How Invasive Animals Threaten North American Ecosystems

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When native species exist alongside one another, this makes for a healthy ecosystem. However, introducing animals (and even plants) from another area can seriously interfere with the natural balance of things.

Studies reveal that invasive species disrupt local biodiversity, leading to long-lasting or even permanent damage. In the United States alone, there are over 15,000 documented invasive species, and their impact is typically far from positive.

Causes of Invasive Animal Species in North America

More often than not, invasive species are introduced to a new area through unintentional human activity. One example of this was when zebra mussels were brought to Lake Erie on cargo ships, and this is not an isolated incident. Sometimes, when wood and other natural products are shipped around the world, they contain insects which then thrive in their new location.

Sometimes though, humans will transport animals (and plants) to new areas as we move around the globe. This may be for things like the exotic pet trade. Now, I know what you’re thinking; these animals are contained. However, it only takes a few specimens to escape into the wild and, as long as the conditions are right, they’ll reproduce and thrive.

Humans are also responsible for introducing new species for their own enjoyment. In Europe, certain species of catfish have been introduced to local lakes for the benefit of hobby anglers.

In other cases, natural forces are responsible for bringing new species to an area. This could be when animals are forced to relocate because of changes to the climate or because they’re dragged to a new area by ocean currents and storms.

Impacts of Invasive Animal Species

One of the biggest problems with invasive species is that they will compete with our native animals for resources. Where alien species are strong enough, they can even outcompete native creatures, which can drastically reduce their populations. As a direct result of this, invasive species have a negative impact on local biodiversity and, in order for habitats to thrive, biodiversity is really important as it provides balance.

What’s more, some invasive species may prey on local wildlife, again causing a reduction in their numbers. Even if they’re not directly preying on our wildlife, these species may have negative impacts on the soil which can then make it harder for plants to grow, therefore reducing the food sources for our local herbivores.

On top of this, when plants are affected either through soil degradation or because invasive species are eating plants, this impacts local crop yields. As a result of this, agricultural businesses suffer, and this means that the economy takes a hit. Couple this with the money and resources that have to go into controlling these species and the effects are far wider than one might first imagine. Between 19860 and 2000, two invasive species caused more than $16 billion in damage; now just imagine the total when we consider all invasive species.

Continuing to look at the economical impact of invasive species, we only have to look at the expenses the United States are incurring every single year. Since the year 2001, it’s reported that this nation alone is having to fork out more than $137 billion annually in order to control invasive species and rectify the damage they have caused.

If that wasn’t enough, there’s also the potential for alien species to spread disease. In 2006, an outbreak of E. coli was attributed to the fecal matter of invasive wild pigs.

Invasive North American Animals

With thousands of animal and plant species having been introduced to North America over the years, this is certainly a topic that needs more awareness. While it would be impossible for me to discuss every invasive species, I would like to tell you a little more about some of those that have had the most profound impact.

1. Burmese Python (Python bivittatus)

Despite their name, Burmese pythons are not endemic to Burma; in fact, they’re found in the far reaches of Asia from India to China, as well as in parts of Africa and Australia. However, in North America, they are now part of the wildlife in Florida after breeding facilities were damaged by hurricanes.

These snakes first came to Florida in the 1980s, but it’s only been since hurricane Andrew in 2005 that they’ve been a significant problem. Humans have made a serious effort to control their population since then. In the last (almost) 30 years, the US has spent around $6 million trying to remove these snakes from the wild and raise awareness about them as well as performing several studies on their habits.

The problem is that the Everglades provide the perfect habitat for these snakes, but they’re preying on local wildlife, particularly mammals. Two endangered species have been found in the stomachs of deceased Burmese pythons, so it’s vital that efforts are made to remove them. What’s more, the snakes are thriving, laying up to 100 eggs per clutch, and this means that they’re outcompeting local species for resources.

