Non-native Species

Mammoth Cave National Park is home to a plethora of native plants and animals. The park is also known for its diversity of habitats and ecosystems. Alongside the native biota there are non-native and invasive plant and animal species that threaten the existence of these delicate native ecological habitats.

 

Key Terms

Native Species: An organism that is native to an area is there because of reasons unrelated to human intervention. It may have evolved there or may have been moved there by natural causes.

Non-native Species: A non-native species is one that has been introduced to an area deliberately or accidentally. They are sometimes referred to as exotic species. Non-native species are not always considered nuisances. 

Invasive Species: An invasive species is a non-native species introduced to an area that becomes overpopulated and negatively alters its new environment by outcompeting native species and replacing them. 

 

A European starling at Cuyahoga Valley National Park.

NPS photo/Schmidt

Where do Non-native Species Come From?

Non-native species can be transported and introduced from one area to another from a variety of movement methods. Wind and water are often thought of as primary movers of seeds and spores, but humans can play a large role as well.

Seedlings stuck to hiking boots or attached to clothing can be moved by hikers hundreds of miles. Aquatic species can cling to ships hulls, anchors, other equipment or be sucked up in bilge water, allowing for the potential movement of thousands of miles around the globe. Even the intentional movement of plants and animals for commercial purposes such as agriculture can unintendedly move non-native species to new regions of the world.

The movement of non-native species is not new to the modern world. At the time of European colonization of North America, hundreds of species were brought to the new world. People like Thomas Jefferson introduced many plants from other countries to the United States. Even commonly seen species like the European starling, which is now numbering in the millions across North America, were introduced by Eugene Schieffelin in 1890 to share the birds of Shakespeare with the United States.

Examples of Non-native Species Found in the Park

 

An emerald ash borer feeds on an ash leaf in USDA FS Northern Research Station.

Photo by Leah Bauer

Animals

Feral cats Felis catus and domestic dogs Canis familiaris

Feral house cats and dogs running loose in the park have been known to prey upon small animals that make the forests of the park their home, such as moles, voles, chipmunks, squirrels, and even birds and bats. The abandonment of cats and dogs within Mammoth Cave and other national parks has become an increasingly important issue that park resource managers and law enforcement are working to address.

Wild boar Sus scrofa

Wild boar have been found in the park and removed by park scientists. These feral hogs can destroy native plant communities by rutting up large areas of the soil, while also breeding profusely. Park resource managers must be vigilant in capturing these exotic animals before they can destroy the local habitats and its inhabitants.

Insects

Emerald ash borer Agrilus planipennis

The emerald ash borer (EAB) is a jewel beetle native to north-eastern Asia that feeds on ash species. EAB has recently been identified in the park, the impact of this species will kill most of the ash trees found in the park, consisting of the loss of thousands of individual ash trees. Since its discovery in the United States in 2002, EAB has killed millions of ash trees all over the eastern United States. Governments in North America are taking steps to control it by monitoring its spread, diversifying tree species, and using insecticides and biological control.

 

Fungus

Chestnut blight Cryphonectria parasitica

Chestnut blight is a parasitic fungus that infects several tree species, such as the American chestnut, in North America and Europe. The fungus is native to Asia and was introduced in the early 1900s from the cultivation of trees for commercial purposes. It is estimated that the chestnut blight killed approximately 3.5 billion trees from the first half of the 20th century through 2013.In the past, some of the estimates of chestnut trees in certain areas the park’s forest were equal to approximately 25% of the forest canopy, today that number is closer to 0.5%.

White-nose Syndrome Pseudogymnoascus destructans

Pseudogymnoascus destructans is a cold-loving fungus that causes the disease White-nose Syndrome (WNS) in bats. The fungus originates from the European continent and was unknown to North America until a bat infected with WNS was first discovered in New York in 2006.

Since its discovery in North America, WNS has quickly spread across the continent and is now found from coast to coast. In some cases, bat species infected with WNS have seen mortality rates over 90% within five years for the disease reaching the site.

Learn more about White-nose Syndrome and efforts being taken to slow its spread.

 

Garlic mustard (Alliaria petiolata)

NPS Photo/ Deb Spillman

Plants

Of the thousands of species of plants that take up residents within the boundaries of the park, over 170 species are considered non-native. Of those 170 species, over 100 are considered invasive and can take over an area very quickly and easily. Over 60 of these species are considered “significantly to seriously invasive” in the state of Kentucky.

Japanese Chaff Flower Achryanthes japonica

First identified in Kentucky in 1981, this invasive plant from eastern Asia spreads quickly along riverbanks, roadsides, trails, and bottomland forests. The seeds of this plant attach easily to clothing and fur, allowing people and animals to spread them inadvertently.

Kudzu Pueraria montana

Native to Asia, Kudzu is considered highly invasive in North America. This vine can grow up to one foot per day and has earned the nickname of “the vine that ate the South”. When growing unhindered, Kudzu can overtake all native plants, shading them, and growing completely over trees in an area. Usually, cold winter temperatures have helped reduce the growth rate of kudzu within the park, but climate change has worked in favor of this invasive species.

Garlic mustard Alliaria petiolata

Garlic mustard was introduced to North America by way of European settlers in the 1800s for culinary and medicinal uses. It is native to Europe, Asia, and Northern Africa. In North American forests, garlic mustard can dominate the understory by outcompeting native species and releasing an enzyme into the soil that prevents other plants from sprouting. This combination can result in the reduction of biodiversity forest understory plants in many areas.

 

Park resource managers work with volunteers to remove garlic mustard during annual volunteer events.

NPS Photo

What is the Park Doing About it?

Non-native and invasive animal and plant species can change the structure of an entire area. Native flowers, that draw people to the park, can be replaced by plants from a totally different continent. In North America, introduced species from other continents can grow unhindered, whereas in their home region there are animals and other factors that are able to keep the numbers at low levels.

It is our native plants and animals that draw people to the outdoors. With the spread of invasive species our park lands may come to look like another country. Controlling the invasion of non-native species in order to protect our native species is a daunting task for anyone. Resource managers at the park continuously look for new ways to combat the influx of non-native species, utilizing methods such as:

• Hosting volunteer events to pull garlic mustard from the forest floor
• Establishing decontamination procedures for exiting the cave to slow the spread of white-nose syndrome

You can also help slow the spread of non-native and invasive species in the park by looking for volunteer opportunities and by learning more about Non-native and invasive species throughout the National Park System.

 

Park Species List

Explore a sortable database of species found in the park.

NPSpecies