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

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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 hog damage in a corn field. (Courtesy Sam Wilson,  Nebraska Game and Parks Commission)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 map. Legend: Feral hog presence (brown); feral hog absence (yellow). (Courtesy James Merchant, Center for Advanced Land Management  Information Technologies, University of Nebraska-Lincoln)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 The mosquito is a carrier of West Nile Virus. (Courtesy USGS)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? West Nile Virus Dead Bird Surveillance, 2007. (Courtesy Karis Brown, Department of Health and Human Services)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 Common reed visible on sandbars along the river. (Courtesy Rich Walters, The Nature Conservancy)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? Common reed map. Legend: Phragmites (none reported), yellow; phragmites (some reported), orange; phragmites (significant infestation), brown. (Courtesy Howard Russell, Michigan State University)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. Emerald ash borer Emerald ash borer beetle.  (Courtesy Howard Russell, Michigan State University)The emerald ash borer, Agrilus planipennis, is a small, metallic green, highly destructive exotic beetle native to China and eastern Asia. It was discovered in southeastern Michigan near Detroit in the summer of 2002, and since then has been responsible for the death or decline of more than 15 million ash trees in the Detroit area. Since its discovery, emerald ash borer has killed more than 20 million ash trees in Michigan, Ohio and Indiana. The adult beetles nibble on ash foliage but cause little damage. However, the larvae (the immature stage) feed on the inner bark of ash trees, disrupting the tree’s ability to transport water and nutrients. Infestation is always considered fatal. There currently are no known predators of the ash borer in North America. What does this mean to Nebraskans? Damage caused by the emerald ash borer beetle. (Courtesy Troy Kimoto, Canadian Food Inspection Agency)Emerald ash borers probably arrived in the United States on solid-wood packing material carried in cargo ships or airplanes originating in their native Asia. The threat of the emerald ash borer has sparked a nationwide campaign to prevent transportation of infested wood materials, including firewood and pallets, into uninfested areas. Ash trees are well established in the communities and rural areas of Nebraska. Though emerald ash borer has not yet been found in Nebraska, the risk is high. Therefore, do not move firewood, do inspect your trees for signs of infestation, and spread awareness of the threat posed by the ash borer. Control efforts have cost municipalities, property owners, nursery operators and forest products industries tens of millions of dollars ( www.emeraldashborer.info). With early detection, damage can be prevented.

The strategy

These example invaders are only a cross section of invasive species threatening or potentially threatening Nebraska. We have witnessed the damage invasive species have caused in other countries and here in our own backyard. We have seen cane toads in Australia, zebra mussels in the Great Lakes region, non-native fire ants in the south, and European starlings on our porches. However, by taking a cue from what has happened elsewhere in the world, we can learn how to defend the homefront. Many Nebraskan’s have witnessed firsthand the loss of biodiversity and the damage that invasive species can cause to their property. Those who have not been directly affected have been indirectly affected by the impacts of invaders due to decreased yields in agricultural crops and other impacts on human food supplies, and threats to the natural resources and ecosystem functions we have come to depend upon. Mitigation can sometimes require the use of pesticides and herbicide applications that may have negative impacts on amphibian and invertebrate communities, water quality and human health. In some cases the economic or ecological costs of invasive species control can outweigh the benefits derived from control. Additionally, few control efforts work with one treatment application, and invasive species are often the first to colonize an area where other invasive species have been removed. Mitigation often requires increased use of pesticides, which may adversely affect beneficial organisms, water quality and human health. The cost of mitigation measures is a reason for concern. For example, USDA’s Animal and Plant Health Inspection Service increased its annual spending on emergency eradication programs more than twentyfold during the 1990s - from $10.4 million to $232 million. With ever increasing globalization and technological advances, humans are developing faster and more efficient ways to trade goods across ecological boundaries, further increasing the rate at which species are transported across geographic and geopolitical borders. What does this mean for Nebraskans? Taking the responsibility to survey for and report invasive species is a large first step. If you identify signs of any of the species listed above, or any species known to be a non-native invasive species in Nebraska, report it. Prevention and awareness will help keep native Nebraska ecosystems healthy, and save Nebraskans heavy costs down the road. Be sure to plant native plant species in your yard. Native species are beautiful and colorful, and contribute greatly to the success of native wildlife and invertebrates. More importantly, native species are adapted to the ecosystem and will take less time and money investments for property owners. Do not release or transport animals or plants. If you are a pet owner, return your animal to an animal rescue organization, like the Nebraska Humane Society. NEVER release an animal into the wild. Though it may feel like the right thing, these animals will either die, interbreed with closely related native species, or may otherwise harm native species and native habitat. Do not transport firewood or wood materials. Invertebrates traveling on these products may not be visibly detectable, but the damage they can cause is devastating. Inspect your terrestrial and aquatic vehicles before transporting them into Nebraska waters and roadways. Fish, invertebrates, seeds and vegetation can latch onto these vehicles and establish in native ecosystems, greatly impacting the native communities and potentially destroying sportfishing populations and recreational areas. Do not dump your bait. Though it may seem like an easy disposal method, releasing bait into a new ecosystem runs the risk of releasing invaders. Protect the population for every outdoor enthusiast, including you.

The alliance

Steps are being taken to prevent the spread of existing threats, and detect what species may pose a threat for the future. In Nebraska, one of these steps was the development of the Nebraska Invasive Species Project. This project is already building momentum toward an invasive species bio-security and management system in Nebraska. Agencies and organizations are working together to create a system that is integrated and relatively seamless across institutional boundaries. Our efforts are meant to develop a permanent system for data sharing and outreach concerning the management, spread and impacts of harmful invasive species in Nebraska. On Feb. 7, the Nebraska Cooperative Fish and Wildlife Research Unit (NECFWRU), with the support of The Nebraska Environmental Trust, kicked off the first Nebraska Invasive Species Conference. This event was planned with the input of the Nebraska Invasive Species Project partners: the Nebraska Game and Parks Commission, the National Park Service, The Nature Conservancy, the Nebraska Department of Agriculture, the Nebraska Weed Control Association, the Center for Advanced Land Management Information Technologies at the University of Nebraska-Lincoln, the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Services, and the USDA Natural Resources Conservation Service. The event attracted managers, conservationists and researchers from across the state of Nebraska. A series of speakers, representing a variety of agencies and organizations that are actively involved in invasive species management projects, presented their agency’s greatest challenges in invasive-species management. Both current and future perceived threats as viewed by different organizations were outlined, and discussions provided input into what future steps are needed in invasive species management in the state of Nebraska. This information is the beginning of the process to fill gaps in invasive-species research and overcome barriers in communication. During breakout sessions, smaller groups covered important issues in partnerships and collaborations, policies and legislation, threatened- and endangered-species issues, and developing recommendations for the future of invasive-species management in Nebraska. Recommendations from breakout sessions were similar. Recommendations included im­proving cooperation and information sharing; the need for formalized state-level coordination; developing legislative and policy proposals; establishing proactive conservation actions to reduce invasive species impact; creating prevention and early-detection systems - including risk assessment, prediction maps and monitoring networks; incorporating adaptive management into current management practices; and developing a focus on public education and outreach. Some of these recommendations are already in development, including the online resource and the formalization of state-level coor­dination. The Nebraska Inva­sive Species Project Coor­dinator, housed within the NECFWRU, has taken on the role to increase communications and maintain commitment and momentum for the future of invasive-species management in Nebraska. The online web portal can be found at snr.unl.edu/invasives. Through the work of these partners, and many more allies across the state, Nebraska is developing a coordinated front to defend Nebraska’s natural legacy for future generations.

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