2. Japanese Beetle (Popillia japonica)

As you can probably guess from its name, the Japanese beetle hails from Japan, but it was first introduced to North America back in 1916. Although it’s believed that the species could have been here since 1912 and arrived in a shipment of flower bulbs, and is now found in around 28 states. In Canada, it’s thought that the insects were first introduced around 1939 on a ferry from Maine.

Japanese beetles are now a common garden pest that are thought to damage as many as 300 different plant species. What’s more, they’re also known to feed on grass roots, which can be damaging to private property as well as commercial properties such as golf courses.

In agriculture, the use of crop covers has been shown to reduce the damage caused by Japanese beetles. The problem here, however, is that this often means hand pollination needs to take place, which can be costly in terms of time. In the garden, hand picking is often the best method of controlling populations.

3. Zebra & Quagga Mussels (Dreissena spp.)

The zebra mussel was first introduced to North America in the ballast tanks of ships and was first noted in the Great Lakes. However, since then, the species has been further spread around US waterways by smaller boats. In order to prevent any further mussels being brought into the country, the transport of ballast water has now been banned.

One of the biggest problems with zebra mussels and quagga mussels is that they have a tendency to clog up water pipes. There are many attempts to manually remove them but of course, this takes some serious man hours and resources. The power industry is one of the worst affected by these mussels and in a six year period, it was reported that these pests caused more than $3.1 billion worth of damage.

The issue with zebra and quagga mussels is how quickly they reproduce. Not only do they have the capacity to damage infrastructure, but they’re also known to negatively affect the ecosystem. For example, they will filter out important algae that our native species use for food, thereby eliminating resources.

Seen as one of the most dangerous invasive species, quagga mussels also deposit a lot of phosphorus into the water. Too much of this can cause serious damage to the ecosystem, but control over phosphorus levels has as good as been lost in four out of the five Great Lakes! So difficult are these creatures to get rid of that North American authorities are stumped and are, as such, offering a massive $100,000 to anyone who can come up with a viable solution. 

4. Asian Carp (Cyprinidae family)

Initially, the Asian carp was introduced in ponds in the southern parts of the United States as a way of trying to control algae. However, some fish escaped from the intended area and now cause serious problems in the Mississippi River and its tributaries.

There are reports of these large fish leaping out of the water and causing injuries to boaters. Even more worrying is how quickly these fish have bred. In sample sites, as much as 95% of the biomass was made up of Asian carp.

Efforts to try to control the populations of Asian carp include poisoning the fish as well as installing electric barriers to prevent them from spreading further. However, up until now, it’s estimated that around $80 million has been spent trying to rid the waterways of four species of Asian carp; silver, bighead, grass, and black, and there’s still a lot to do.

5. Nutria (Myocastor coypus)

The nutria is a species of large rodent, sometimes called the coypu and is native to parts of South America. However, since the early 1930s, they have been in North America after being brought to Louisiana for the fur trade. To begin with, populations were well controlled, but in the 1940s, a hurricane destroyed enclosures, allowing nutria to escape.

Nutria are found in areas where there is a lot of freshwater, being semi-aquatic. The problem is that they are tearing through the marshes and causing serious damage to local ecosystems. Not only are they eradicating several species of wetland plants, but they’re also known to wreak havoc on crops and will also eat small invertebrates; they’re really not fussy.

Now found in around 17 US states, nutria also carry diseases like tularemia, which can be passed on to humans. Fortunately, there are several large-scale operations in place that aim to eradicate populations. In Louisiana, a project that’s been running since 2002 has seen around 400,000 nutria removed from the wild. Although this was after a whopping 15,000 acres was reported to have been damaged by these creatures. 

6. Cane Toad (Rhinella marina)

Originally found in South and Central America, the cane toad is a large amphibian species that has been introduced to many countries, particularly in the Pacific regions. While it is native to Texas in North America, it has now been introduced to Hawaii and Florida. These have been both accidental and intentional introductions. One such example of this was the attempted introduction to Louisiana, although this was not successful.

In Florida, these toads were initially introduced as a way of controlling sugarcane pests. However, the toads did not establish. It was only after an accidental introduction via Miami airport in the late 1950s that the toads finally made their mark.

