Invasive Species

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Podcast Transcript

Places all over the world are suffering from a similar ecological problem. 

The specific problems are slightly different everywhere, but they all are based on the same fundamental issue: Invasive species.

How each invasive species got where they are is a different story. Regardless of how they got there, some species can wreak havoc on an ecosystem once introduced.

Learn more about invasive species and the damage they have done on this episode of Everything Everywhere Daily.

Growing up, I was aware of certain invasive species. Where I lived in Wisconsin, there were often warnings given to people with boats that they had to clean off their boats when they took them out of the water to prevent the spread of zebra muscles. 

We also had a problem with a species known as the gypsy moth, which has spread across the United States over the last 150 years. 

Both of these were things that I heard of on the news, but they really didn’t have any day-to-day effect on me. 

The thing that really hammered home the problem of invasive species was my first trip to Australia. In addition to the typical passport control you have to go through, Australia also requires you to go through a very thorough inspection of what you are bringing into the country. 

They prevent you from bringing almost any food, especially any fruits or vegetables. They can ban hiking boots if they aren’t clean enough and have been used recently. If you travel with a dog or cat, they will probably have to sit in quarantine for up to a month. Other pets may not be allowed in at all. 

Having gone through the process, I found the biological inspection to be more thorough than the process of checking my passport. When I was done, I was curious just what the big deal was and why Australia was so worried about letting biological material into the country. 

It turned out that they had a good reason to be concerned. Australia, perhaps more than any other country, has suffered greatly at the hands of invasive species. 

Before I get into that, I should probably back up and explain what invasive species are and what exactly the problem is. 

An alien species is any species that is not native to a particular region. Alien species are not inherently bad. For example, almost all agricultural crops are alien species. 

An invasive species is an alien species that can cause great harm to the environment, usually because they fill a role in the ecosystem where they can out-compete native species or because they have no natural predators. 

So, wheat is an alien species, but it isn’t an invasive species. We don’t have a problem with wheat growing everywhere and choking forests to death because there is so much wheat being grown. 

In many cases, an alien species might be introduced, which is totally unsuited for a particular environment, and it dies off quickly. To propose an extreme example, think of what would happen if you put a polar bear in the African savannah. 

As fearsome as polar bears are as predators, it is unlikely they will make it in an environment so different from the one they are adapted to. 

The problem of invasive species has to do with evolution. 

Over long periods of time, every ecosystem will develop an equilibrium of the species that live there. All the plants and animals will develop adaptations that allow them to fit and survive. If they can’t, they won’t survive. 

In the Eastern hemisphere, that being all of Africa and Eurasia, you had a massive landmass with countless species, which made for very robust ecosystems. 

However, consider an island in the Pacific Ocean like one of the Hawaiian Islands. Created by a volcano, it may have taken thousands, if not millions, of years for the island to have been populated with plants and animals. Birds would land on it during their migrations, bringing with them seeds from their previous location.

Storms would blow debris onto the island, which might bring insects and occasionally small lizards onto the island. Other non-migratory bird species might be accidentally blown there during a storm.

Every so often, a new species might appear in an ecosystem. What happens will result in how that particular species react to the ecosystem it finds itself in. 

While this can occur naturally, it is very difficult to do. An insect or a bird might be blown across a large body of water, but a mammal would be near impossible. That is why there are no native mammals on any Pacific island, save for a species of bat known as flying foxes. 

Humans, however, are capable of bringing larger animals long distances and transporting them, either accidentally or on purpose, to places they never were before. 

Early human seafarers just kept to the shore and traveled to places with somewhat similar ecosystems. A Chinese trader might go up and down the coast of China or Southeast Asia, and any species they brought with them probably could have made it there on their own. 

Traders in the Mediterranean were mostly moving between ports with a similar climates. 

Everything changed when ships started sailing across oceans and began visiting the Americas and smaller, more remote islands. 

Probably the first species which was brought across the ocean to be considered invasive were rats. 

Rats had plagued sailing ships for centuries. They were unwanted passengers that would feed on the food stores on a ship. 

When a ship arrived at an island, it would usually anchor off the shore and take a smaller ship to land. That prevented most rats from leaving the ship. But eventually, ports were built which allowed rats just to walk off the ship. 

Some shipwrecks would wash up on the shore of an island, bringing rats with them. 

In a previous episode on the rats of South Georgia Island, I explained the problem with rats. They are omnivorous creatures that reproduce rapidly. A single pair of breeding rats can result in half a billion rats within three years.

Rats can devastate the populations of almost any animal on an island that has no defense, including most reptiles, amphibians, and birds. They can also consume nuts, making it difficult for many plant species to reproduce. 

Today, the brown rat, or Norwegian rat, can be found on every continent except Antarctica and in almost every urban area. Despite its name, it actually is believed to have originated in Asia. 

The palace which has done the best job of eliminating rats is the Canadian province of Alberta.  Alberta is considered to be the world’s largest rat-free zone today. 

Their efforts began in the 1950s as rats can’t survive outside in the winter in Alberta, they have to winter in buildings. They have been able to target their efforts, and since 2003 they have regularly had years with zero rat infestations, which is defined as any sighting of two or more rats.

While rats were brought accidentally, many invasive species were brought on purpose, often for noble intentions. 

In 1859, a man named Thomas Austin, who lived in Victoria, released 24 rabbits and let them run around on his estate.  He was quoted as saying, “The introduction of a few rabbits could do little harm and might provide a touch of home, in addition to a spot of hunting.”

Within 50 years, those 24 rabbits had grown to millions of rabbits and had inhabited most of the country. 

