National Invasive Species Awareness Week runs February 22-28, 2021. But what does that mean? What are invasive species and how do they impact our local habitats? Let’s take a closer look.
What is an “invasive species”?
An invasive species is a plant or animal that 1) is not a native species — it was brought into a habitat that it is not originally from, and 2) negatively affects that habitat.
Are all non-native species invasive? No, actually! First, let’s think about what makes up a habitat. All the plants and animals in an area originally, these native species, interact with each other and many have relationships. All species need resources for life, such as a place to live (a nest, a burrow, a leaf for eggs) and food. For instance, insects pollinate plants, and in turn are eaten by frogs, birds, and rodents. Larger birds and mammals feed on smaller ones. Certain plants grow in certain kinds of soil. Everything is interconnected.
When a new plant or animal is introduced into this habitat, they also need resources. Sometimes, a non-native species enters an ecosystem or habitat and causes very little disruption; then scientists call it an introduced species. Other times, it may directly compete for resources with a similar native species. Perhaps they like the same kind of nesting place, or the same food. This non-native species may have some advantages too. It may not have any predators in this new place. It may grow faster or be larger than the native species. If the non-native species overtakes the native species for those resources, or takes over a habitat, it disrupts the native habitat. It is then identified as an invasive species.
Are there invasive species in Illinois?
Yes, there are many plant and animal species that have been introduced to Illinois and are invasive. As people’s ability to travel and transport goods becomes easier, it also becomes more difficult to control the transfer of plants and animals from one geographic location to another. Below are a two examples of invasive species in Illinois. Check out the Illinois Invasive Species website for more information.
European starling (Sturnus vulgaris)
European starlings are native to Europe, East Asia, and northern Africa. They were purposely released by a group of people into Central Park in New York City. Their goal was to see the plants and animals mentioned in Shakespeare’s works in the “new world”. The birds were first released in 1890 and it actually took several attempts before the species survived. It is estimated that in about 1907 the species started spreading. Today, this species is found across North America.
Starlings are often found in flocks and can be seen in fields or roadsides hunting for insects in the ground. They are cavity dwellers, so build their nests inside holes of trees and such, and eat insects, fruits, and grains. They have proven themselves to be highly adaptable to many habitats, as they are now so widespread. They compete with native species of birds for nesting sites and food. They can be aggressive and have been known to push other species out of a nest they want to use, even birds that are larger than they are! Learn more.
Zebra mussel (Dreissena polymorpha)
Zebra mussels are a freshwater bivalve native to Europe and western Asia. This species is considered one of the worst invasive species as it has been spread around the world through the ballast water of ships and boats. First discovered in North America in Lake St. Clair (which sits on the border between Canada and the United States) in 1988, this species is now prolific in the Great Lakes and in many river systems in the Midwest and Northeast United States.
Zebra mussels are filter feeders of the tiny phytoplankton that form the base of the food web, and each one can filter a liter of water per day. There are currently so many zebra mussels in Lake Michigan that they can filter the entire volume of the lake in four to six days, leaving little food for native filter feeders. The clear, blue water of the lake on sunny days looks beautiful, but that clear water indicates a lack of phytoplankton as food for native species.
As well as disrupting the food chain, zebra mussels can cause major infrastructure issues. They attach to hard surfaces throughout the lake, including docks, piers, screens, and pipes. If enough zebra mussels become attached to water intake pipes, like those going to the water treatment plants, the pipes can become clogged, which can cause major issues. Zebra mussels also attach to boats and spread to other bodies of water if the boats are not properly cleaned and drained. Learn more.
How are natural history museums helping?
Natural history museums like the Nature Museum document the natural world. Regional scientific collections, like ours, focus on the plants and animals found in the local area, and can provide a record of the species that are found here through time. Documenting non-native species that appear in the region can provide information about when that species started showing up, how it spread, and where it was found. Observing and documenting nature allows us to study changes in the local environment and share this information with other scientists, governmental agencies, and communities.
It’s not just physical specimens that are important in our analysis of the environment either — other kinds of materials in museums and archives can provide information too! In the Nature Museum’s collections, historic photographs provide visual evidence of the presence, or lack thereof, of a species in an area. Naturalists’ field notes and maps recording observations can provide a first-hand account of that time period.
Nature Museum biologists work closely with local endangered species, and part of that work entails trying to remove non-native species when possible. Dr. Allison Sacerdote-Velat has studied the effects of buckthorn on the growth and development of frogs in Illinois’ wetlands. Around the grounds at the Nature Museum, staff remove non-native plants and periodically burn the prairie, which allows native plants to take hold and flourish.
Learn how our manager of horticulture cares for the Nature Museum grounds, and how we work to allow native plants to thrive, by checking out the episode of Curious By Nature below.
You can also learn more about how collections can inform and impact restoration efforts in this webinar featuring our senior director of collections, Dawn Roberts.