The cane toad is toxic which poses a risk to pets in North America, and anything that predates the road is also at risk. On top of this, the species preys on local wildlife, having a dramatic impact on the balance of the ecosystem.

That said, since cane toads are not protected by law, it is permitted for homeowners to humanely kill them should they find them on their property (keep in mind that there are anti-cruelty laws in place that cover this species.) Keeping your garden tidy and well maintained with a trimmed lawn is one way to deter these dangerous pests.

7. Brown Marmorated Stink Bug (Halyomorpha halys)

The brown marmorated stink bug is native to parts of Asia, including China, Korea, and Japan. However, the species was introduced to North America in the late 90s and is suspected to have arrived on shipping pallets. While the first specimens were seen in Pennsylvania, it was only a couple of years down the line that reports were coming in from places like New Jersey.

Since then, these rapidly reproducing bugs have been reported in as many as 37 of the United States and even parts of southern Canada.

The main issue with stink bugs is the damage they do to crops. What’s more, they’re not particularly fussy in what plants they feed from but are known to pierce the fruit, causing it to lose moisture. Because of this, the brown marmorated stink bug is thought to threaten around $21 billion worth of US crops!

It’s the US Agricultural Department that has been tasked with the responsibility of trying to control these pests and have done so via the discovery of a pheromone that attracts the bugs. Farmers are then able to use this to lure the stink bugs into traps.

8. Emerald Ash Borer (Agrilus planipennis)

Native to eastern parts of Asia, including northern China, Korea, Mongolia, and Japan, the emerald ash borer is a pretty attractive insect. But it would do far better remaining in its home territory owing to the damage it causes to the ash lumber industry. So much so that it’s estimated that these bugs put a dent in the lumber economy of more than $25 billion every year!

Emerald ash borers are now found across the eastern portion of the United States after first being introduced from Japan in 2002. It’s believed that they successfully made the journey in batches of untreated wood.

The potential damage to the lumber industry is staggering, but there are attempts being made to control the populations. The good news is that, while this species is strong, it doesn’t fly well, so usually remains in one area once established. Using insecticides on affected trees seems to be beneficial, but the cost is eye-watering. Not only this, but removing affected trees and replacing them is estimated to cost around $10 billion dollars, and that doesn’t even include the removal of forests!

9. European Starling (Sturnus vulgaris)

In the 1900s, the starling was introduced to Central Park in New York City in an attempt to bring animals from the works of Shakespeare to North America. Only 100 birds were released at the time. I suspect that humans did not then realize how quickly their populations would grow and how damaging that could be. 

Now, these invasive birds are found all over the mainland US, and it’s thought there could be numbers in excess of 200 million. While native birds are protected in the United States, it is permissible to hunt and/or trap these pests. You are also allowed to destroy nests and use chemicals called starlicides to control populations. However, these also come with the risk of harming native species, so caution is advised.

The problems that the European starling causes are many. For example, they’re crop pests that cause hundreds of millions of dollars worth of damage each year, affecting the agricultural economy. What’s more, they pose a risk to native bird species owing to the fact that they will invade their nests.

For humans, the threats are just as significant because starlings often congregate in large flocks, which have been known to wreak havoc at airports. Moreover, since they carry dangerous diseases, like salmonella, they’re a threat to human health.

10. Northern Snakehead (Channa argus)

Northern snakeheads are a species of fish native to China, Korea, and Russia, where it is a common food fish. Due to its economical importance, it was introduced to both Europe and North America where it was first seen in Maryland in 2002.

The northern snakehead is an apex predator, which means that it has the potential to significantly damage the biodiversity and balance of the eastern US fresh water bodies it inhabits. What’s more, there are concerns that this aggressive species may outcompete native predators, further affecting and altering the local biodiversity. Moreover, it has been reported that the species could introduce diseases that would threaten local aquatic life.