The problem with rabbits in Australia is that there really is no apex predator in Australia to keep their population in check, and the fact that rabbits breed like…..well, rabbits. 

The rabbits began devastating farms, wiping out crops. In 1887, the Inter-Colonial Rabbit Commission offered a £25,000 prize “to anyone who could demonstrate a new and effective way of exterminating rabbits.”

It eventually led to the creation of the rabbit-proof fence in Western Australia, which is one of the longest fences in the world. 

Rabbits are far from the only invasive species in Australia. Another major problem is the cane toad. 

The cane toad is native to Central and South America. It was introduced to Australia in 1935 via Hawaii with the intent of keeping insect populations infecting sugar cane crops in check. 

They pretty much failed at their mission of eating the beetles that attacked sugar cane, but they did spread rapidly. From their initial release in Northern Queensland, they have been spreading outward ever since and have now reached New South Wales and the Northern Territory. 

In addition to simply out-competing other native species, cane toads are poisonous, meaning the predators that do eat cane toads often die. 

Even camels have become feral in the Australian outback. Originally brought to Australia to carry supplies through the desert, there are now several hundred thousand feral camels that roam the interior of the country. 

The impact of camels isn’t as bad as other species introduced to Australia, but it shows that it isn’t just small creatures that can be invasive.

The State of Florida sufferers from several invasive species, and their introduction came in a very different way. 

Southern Florida has seen an invasion by Burmese Pythons. Giant snakes that grow up to 18 feet or six meters long and weigh up to 200 pounds or 90 kilograms.

How did giant snakes get transported from Southeast Asia to Florida? The answer is exotic pets. People get pythons as pets because they think it would be cool, but eventually, they get too big, and they can’t keep them anymore, so they do what they think is the humane thing and release them into the wild.

Once in the wild, they will breed and pretty much eat anything and everything. 

Pythons aren’t the only problem. There is a concern that Nile Crocodiles could become established in Flordia. These are far more deadly than their North American counterparts. 

Lionfish have become a huge problem in the coral reefs around Florida. They hail from the Indo-Pacific and were shipped as part of the aquarium trade. Here too, at some point, someone thought they were doing the right thing by letting them free. In reality, they are very poisonous and have no natural predators. 

Many SCUBA divers in Florida will now dive with a speargun just to shoot any lionfish they might encounter. 

The Mississippi River and many of its tributaries are now suffering from Asian Carp. They were originally introduced in the 1970s to fish farms to keep them clean of algae. After the flooding of the river, many of the fish escaped and established a breeding population. 

They are huge fish that outcompete other native fish because they consume so much and breed so rapidly.

One concern is that they might travel up the Chicago Canal, which connects the Mississippi River to Lake Michigan. 

In 1946, the Argentine government brought North American beavers to Patagonia to create a fur industry. The plan backfired dramatically, and now there are beaver-created dams and flooding areas that were never designed to experience flooding. 

They have spread to Chile and are causing problems all over Tierra Del Fuego National Park.

Invasive species don’t just go from the old world to the new. It can go the other way as well. 

The brown tree snake, which is native to Australia, was introduced to the island of Guam, where it has caused huge problems.

North American raccoons were brought to Europe to create a fur industry and later escaped. There are now millions of them across the continent. In Japan, a popular cartoon named Rascal the Raccoon resulted in 1,500 raccoons being imported to Japan for people to keep as pets. 

Needless to say, they make horrible pets, and now they are all over Japan. 

Largemouth bass are popular sport fish in North America. They were introduced all over the world and can now be found in Africa, Europe, New Zealand, Japan, China, and South America. They are carnivorous fish that eat other fish as well as any other creature they have to come across.

You might be thinking that the solution to many of these invasive species is to bring in another species that would prey on them. Well, that’s been tried, but the result is almost always not was is desired. Cats have been brought in to kill rats and rabbits, but they often just hunt native animals, which are easier, and have no fear of cats. 

Almost everything has been tried to get rid of invasive species, including poisoning, traps, hunting, and bounty programs. Save for small areas like islands or places with unique environments, most programs to remove invasive species don’t work.

One promising technique that might have problems all its own is genetically engineering versions of invasive species that can only produce males. These males can then only produce males, and so on and so on. If released into the wild, they could eventually eliminate the population by making it impossible to reproduce.

At some level, invasive species is a problem that will never go away. We can’t put the genie back into the bottle.

We are much more aware of the problem than we were just decades ago, and the idea of releasing alien animals into an ecosystem is seldom done anymore. However, there are so many invasive species that, in many cases, are so well established that it might be impossible ever to remove them. 

So, if you ever visit Australia or another island country and you have to go through some sort of biosecurity control, just keep in mind that there is a pretty good reason why they do it.

The Executive Producer of Everything Everywhere Daily is Charles Daniel.

The associate producers are Thor Thomsen and Peter Bennett.

Today’s review is a re-review from Apple Podcasts in the United States. Listener “Disappointed and Confused” updated their review that I read several episodes ago. They now write:

I would like to go on the record as saying that I am very ashamed that I missed your correction about Anchorage. I am truly sorry about my last review. Over the course of the last year, my wife and I have had so many amazing conversations because of your podcast, we both feel like you are a friend of the family, Gary, and we both apologize sincerely. We hope everyone listens to this show, anywhere they are, every day. Thanks again Gary, you’re amazing.

Thanks, Disappointed and Confused! You know what. Don’t worry about it. Everyone makes mistakes. I made a mistake, which was the impetus for your first review. I think acknowledged the mistake and corrected it. You acknowledged your mistake and corrected that. 

That is the best we can do. Acknowledge our errors and then move on. 

Remember, if you leave a review or send me a boostagram, you too can have it read on the show.