Copyright (c) 2008 University of Nebraska - Lincoln All rights reserved. http://digitalcommons.unl.edu/nwrcinvasive Recent documents in Managing Vertebrate Invasive Species en-us Wed, 25 Jun 2008 07:06:52 PDT 3600 http://digitalcommons.unl.edu/nwrcinvasive/56 http://digitalcommons.unl.edu/nwrcinvasive/56 Mon, 23 Jun 2008 09:11:48 PDT At least 161 introduced/invasive vertebrates have become established in the United States and its territories, including at least 81 mammalian, 94 avian, and 86 reptilian/amphibian species. Particularly problematic species include feral cats and dogs; feral pigs; commensal rats and mice; starlings, pigeons, and house sparrows; and bullfrogs, brown treesnakes, and coqui frogs. We briefly review these introductions and the types of damage they cause. We review the basic types of methods used for control or eradication of each taxonomic group, including physical, chemical, biological, and cultural methods. We also discuss some of the challenges in managing these species, including issues with the use of toxicants, land access, public attitudes, and monitoring difficulties. Finally, we discuss some ongoing research and future research needs, including fertility control, improved detection methods, improved attractants, improved barriers, improved capture methods, and risk assessment methods. Gary W. Witmer http://digitalcommons.unl.edu/nwrcinvasive/55 http://digitalcommons.unl.edu/nwrcinvasive/55 Mon, 23 Jun 2008 09:09:09 PDT The multiple economic, environmental, and animal and human health impacts of invasive species pose complex challenges in policy formation and governmental coordination. The National Invasive Species Council (NISC) was established by an Executive Order in 1999 to provide coordination, planning and facilitate cooperation among the diverse federal agencies and to take a more comprehensive approach to invasive species. NISC, assisted by the nonfederal Invasive Species Advisory Committee (ISAC) has developed several tools and enhanced capacities to address invasive species. Additionally, NISC has helped place greater emphasis on essential prevention, early detection and rapid response, research, public outreach, and international cooperation efforts. Invasive vertebrates are an increasing concern for NISC and for state, tribal, and local governments and the private sector. The invasive vertebrates further complicate an already complex issue. Invasive vertebrates require an even greater level of coordination and understanding. Important questions such as, best practices for the humane control and removal and effective public outreach messages must be answered. NISC continues to emphasize the critical need for effective multi-sector coordination when addressing invasive vertebrates. Lori Williams http://digitalcommons.unl.edu/nwrcinvasive/54 http://digitalcommons.unl.edu/nwrcinvasive/54 Mon, 23 Jun 2008 09:01:05 PDT Brushtail possums are a major invasive pest in New Zealand. A decision support system (DSS) has been developed to enable those involved in operational planning or delivery of possum control to access available relevant knowledge when making operational decisions. The DSS comprises checklists that ensure users consider relevant constraints and issues, a database of best-practice information on possum control, and an "expert" system that recommends actions based on information provided by the user. Bruce Warburton http://digitalcommons.unl.edu/nwrcinvasive/53 http://digitalcommons.unl.edu/nwrcinvasive/53 Mon, 23 Jun 2008 08:56:17 PDT Acknowledgments: Many people worked behind the scenes to make the symposium a success. The organizing committee would like especially thank Sue Brungardt, Patrick W. Burke, Marilyn J. Howell, Susan M. Jojola, Nicole N. Lorimer, Michael E. Pierce, John D. Eisemann, Jeanette R. O'Hare, Barbara L. Messineo, and Laurie A. Paulik for their help at the symposium. We also thank Colorado State University's Conference Services for assisting with registration and other logistics of the symposium. We thank the staff of the Hilton Hotel, Fort Collins, for providing all the on-site needs of the symposium. We also thank Hilda Diaz-Soltero, USDA Liason to the National Invasive Species Council, for providing support for the publication of the proceedings. Finally, we thank National Wildlife Research Center Director, Dr. Richard L. Bruggers, for his encouragement and support in organizing and hosting the symposium. Gary W. Witmer Editor http://digitalcommons.unl.edu/nwrcinvasive/52 http://digitalcommons.unl.edu/nwrcinvasive/52 Mon, 23 Jun 2008 08:51:25 PDT Conventional methods for the control of invasive pests are generally effective only on small-space scales or short-time frames. For most well established pest populations, longer-term efforts to manage the problem have been largely abandoned. I examine the potential of using "autocidal" genetic techniques to control terrestrial vertebrate pests, based on the inheritance through males of transgenes that either sterilize females or convert them into functional males ("daughterless"). Simulation analysis of two high profile pest species, the cane toad (Bufo marinus) in Australia and brown rats (Rattus norvegicus) in an urban environment, using realistic parameters, suggests that virtual eradication could be achieved at apparently realistic stocking rates within 100 years for toads, and in less than 20 years for rats. The essential genetic requirements for autocidal technology (the ability to genetically transform the pest, genes that when blocked cause sex-specific infertility or sex change, and