This species is such a significant threat that it is not illegal to have a live specimen in your possession. What’s more worrying is that the spread of the northern snakehead is now far and wide and is fast approaching the Great Lakes, where it could massively interfere with the local ecosystem. In some areas, piscicides have been used to eradicate populations and this has seen good success rates. However, the chemical does affect other aquatic life.

11. Feral Hog (Sus scrofa)

Feral hogs are found in the region between Texas and South Carolina, but it’s reported that they are known in around 40 states and 54 countries around the world. In North America numbers appear to have grown rapidly since the year 2000. That said, this species was first introduced in the 1500s by settlers who brought them for their meat. 

One of the biggest problems with the species is that they are known to carry a whopping 30 diseases as well as almost 40 different parasites. Not only can these diseases affect livestock which has a direct impact on farming, they’re also known to infect humans. Controlling these diseases, such as pseudorabies, is costing the US economy greatly. In the course of 17 years, more than $250 million dollars was spent on this alone.

Each state has its own methods of eradicating feral hogs, which is essential since they’re not only disease-ridden but they’re known to cause damage to agricultural land and private property as they dig for food. Moreover, they’ve had a serious impact on the ecosystem, altering it with their mere presence, including infecting water systems and altering biodiversity. If that wasn’t enough, it’s reported that these pigs release more carbon into the atmosphere than 1 million cars! 

12. Giant African Snail (Lissachatina fulica)

The giant African land snail is a popular exotic pet that originally comes from moist areas south of the Sahara desert. However, in 1966, all it took was one child to bring back three snails from his vacation and, all these years later, they’re a big problem in Florida.

It is reported that just seven years after the initial introduction of these snails, more than 18,000 were found in the wild, as well as a worrying number of eggs. While you might not think that a snail could do much damage, this species often attaches itself to concrete structures, like houses, in order to sap out calcium. The result of this is a weakened building structure. On top of this, the species is known to feed on more than 500 species of native plants. 

Several attempts at pest control are being undertaken to cull the populations of the giant African land snail. One such attempt was successful, and while it took ten years and $1 million, all specimens were eradicated. Sadly, the species was reintroduced in 2011, and the problem persists. Because of this, certain areas of Florida have been quarantined and it is illegal to move GAS from these areas. 

13. Asian Longhorn Beetle (Anoplophora glabripennis)

Asian longhorn beetles are primarily found in host trees such as maple and, as such, several industries have already been affected. These include the maple syrup industry, tourism, and the lumber industry and it’s estimated that, along the east coast of North America, $41 billion has already been lost to these bugs.

These beetles were first noted in the United States in 1996, and it’s suspected that the species made its way here in wooden shipments from East Asia.

The concern is not only an economical one but also an environmental one. Asian longhorn beetles are known to take up valuable habitat of native species, and while around $100 million per year is being spent in Massachusetts alone, the beetles remain a problem.

14. Northern Giant Hornet (Vespa mandarinia)

Native to east, south, and southeast Asia, the northern giant hornet (once known as the Asian giant hornet) has become something of a fear for people in North America. But there has been a lot of unnecessary media hype about these flying insects, which has instilled many incorrect ideas. The reality of the situation is that some northern giant hornets were found in BC Canada back in 2019, but the population was quickly destroyed. 

Since then, a few more isolated individuals and small nests were found just south of the Canadian border. However, according to reports, this is not evidence of a serious invasion just yet. Moreover, all of the hornets that were discovered were within a 50 mile radius and no further south than Washington.

It’s thought that the hornets got her through separate shipments from Asia, but authorities have jumped into action asking the public to report any sightings. Regular monitoring and the trapping of these insects is hoped to be enough to prevent an outbreak and of course, the conditions in this area are not conducive to the hornets’ survival.

That said, if populations were to grow, the concern is that the species would quickly take over the local bee populations. But this isn’t through taking their resources, rather the northern giant hornet is known to murder its fellow apian species!

15. Red Lionfish (Pterois volitans)

I’ll be the first to admit that the red lionfish is one of the most stunning aquarium pets. But, aside from their native habitat in the Indo-Pacific region, the fish tank is where they should stay because they’re a real threat to North American marine life.

