vespa_mandarinia.jpg

Indeed, it was a new insect in the Western Hemisphere – it landed in France in 2004. Before then, its home had been limited to Southeast Asia and Japan for 16 million years as a forest dweller that mostly lives in subterranean nests. Those in the know suspect that it somehow hitched a ride in pottery imported from China. Perhaps it’s a bit surprising that the hornet’s international travels took so long, given that globalization has been going on for many centuries.

Asian Hornet Size Comparison — Relative sizes for comparison, from vespawatch.be CC BY 4.0 license

In many places where this creature newly appeared, authorities put out the alarm and asked citizens to take a photo of it with their cell phones but do not touch it or disturb it in any way! It has a quarter-inch stinger and plenty of venom for repeated attacks. It’s rarely lethal to humans, but the sting has been described as driving a hot nail into your flesh. “Just tell us where you saw it and we’ll send in experts to try to find its nest” – no simple task with nests that are usually underground.

As it happens, people mostly mis-identified other black-and-yellow wasps as Asian Giant Hornets so the alarm was somewhat false – but the threat was real. And the spread could happen quickly, as it did in Belgium:

Asian hornets in Belgium: *August* ***2018***, ©Vespa-Watch

Asian hornets in Belgium: *August* ***2020***, ©Vespa-Watch

Asian hornets in Belgium: *July* ***2022***, ©Vespa-Watch

If these maps resemble our recent and devastating infectious global invasive-species explosion, Covid-19, it’s not a coincidence. Zoonotic diseases – illnesses that jump from nonhuman animal hosts, including insects, to humans – present in patterns that resemble the spread of hornets. The threat of another potential pandemic, albeit non-microbial, should ring alarm bells everywhere.

But that’s a story for another day. The current question is, “Why are we so worried about the Asian Giant Hornet?” True, it’s a painful sting, but is there something else?

Yes, indeed.

This hornet’s favorite food is honey bees. The bees don’t stand a chance against these aggressive and much larger adversaries. A small crew of invaders can decimate a nest of thousands of bees in a few hours. Their powerful jaws quickly decapitate their victims; they proceed to chew up the body into “meatballs” and deliver the meals to their own offspring. Hence the nickname “murder hornets,” although that is rather overly dramatic – all carnivores eat other creatures. After all, it’s an essential job in almost all ecosystems to keep a habitat’s checks and balances are working.

Bees in the hornet’s native South Asian habitat do have a defense, at least against only one or two invaders. A team of bees surrounds the hornet, beats their wings, and raises the temperature beyond hornet tolerance – and to victory!

Photo: Takahashi
A defensive ball of Japanese honey bees (*Apis cerana japonica*) in which two Japanese hornets are engulfed, incapacitated, heated, and eventually killed. This defense is also used against the Asian giant hornet.

Unfortunately, non-Asian bees haven’t had millions of years to figure out how to smother hornets.

Since honey bees are essential pollinators for many crops in addition to producers of honey, the appearance of Asian Giant Hornets in North America in 2019 mobilized beekeepers and agriculture big time. In 2020 officials warned that if the hornets become established, they “could decimate bee populations in the United States and establish such a deep presence that all hope for eradication could be lost.” As with many invasive species, when they establish themselves in a new place their natural predators usually don’t come along, and that disrupts the ecosystem’s function.

In the hornet’s defense from a homo sapiens perspective, it has some redeeming qualities. It’s only fair to say that it also attacks what we would call agricultural pests, and its larval silk proteins “have a wide variety of potential applications due to their [many] morphologies, including the native fiber form, but also sponge, film, and gel.”

Finally, given that every animal eats and gets eaten eventually,

In some Japanese mountain villages, the nests are excavated and the larvae are considered a delicacy when fried. In the central Chūbu region, these hornets are sometimes eaten as snacks or an ingredient in drinks. The grubs are often preserved in jars, pan-fried or steamed with rice to make a savory dish called hebo-gohan. The adults are fried on skewers, stinger and all, until the body becomes crunchy.

In gastronomy, there is hope!

P.S. “Vespa,” by the way, is the genus of wasps and hornets. So the next time you’re riding your bike and you hear an ever louder buzzing behind you, be grateful when it’s a gas-guzzling scooter and not its eponymous insect.

Extra featured-creature feature, red in tooth and claw:

By Adam Sacks

Sources:
https://www.discoveringbelgium.com/asian-hornets/
https://en.wikipedia.org/wiki/Asian_giant_hornet
Alfred Lord Tennyson In Memoriam A. H. H., 1850:
Who trusted God was love indeed
And love Creation’s final law
Tho’ Nature, red in tooth and claw
With ravine, shriek’d against his creed

Creature: Invasive Species