a means of shutting off the construct for breeding purposes) have already been demonstrated in rodents and are likely to be available in other pests, based on broad conservatism of genetic mechanisms of sex differentiation in vertebrates. Hence, there appear to be no major logistical or technical impediments to developing a genetic control program against many pest species. However, the models also indicate that a recombinant pest control program would be difficult against species whose populations are under strong density dependent regulation or are so large that absolutely high numbers of carriers need to be stocked to achieve control. More potent genetic options than those modelled could be feasible, but their use needs to be tested against public acceptability, due to the apparently higher risk they pose for non-target populations and species. Ronald E. Thresher http://digitalcommons.unl.edu/nwrcinvasive/51 http://digitalcommons.unl.edu/nwrcinvasive/51 Mon, 23 Jun 2008 08:45:33 PDT The internet is often an unregulated pathway that can lead to the introduction of invasive species. Surveillance of internet-related sale or trade activities can reduce the movement of potentially invasive species and serve to lessen the risk of an introduction. The Invasive Species Internet Monitoring System automates the process of searching the internet for suspect sites (e.g., internet storefronts, chat rooms, etc.) involved in the sale or trade of targeted species. Additionally, this software system incorporates data management features that permit the archiving of suspect website content, assists subject matter experts in evaluating sites for risk, send informational emails to website owners and can track sites for compliance. This software system is currently being used by United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine and the Smuggling, Interdiction and Trade Compliance Program to search for websites selling regulated insects, weeds, mollusks, fruits and vegetables, and for animals and animal products that have the potential to carry Highly Pathogenic Avian Influenza. Karl Suiter http://digitalcommons.unl.edu/nwrcinvasive/50 http://digitalcommons.unl.edu/nwrcinvasive/50 Mon, 23 Jun 2008 08:43:42 PDT In the 1940s the brown treesnake (Boiga irregularis) was accidentally transported to Guam and became established. Brown treesnakes have caused and continue to cause major problems for the ecology, economy, and quality of life on Guam. As Guam's snake densities increased in the late 1970s, extralimital encounters began to be reported on islands with transportation links to Guam. In 1993, a major effort was initiated to reduce the potential for brown treesnakes to accidentally enter Guam's transportation system. In 2002, a multi-agency Rapid Response Team (RRT) was established to assist in detection and capture of brown treesnakes on recipient islands after being accidentally transported from Guam. Since its creation, the RRT has conducted 2-5 training courses annually on Guam and 16 off-Guam field operations. As of 2006, the RRT consisted of 66 members located throughout the Pacific region and the United States mainland. The RRT has incorporated research results from affiliated agencies, such as means to improve snake detectability at low densities, effectiveness of control tools in rodent-rich environments, and predicting movements of snakes accidentally translocated. The RRT continues to work with regional island groups, improving communication networks, elevating public awareness, and developing response capabilities. James W. Stanford http://digitalcommons.unl.edu/nwrcinvasive/49 http://digitalcommons.unl.edu/nwrcinvasive/49 Mon, 23 Jun 2008 08:40:19 PDT Invasive pest eradication is an increasingly viable management option for conservation and wildlife managers all over the world. The list of successful rodent eradications from isolated islands continues to grow globally. Now, with the development of effective pest exclusion technologies, the opportunities for eradicating multiple species of vertebrate pests from progressively larger fragments of habitat in mainland situations are also increasing. Attempts at eradicating up to fifteen separate species of pest mammal from indigenous forest fragments protected by Xcluder pest proof fencing have been made on the main islands of New Zealand. These include various assemblages of multiple species of deer (Cervidae), feral pig (Sus scrofa), brushtail possum (Trichosurus vulpecula), lagomorphs, rodents and a range of other predators. At some sites, individual species remain, while at others, complete eradication of a full suite of previously present pest species has been achieved. Using the 3,400 ha Maungatautari Project as a case study, we explore critical issues associated with successful pest eradication and reinvasion management in habitats protected by pest proof fencing, including eradication methods, finding and removing survivors, monitoring and surveillance, and the behavior of reinvading pests. The transfer of the techniques successfully developed in New Zealand to other parts of the world is likely to depend as much on the regulatory environment at the management site as on the pest species present. Cam Speedy http://digitalcommons.unl.edu/nwrcinvasive/48 http://digitalcommons.unl.edu/nwrcinvasive/48 Mon, 23 Jun 2008 08:32:23 PDT ī The coqui frog (Eleutherodactylus coqui) is native to Puerto Rico and was accidentally introduced to the State of Hawai'i through contaminated nursery products from the Caribbean. Since its introduction in the late 