Invasive species in Hawaii facts for kids
Hawaii is a beautiful group of islands, but it faces a big challenge: invasive species. These are plants, animals, or other living things that are brought to a new place, often by humans. They can cause a lot of harm to the local environment and the unique plants and animals that already live there.
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Hawaii's Past: New Species Arrive
Because Hawaii is made of islands, most of its plants and animals either flew, swam, or floated there, or were brought by people. Over time, some of these new arrivals caused big problems.
Mongoose: A Failed Plan
In the mid-1800s, people brought mongoose to Hawaii. The idea was to control the many rats in the sugar cane fields. But mongooses hunt during the day, and rats are active at night! So, the mongooses didn't really help with the rats. Instead, their population grew, and they started eating the eggs of ground-nesting birds, causing their numbers to drop.
Fire Tree: A Pretty Plant, A Big Problem
The fire tree was brought from other islands in the 1800s. It was used as an ornamental plant (for decoration) or for firewood. But now, this small shrub is a serious threat to Hawaii's native plants. It grows very thickly, forming dense patches where nothing else can grow.
Strawberry Guava: A Tasty Fruit, A Tough Invader
The strawberry guava was introduced in the early 1800s because it had tasty fruit. But this plant has become one of Hawaii's worst invasive species. It grows into thickets that block sunlight from native plants. Its roots also spread widely, taking up water and nutrients that native plants need.
How Invasive Species Harm Hawaii
Invasive species can hurt Hawaii's environment in many ways. They can bring diseases, act as predators, compete for food, change habitats, or even mix with native species.
Diseases from New Species
Invasive species often carry new diseases that native plants and animals have never seen before. For example, tiny mosquitoes were brought to Hawaii. They spread diseases like avian malaria to native birds. They also increase the risk of diseases like dengue for humans.
Native trees are also at risk. The once-common koa tree is being killed by koa wilt. Scientists believe this disease came to Hawaii on another ornamental plant. The important 'ohi'a tree is also suffering from a new disease called Rapid Ohia Death.
New Predators in the Wild
When invasive predators arrive, native animals often don't know how to defend themselves. This is because they didn't evolve with these new threats. These new predators can greatly reduce the numbers of native species, sometimes even causing them to disappear completely.
Competition for Resources
Often, introduced species are better at surviving than native ones. They compete for food, water, and space. The strawberry guava is a good example. It crowds out native plants, harms natural areas, and even changes how ecosystems work, like water production. It also provides a hiding place for alien fruit flies that harm Hawaiian agriculture.
Changing the Environment
Invasive species can change an environment in many ways. How they eat and interact with their new surroundings can limit the amount and type of resources available for native species. This can make it hard for native species to find what they need to survive.
Mixing Genes: Hybridization
Hybridization happens when two different species mate and have babies that carry genes from both parents. If an invasive species is much more common than a native one, they might mate so often that the native species' genes get "flooded out." This can lead to the native species effectively disappearing. For example, the native Hawaiian duck (koloa maoli) is threatened by mating with introduced mallards.
Impacts on Hawaiian Culture
In Hawaii, the local culture is deeply connected to its environment and native species. Chants, ceremonies, and hula often use native plants. Invasive species can directly affect these practices. For instance, taro (kalo) is a sacred plant in Hawaiian culture, believed to be the ancestor of the Hawaiian people. The golden apple snail, an invasive species, attacks taro plants, threatening this important cultural symbol.
Threats to Hawaii's Natural World
Hawaii faces a growing crisis from invasive species. These invaders threaten endangered plants and animals, human health, and important parts of Hawaii's economy like tourism and farming. Islands are especially vulnerable to invasive species.
Invasive Aquatic Species
Hawaii's coral reefs are very important for tourism, bringing in millions of dollars. But invasive species threaten them. Freshwater invasive species are also a problem. In 2003, Lake Wilson was taken over by an invasive floating fern called Salvinia. This fern competed with native species and fish, costing the state over $1 million to clean up.
Other fish have also spread in Hawaii's freshwaters. Sport fishermen introduced species like trout and bass. People also released pet fish like guppies, suckermouth catfish, and swordtails into local waters. Suckermouth catfish dig into the ground, harming local wildlife. Even seemingly harmless guppies can spread diseases to native gobies.
Invasive Insects & Spiders
Insects can have a huge impact on Hawaii's environment, crops, and human health.
- Little Fire Ants: Populations of little fire ants can cause painful stings and attack in swarms. They harm animals, crops, and humans. These ants came to Hawaii on imported plants.
