Everything Everywhere Daily: History, Science, Geography & More - Invasive Species

Starting point is 00:00:00 Places all over the world are suffering from a similar ecological problem. The specific problems are slightly different everywhere, but they're all based on the same fundamental issue. Invasive species. How each invasive species got where they are is a different story, but regardless of how they got there, some species can wreak havoc on an ecosystem once introduced. Learn more about invasive species and the damage that they've done on this episode of Everything Everywhere Daily.

Starting point is 00:00:26 What if your perceptions about the past were wrong? long. ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR. 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 their boats off before they took them out of the water to prevent the spread of zealine. zebra muscles. We also had a problem with a species known as the gypsy moth, which had spread across

Starting point is 00:01:21 the United States over the last 150 years. Both of these were things that I had heard of in the news, but they didn't really 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're bringing into the country. They prevent you from bringing in almost any food, especially fruits or vegetables. They can ban hiking boots if they aren't clean enough and have been recently used. If you travel with a cat or a dog, they'll probably have to sit in quarantine for up to a month, and other pets may not be allowed in at all. Having gone through the process, I found the biological

Starting point is 00:02:04 inspection to be more thorough than the process of checking my passport. When I was done, I was curious as to 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 causes great harm to the environment, usually because they fill a role

Starting point is 00:02:51 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's not an invasive species. We don't have a problem with wheat growing everywhere and choking forest to death because there's so much wheat being grown. In many cases, an alien species might be introduced, which is totally unsuited for a particular environment, and it quickly dies off. 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's unlikely that they will make it in an environment so different from the one that they're adapted to. The problem of invasive species has to do with evolution. Over long periods of time,

Starting point is 00:03:32 every ecosystem will develop an equilibrium of the species that live there. all of the plants and animals will develop adaptations that will allow them to fit and survive, because if they can't, they won't be there. In the eastern hemisphere, that being all of Africa and Eurasia, you had massive land masses 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,

Starting point is 00:04:09 bringing with them seeds from their previous location. Storms would blow debris onto the island, which might bring insects and rarely small lizards. Other non-migratory species of birds may accidentally be blown there during a storm. So every so often a new species may appear in an ecosystem. What happens will result in how that particular species reacts to the ecosystem it now finds itself in. While this can occur naturally, it's very difficult to do. An insect or a bird may be blown across a large body of water, but a mammal would be near impossible. That's why there are no native mammals on any of the Pacific Islands, save for a species of bat known as a flying fox. Humans, however, are capable of bringing

Starting point is 00:04:51 larger animals across long distances, and transporting them, either accidentally or on purpose, to places they never were before. Early human seafarers, is just kept to the shore and traveled to places with somewhat similar ecosystems. For example, a Chinese trader may go up and down the coast of China or Southeast Asia, and any species that they brought with them probably could have made it there in their own. Traders in the Mediterranean were mostly trading between ports with similar climates. But everything changed when ships started sailing across the oceans and began visiting the New World and smaller, more remote islands.

Starting point is 00:05:25 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 often feed on the food stores of 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 to just walk off the ship. Some shipwrecks would wash up on 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.

Starting point is 00:06:00 They are omniferous creatures that reproduce rapidly. A single pair of breeding rats can result in a half a billion rats within just 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, which is why there are no native trees on Easter Island. Today, the brown rat, or Norwegian rat, can be found on every continent except Antarctica and in almost every urban area. And oddly enough, despite its name, the Norwegian rat is actually believed to have originated in Asia.

Starting point is 00:06:38 The place 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 inside buildings. They've 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 by the name of Thomas Austin, who lived in Victoria, Australia, released 24 rabbits and let them run around his estate. He was quoted as saying,

Starting point is 00:07:22 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 200s of millions of rabbits and inhabited most of the country. The problem with rabbits in Australia is that there is really 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 and wiping out crops.

Starting point is 00:07:50 In 1887, the Intercolonial Rabbit Commission offered a 25,000 pound 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 1930s. 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,

Starting point is 00:08:30 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-toes are poisonous, meaning that predators that do eat cane-toes 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.

Starting point is 00:08:59 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 suffers from several invasive species, and their introduction came in a very different way. Southern Florida has seen an invasion of Burmese pythons. Giant snakes that can grow up to 18 feet or 6 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.

Starting point is 00:09:30 People get pythons as pet 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 Florida, and these are far more deadly than their North American counterparts. Lionfish have become a huge problem in the coral reefs off Florida.

Starting point is 00:09:59 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 spear gun just to shoot any lionfish that 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. But after flooding of the Mississippi 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.

Starting point is 00:10:39 One big concern is that they might be able to. travel up the Chicago Canal, which connects the Mississippi River to the Great Lakes. In 1946, the Argentine government brought the North American beaver 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've spread to chili 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's caused huge problems. North American raccoons were

Starting point is 00:11:18 brought to Europe to create a fur industry, and then later escaped. There are now millions of them across the continent. In Japan, a popular cartoon by the name of Rascal the Raccoon resulted in 1,500 raccoons being imported to Japan for people to keep as pets. Needles to say, they make horrible pets, and now they're all over Japan. Largemouth bass are popular sport fish in North America, but they were introduced all over the world and now can be found in Africa, Europe, New Zealand, Japan, China, and South America. They are carnivorous fish that eat other fish, as well as pretty much any creature they 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,

Starting point is 00:12:01 but the result is almost always not what was desired. Cats have been. been brought in to kill rats and rabbits, but they often just hunt native animals, which are easier to kill 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 South Georgia Island, or places with unique environments, most programs to remove invasive species don't work. One promising technique that might have problems all of its own is genetically engineering versions of invasive species that can only produce males. These offspring could only produce males and so on and so on.

Starting point is 00:12:40 If released into the wild, they could eventually eliminate the population by making it impossible to reproduce. At some level, invasive species are a problem that will probably 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 a few 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 they're so well established that it may be impossible to ever remove them. So if you ever do visit Australia or another island country and you have to go through some sort of biosecurity control,

Starting point is 00:13:16 just keep in mind that there's a pretty good reason why they do it. The executive producer of Everything Everywhere Daily is Charles Daniel. The associate producers are Thorpe Thompson and Peter Bennett. Today's review is a re-review from Apple Podcasts in the United States. Listener disappointed and confused updated the review that I read several episodes ago. They now write, I would like to go on record as saying that I am very ashamed that I missed your correction about Anchorage. I am truly sorry about my last review.

Starting point is 00:13:46 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 the show anywhere they are every day. Thanks again, Gary, you're amazing. Well, thanks, thanks, disappointed and confused. you know what, don't worry about it. Everybody makes mistakes. I made a mistake, which was the impetus for your first review.

Starting point is 00:14:10 I acknowledged the mistake and corrected it. You acknowledge your mistake and corrected it. And that's really the best we can do. We acknowledge our errors and then we move on. Remember, if you leave a review or send me a boostogram, you two can have it read on the show.

Everything Everywhere Daily: History, Science, Geography & More - Invasive Species

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