These fish are at the top of the food chain under the ocean. Not because they’re voracious killers like orcas or sharks but because they are venomous marine creatures. This allows them to thrive and, in North American waters, they’re successfully competing for resources with our native species.

It’s believed that red lionfish found their way into North American Atlantic waters via accidental releases from pet owners. The problem began in the 1980s, but things have particularly escalated in the last 15 or so years. What’s really interesting is that the red lionfish appears to be a hybrid of two species from the Indo-Pacific region.

So, how are humans looking to deal with this invasion? Robots, of course! A team of scientists has developed two types of lionfish killing robots; one uses a spear to directly target individuals while the other has an arm which electrocutes the fish.

16. Red Eared Slider (Trachemys scripta elegans)

The red-eared slider is a species of turtle that is native to parts of the Midwest and northern Mexico. So, if it’s already a North American species, what’s the problem? Well, the issue is that this highly popular pet species has spread its distribution to many other areas in North America.

This is a problem because this species, much larger than many of the native species, easily outcompetes for resources. Not only this, but red-eared sliders also breed much more quickly and reach maturity far faster than native species. If that wasn’t enough to convince you that they should be removed, consider the fact that they carry a number of diseases that could upset the local ecosystem.

Since one of the major issues with invasive populations of red-eared sliders is due to pets being released into the wild, laws have been passed in Canada making it illegal to do so. In the United States, there are even programs designed to help rehome unwanted red-eared sliders, so if you have one then this is definitely a preferable option to releasing it.

17. Spotted Lanternfly (Lycorma delicatula)

As things stand, the spotted lanternfly has invaded the Northeastern parts of the US as well as the Mid-Atlantic region since 2014. However, these are such determined creatures that there is concern of them spreading further west.

If you’re keen to keep hold of your favorite crops, then there’s unfortunately no other option than to kill the spotted lanternfly on sight. These pests have been known to devour various crops, including apples, hops, grapes, and many tree species. The US officials are now advising that anyone stumbling upon one of the flies should kill it immediately. 

This might seem harsh as these are actually beautiful creatures, and while they thrive in Asia, in North America, they pose a serious risk to the logging and agricultural industries. Further action has been taken to prevent more populations being accidentally introduced. For example, in Pennsylvania, where the first spotted lanternfly was seen, transport that could possibly contain egg masses has been banned from entering the area.

Can Some Invasive Animals Be Beneficial?

When we talk about native species, it’s easy to feel threatened by them. In a lot of cases, they do more harm than good, but as with everything, there’s always a plus side.

One thing to keep in mind is that, while some invasive species can take over ecosystems and even cause the extinction of native species, this isn’t always the case. In fact, the introduction of some alien species isn’t always classed as an invasion, particularly if they do not have a negative impact on the local environment.

There are even some cases where alien species benefit the local ecosystem. But how can this be after everything we’ve discovered so far?

Just look at the honeybee; this is a species that was first introduced from Europe in the 17th century. While it’s not a native species, it has done wonders for crop production thanks to how well it pollinates. In fact, around 75% of all human crops in North America are pollinated by honey bees, and without them, we’d see a marked difference. 

What’s more, without the honey bee, the US economy would take a massive hit. It’s estimated that up to $577 billion worth of revenue globally comes directly from bee pollination.

Another species that isn’t native to all of North America is the earthworm. However, its presence within an ecosystem boosts agricultural productivity so, while it’s not natively found in the Midwest, it’s certainly welcome there.

On the other side of the world, in Australia, the crocodile is a native species whose numbers started to dwindle in the 1970s. However, with the introduction of the feral hog, crocodiles began thriving again, and it’s thought that this was because the pigs served as prey.

As you can see, the introduction of new species isn’t always a threat, although it still pays to be mindful about the effects these creatures could have. Control and management programs are essential, and if you ever see a non-native species, it may be worth reporting it to your local wildlife authority.