Many invasive species look similar to the local plants and animals that belong in our backyards, deserts, forests and streams. Despite their ability to blend in, invasive species can be destructive to both native plants and animals, and humans.
They are often great adapters, and can outcompete important native species, disrupting ecosystems or causing native or rare species to decline. Conversely, native species help keep our ecosystems healthy and in balance.
Disclaimer: Invasive and non-native species are different concepts. A plant or animal can be non-native in an ecosystem, but not necessarily harmful or invasive. Yet, an invasive species is a non-native that always has a severe impact on the ecosystem it is “invading.”
Let’s compare a few invasive (and non-native) species that look highly similar to some of their local, native counterparts:
1. Medusahead vs bottlebrush squirreltail
Lookalike: Medusahead (Taeniatherum caput-medusae) — native to the Mediterranean Region, parts of Asia, Europe and North Africa.
Local resident: Bottlebrush squirreltail (Elymus elymoides) — native to most of North America west of the Mississippi River.
The first on our list of invasive lookalikes is an annual grass known as Medusahead. The plant gets its name from the seed head which has very large bristle-like appendages that look like the mythological figure, Medusa, who had snakes as hair. This invasive was first discovered in 1887 in the United States, arriving in a shipment of seeds. Medusahead is often mistaken for several native Great Basin grasses, including bottlebrush squirreltail and foxtail barley, which provide important forage for desert wildlife.
The problem: This species’ seeds grow more quickly than native seedlings, and ultimately outcompete native bunchgrasses. Medusahead also contains silica, which slows the decomposition of old plant parts, resulting in the formation of a thick, dense bed of thatch, which limits the germination of native plant species, reduces biodiversity and increases fuel for wildfires in the Great Basin.
2. Rainbow trout vs Lahontan cutthroat trout
Lookalike: Rainbow trout (Onchorhyncus mykiss) — native along the Pacific coast, from Alaska to northern Mexico.
Nevada State Fish and local resident: Lahontan cutthroat trout (Onchorhyncus clarkia henshawi) — native to the Lahontan Basin (northern Nevada and parts of California and Oregon) and listed as threatened under the Endangered Species Act.
Popular with anglers, the rainbow trout has a “rainbow” hue with a bright pink stripe running down its side. Rainbow trout can grow quite large and have been documented weighing up to 50 lbs. This fish is native to the Pacific Coast and associated waters, but now exists on almost every continent due to humans moving it around.
The somewhat similar Great Basin native is the Lahontan cutthroat trout, Nevada’s state fish. It has crimson red-orange marks on the throat (hence cutthroat) with black spots scattered over gray to olive green scales and can grow impressively large, weighing up to 40 lbs.
The problem: Although the rainbow trout is fun to catch, it is not native to the Eastern Sierra or Great Basin and it hybridizes with Lahontan cutthroat trout, reducing the genetic integrity and unique characteristics of this native fish. Along with loss of habitat, scientists have identified the introduction of non-native fish (like rainbow trout) as the top threat to the continued existence of Lahontan cutthroat trout.
3. Bullfrog vs Columbia spotted frog
Lookalike: Bullfrog (Lithobates catesbeianus) — native throughout the eastern United States from the Atlantic Coast to Oklahoma and Kansas.
Local resident: Columbia spotted frog (Rana luteiventris), Great Basin Distinct Population Segment — native to southeastern Oregon, southwestern Idaho, and northern and central Nevada.
Bullfrogs are only native to the eastern United States but can be found throughout the lower-48. Within the Great Basin, bullfrogs look similar to the Columbia spotted frog, which are olive green to brown with many black spots and can get to 3.5 inches long. In contrast, bullfrogs are olive brown with bright green upper lips and can get up to 6 inches long.
The problem: While the bullfrog is native to the eastern United States, it is invasive in the West. With few natural predators to keep populations in check, bullfrogs multiply quickly and outcompete native frogs, like the Columbia spotted frog. In addition, the population of Columbia spotted frog found in the Great Basin is considered at risk. Where these two species overlap, scientists have seen bullfrogs outcompeting and replacing the native frog.
4. Sierra Nevada red fox vs red fox
Lookalike: non-native red fox (Vulpes vulpes) — Any subspecies of red fox not native to the Sierra Nevada or Cascades mountain ranges of California and Oregon.
Local resident: Sierra Nevada red fox (Vulpes vulpes necator) — Found in the southern Cascades Range of Oregon and California and the Sierra Nevada of California.
At first glance, Sierra Nevada red fox may look like a non-native red fox, but it is smaller than your average fox and has denser fur…even its footpads are fur-covered during the winter. These adaptations help it survive in its cold, high-elevation range.
The problem: The non-native red fox and the Sierra Nevada red fox are genetically different which means that they evolved over time to be distinct. Currently, scientists are concerned about them interbreeding. Too much interbreeding could affect the genetic makeup of Sierra Nevada red fox, reducing its distinctness. On the other hand, some interbreeding with non-native red foxes has already occurred in the Sierra Nevada, and the result so far appears to have been beneficial. The Sierra Nevada red fox population is so small that it is has been suffering from inbreeding; therefore, interbreeding with a few non-natives is helping to provide genetic variation for the population, resulting in an increase in reproductive success in recent years. The solution for Sierra Nevada red fox may actually be about finding the right amount of interbreeding with non-natives, rather than preventing it completely.
The issue of invasive species may be complex. Some invasives are particularly similar to native species. Other invasives are even native to a portion of the United States. A select few non-natives might even be beneficial and can help prevent inbreeding (red fox), but generally, these invaders are suspect, especially when they blend in and appear to belong to the Eastern Sierra of California and the Great Basin in Nevada.
Support your native plants and animals by taking an interest in and caring for our environment! Here are some ways to get started with invasive weeds like medusahead (there are many more plant invaders, including things like cheatgrass and yellow star-thistle):
- Report invasive weeds to the local land manager or to your state agriculture department.
- Clean off your shoes before traveling to a new location to avoid carrying the seeds on the bottom of your shoes, where they can spread in pristine areas.
- If you remove plants that have seeds, please take care to not help this plant by not spreading the seeds around.
Knowledge is power. Share information with friends and families, who can also keep a look out for invasive weeds.
By Michelle Hunt/Reno FWO and Joanna Gilkeson/Reno FWO