Many park units within the National Park System grapple with non-native plant and animal species, defined as having been introduced to an area as a result of direct or indirect, deliberate, or accidental actions by humans. Rocky Mountain National Park in Colorado is home to its share of non-native species, some of which can also be termed invasive species.
Why doesn’t the park call these non-native species invasive species? Aren’t they the same? Not exactly. While the terms invasive species and non-native species are often used interchangeably, there is a difference. Non-native species are any organisms not originally found in an area, while an invasive species is a non-native species that causes harm to the environment, wildlife, economy, or human health.
The National Park Service puts it this way:
Non-native species are plants and animals living in areas where they don't naturally exist. Often, they were intentionally introduced by humans, such as livestock or ornamental plants, but they could have been accidentally brought into new areas.
Domestic cows (Bos taurus) were brought to North America as a food source, and continue to be raised for meat and dairy products. Though they are not native to North America, they are considered a beneficial organism in an agricultural setting.
Bell peppers (Capsicum anuum) and Better Boy tomatoes (Solanum lycopersicum ‘Better Boy’) are examples of non-native plants that are currently not invasive. At present, these species don't pose a threat to native plants and have been cultivated by humans for centuries.
In other words, not all non-native species are invasive, but all invasive species are non-native. Non-native species are also sometimes termed “exotic species.”
The Canada thistle you see in Moraine Park may be a pretty purple flower, but it's a non-native weed invading and edging out the native plant species in the area, Rocky Mountain National Park / NPS file
What kind of harmful non-native species currently exist within Rocky Mountain National Park? Canada thistle and leafy spurge are fast-growing non-native plant species which can change the look of the landscape by overwhelming the park’s native grasses and plants. Not only that, but non-native plant species can be detrimental, even deadly, to the park’s wildlife. Common burdock, for example, has a sticky sap documented to fatally trap hummingbirds.
You can see more non-native plant species on the park’s Exotic Plant List page.
Non-native species are not just relegated to plants. Non-native animals invade habitats frequented by native animal species, edging them out while eating their food and infecting them with any diseases they may carry. For example, mountain goats were introduced into the state and made their way up to Rocky Mountain National Park, infecting the native bighorn sheep as well as eating their food and taking up space in sheep habitat. Because mountain goats are a significant threat to the survival of native bighorn sheep, the park has taken active measures to remove mountain goats entering the park. Park policy is to euthanize goats when feasible and safe to do so. There is no longer an option to relocate them to other areas of Colorado.
Regarding non-native plant species, the park created an Invasive Exotic Plant Management Plan. This 2018 combination management plan and environmental assessment details the issues and impacts invasive plants are wreaking on the park’s habitats and wildlife and the available alternatives available for eradicating these harmful plants.