- Coffee Berry Borer: The coffee berry borer is a major threat to Hawaii's coffee crops. It can destroy entire harvests. Farmers are trying to fight them with pesticides, but some borers are becoming resistant.
- Coconut Rhinoceros Beetle: The coconut rhinoceros beetle was first found in Hawaii in 2013. This large beetle eats the growing shoots of coconut trees, damaging them and making them sick.
- Small Hive Beetle: The small hive beetle is destroying bee hives and honey production across the islands. This harms not only commercial honey but also wild bee populations, which are vital for pollinating plants.
- Spiders: Several invasive spiders, like the brown widow spider, brown violin spider, Asian spinyback spider, and pale leaf spider, have also made their home in Hawaii. They often arrived by hiding on bananas from tropical regions.
Invasive Land Animals
On land, invasive animals are a big problem in Hawaii because the islands don't have many natural predators to control them. These invaders often become top predators, harming populations of small mammals, birds, insects, and plants.
- Chameleons: The veiled chameleon and Jackson's chameleon were brought to Hawaii through the pet trade in the 1970s, even though it was against the law. They eat insects, leaves, flowers, and even small mammals and birds. They greatly harm Hawaii's ecosystems because they have no natural enemies and can adapt to many different conditions.
- Coqui Frogs: The coqui frog is another threat. It makes very loud noises, eats native insects, and could become food for the dangerous brown tree snake.
- Brown Tree Snake: Hawaii is working hard to prevent the brown tree snake from invading. This snake has caused huge problems in Guam, destroying bird, bat, and lizard populations. It also causes power outages by climbing electrical wires. If it gets to Hawaii, it could cost the state millions of dollars. There is a big fear that these snakes could arrive on cargo ships from Guam.
- Feral Pigs: Feral pigs, which are wild pigs that escaped from farms, are a major threat. They destroy plants and habitats, and their digging harms bird nesting grounds and causes soil erosion. In remote areas, they destroy the nests of seabirds like the Newell's shearwater and Hawaiian petrel. Their burrows also create dirty pools of water where mosquitoes breed, spreading diseases that kill native Hawaiian birds.
Economic Impact of Invasive Species
Invasive species cause serious financial harm to many of Hawaii's industries.
- Taro Crops: Non-native snails, insects, and viruses have threatened the taro root crop, which is a $2 million industry. The taro aphid can destroy 90% of a crop. To fight it, farmers sometimes have to remove all taro from an area for a year, which is a huge loss.
- Papaya Industry: The papaya industry, worth $16 million annually, has been hit by the Papaya ringspot virus, which kills trees and ruins fruit. Also, fruit flies have led to restrictions on trade with places like Japan and California, costing Hawaii an estimated $300 million in lost sales.
- Sugarcane and Macadamia Nuts: Since 1985, insect pests have cost the sugar cane industry over $9 million. Rats and rodents caused $6-10 million in damages to sugar cane in the 1990s. They also eat 5-10% of the valuable macadamia nut crop, causing millions of dollars in damage.
The introduction of mongooses to control rats didn't work and harmed native birds. Similarly, the Indian myna bird was brought in to fight sugar cane worms, but it accidentally helped spread an invasive weed called Lantana camara. These examples show how difficult it is to fight invasive species and how quick solutions can have unexpected bad effects.
Fighting invasive species is a constant concern for Hawaii's government. It would take about $50 million each year to fully deal with the problem, but current funding is much lower. Because of the high costs, the government is focusing on preventing new invasions and finding steady funding sources.
Hawaii Invasive Species Council (HISC)
In 2002, a report showed the funding gaps and risks from invasive species. In response, the Hawaii Invasive Species Council (HISC) was created. The HISC brings together different state departments, like Land and Natural Resources, Agriculture, and Health, along with the University of Hawaii.
The HISC helps guide, coordinate, and plan efforts to control and get rid of invasive species. It works to prevent new invasions, detect them early, respond quickly, and control existing pests.
HISC also partners with Island Invasive Species Committees (ISCs) on each island. These committees, like KISC (Kauai), OISC (Oahu), MISC (Maui), MoMISC (Molokai), and BIISC (Big Island), work to protect their specific island from invasive pests. They use prevention, early detection, quick response, and control methods. Their goal is to protect farming, water sources, human health, Hawaiian cultural practices, and Hawaii's unique biodiversity.
Currently, HISC's funding has been cut due to economic challenges, which affects the effort to fight invasive species in the state.
