Invasive species in Nebraska: The battle for Nebraska’s natural legacy

By Annabel Major and Craig Allen

The situation

You may have heard them called alien, exotic, feral or non-native, but they all point to the same suspect: invasive species. For decades, humans have waged war upon a common enemy. Arriving in many different forms, often little is known about these elusive invaders until they make themselves apparent by choking out native flora and fauna, irreversibly damaging ecosystems and costing Nebraskans millions of dollars in control efforts. With examples such as the “snakezilla” (northern snakehead fish) and the “green menace” (emerald ash borer beetle) in the eastern United States receiving media attention, it is time we turn our attention to Nebraska.

Biological invasions are a growing threat to both human enterprise and ecological systems. The rate of introductions continues to increase, and many countries are developing organized plans to strengthen bio-security in the face of these threats. The negative impacts of biological invasions are economically and ecologically significant, and while they remain incompletely quantified, they are clearly substantial. In 2000, David Pimental of Cornell University, and colleagues, estimated that the economic costs of invasive species for the United States, the United Kingdom, Australia, South Africa, India and Brazil exceeded $314 billion per year. David Pimental and colleagues made conservative estimates of costs associated with invasive species in the United States, which exceeded $120 billion per year in 2005. Ecological and environmental costs are considerably more difficult to quantify, but include the extinction of native biota, disruption of community structure and changes in ecological processes, with associated losses of ecosystem services and capital. Some of these ecosystem services we may not yet have identified, such as human health and medical applications or fuel innovations.

Invasive non-native species negatively impact a number of vertebrate and invertebrate species, and by direct or indirect means may change ecological process, structure and function. For more than half of the vertebrate species recently extinct, invasive non-native species are a major cause of decline, second only to habitat loss. In the United States, it is estimated that invasive non-native species negatively affect more than 40 percent of threatened and endangered species. In Nebraska, the Legacy Blueprint identifies invasive non-native species as the second most important threat to at-risk native species and communities. Loss of native species is a major threat to the biodiversity, and overall health, of ecosystems. Therefore, it is important to identify and target detrimental species before they are firmly established. But how do Nebraskans find an enemy who has not yet struck or whose damage may yet to be identified?

Some primary targets

Feral hogs

Feral hogs, which include Eurasian wild boars native to Europe and Asia and domestic pigs that have escaped captivity, are quickly becoming a threat to Nebraska agriculture and ecosystems. Feral hogs cause significant property destruction to both rural and urban landowners. Feral hogs are omnivorous and root through crop and pasture land, as well as lawns and gardens, in search of food. This process not only destroys property but can irreversibly damage forest systems, ponds and wildlife, including turkey and rare bird species.

What does this mean to Nebraskans?

Feral hogs have already become established in over half of the states in the U.S. Wildlife agencies and landowners fight vigorously to prevent the economic and ecological damage caused by these invaders. Their high reproductive rate and adaptability make them difficult to control. And now they have entered Nebraska. For Nebraska, prevention is the only effective and cost-effective method. If you suspect evidence of feral hogs on your property, or for more information, please contact the Nebraska Game and Parks Commission at 402-471-0641. With your help, Nebraska Game and Parks Commission can work with Nebraskans to keep the threat of feral hogs under control.

West Nile Virus

West Nile Virus is a virus carried by infected birds and passed to animals, including equine species and people, via a mosquito vector. Mild cases of West Nile infection can cause a slight fever and/or headache. Severe infections are marked by a rapid onset of a high fever, head and body aches, and usually occur five to 15 days after exposure. There is no specific treatment of viral infections, other than to treat the symptoms and provide supportive care. Those who are at highest risk of becoming seriously ill from West Nile infection are persons over the age of 50. Healthy children and adults are at very low risk for infection.

What does this mean to Nebraskans?

The cost attributed to death or euthanasia of equine West Nile Virus cases in Colorado and Nebraska for 2002 is estimated to be $600,660 (USDA-APHIS). Although the chances of a person becoming ill are small, there are some simple steps you can take to reduce your risk even further. To prevent exposure and potential infection, it is recommended that people reduce the number of mosquitoes in their yards, neighborhood and community. Find out more at www.dhhs.ne.gov/puh/epi/wnv/.

Common reed

The common reed, Phragmites australis, has greatly impacted river systems, choking water flow and increasing flood risk. Listed as one of many of the Nebraska Department of Agriculture’s Watch List species, the common reed has received a lot of attention in Nebraska. This plant can be found throughout the Great Plains, forming dense patches in wet, fertile soils along ponds, lakes, marshes and waterways, including the Platte River ecosystem. This species can spread through seeds and rhizomes, making it very difficult and costly to control.

What does this mean to Nebraskans?

The common reed has quickly spread throughout river ecosystems, and continues to grow. These areas, once sandbars and habitat for protected species such as terns and plovers, become dense monocultures. These monocultures hold little to no value for native wildlife and plants, and slow water flow in the infested areas. Slowed water flow leads to increased risk of flooding, which could cost landowners millions in damages. Prevention and eradication are the only effective means of controlling this species. However, once it is established, it is very difficult to control. Research is in progress on what methods, such as grazing and disking, are cost-effective control measures. For more information about the Noxious Weeds and Watch List species, visit the Nebraska Invasive Species Web site at snr.unl.edu/invasives.

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