1980s, coqui have become widely dispersed and in some areas population densities have reached 55,000 frogs/ha. The coqui frog is a species of concern because individual frogs can produce sound levels of 80 decibels (at 0.5 m), which has caused sleep loss to residents and affected the quality of life in Hawai'i. Economic concerns in infested areas include diminished property values and sales, impacts on tourism, and decreased sales in the floriculture and nursery industry. In addition, research indicates that the coqui has potential ecological effects as they might predate on endangered invertebrates and shift nutrient cycling processes in native forests. Control efforts have focused on habitat modification and applying chemical solutions of either 16% citric acid or 3% hydrated lime. Hot water or vapor treatments of plants are also effective control methods. Eradication of the coqui frog is not considered attainable on the Island of Hawai'i and seems unlikely for Maui, but may be possible on the islands of Kaua'i and O'ahu. Hans Sin http://digitalcommons.unl.edu/nwrcinvasive/47 http://digitalcommons.unl.edu/nwrcinvasive/47 Mon, 23 Jun 2008 08:28:38 PDT An account of global initiatives in invasive alien species, including vertebrates, was presented based on the author's experience and that of colleagues, mainly in the developing world. The account focused on those programs which highlight typical problems or best practice for design and which promised improvements in the future. Some of the characteristics of these programs were described and discussed. Techniques used in vertebrate control programs, especially in developing island states, were also described with a commentary on their efficacy and suitability for use. Finally, some future directions were recommended in terms of the design of in-country and regional programs and the methodology best suited for these programs. Greg Sherley http://digitalcommons.unl.edu/nwrcinvasive/46 http://digitalcommons.unl.edu/nwrcinvasive/46 Fri, 20 Jun 2008 11:06:31 PDT Polyvinyl chloride (PVC) tubes are effective bait stations for delivering dead neonatal mice (DNM) treated with the oral toxicant, 80 mg acetaminophen, to brown treesnakes (Boiga irregularis) in accessible jungle forest on Guam. However, PVC tubes are not practical for delivery of baits to remote areas of jungle or the forest canopy. Further, it is important that baits entangle in the canopy and not fall to the ground where they can be scavenged by non-target animals such as crabs. Data from helicopter aerial deployment of untreated DNM with radio transmitters that landed on the ground in areas of high coconut crab (Birgus latro) and hermit crab (Coenobita spp.) abundance showed that 67% of DNM were taken by crabs and 11% by monitor lizards (Varanus indicus). In contrast, in low crab abundance areas crabs took 24% of the DNM that landed on the ground. It is evident from these data that a flotation system that delivers DNM to the canopy is needed; otherwise non-target animals will remove DNM, making them unavailable for snakes. Seven aerial flotation devices were evaluated. Promising aerial devices are two types of commercial cardboard paper streamers that resulted in 75% - 85% of the DNM becoming entangled in the canopy. Peter J. Savarie http://digitalcommons.unl.edu/nwrcinvasive/45 http://digitalcommons.unl.edu/nwrcinvasive/45 Fri, 20 Jun 2008 11:00:35 PDT Conservation is essentially a social activity - it is about, by and for people. Managing invasive species on islands to reduce their "community effects" (that is, effects on communities of people as well as on communities of plants and animals) makes good sense. Consequently, many demonstration projects supported as part of the Pacific Invasives Initiative involve social and economic objectives as well as biological ones. In New Caledonia, for example, dialogue between conservation agencies and local tribes about a proposed pest mammal control project on Mont Panié has been taking place for nearly 10 years. As well as being involved in pest control activities to achieve biodiversity conservation outcomes, there is particularly strong local support for a proposed project to reduce feral pig (Sus scrofa) impacts in tribal gardens. It is anticipated that reduced pig impacts will lead to important improvements in peoples' livelihoods. A proposal to eradicate invasive cane toads (Bufo marinus) from Viwa Island in Fiji to protect an endangered ground frog was modified following consultation with local residents to first include the eradication of feral cats (Felis catus), feral dogs (Canis familiaris), and rats (Rattus spp.). These preliminary eradications were undertaken by the residents, with training and support from eradication specialists. Viwa islanders now have the knowledge and skills to ensure their island remains free of these pests. Also, Fiji Vatu-I-Ra Island is an important seabird breeding site. Local residents gave their support for rats to be eradicated from the island. Several people were trained and participated in the eradication operation. In addition to removing predation pressure on nesting seabirds and creating opportunities for an eco-tourism business, another early outcome has been increased measures by the owners to protect the island from further human-induced impacts. These and other demonstration projects are discussed to illustrate attempts at achieving biological, social and economic objectives through managing invasive species on islands. Alan Saunders http://digitalcommons.unl.edu/nwrcinvasive/44 http://digitalcommons.unl.edu/nwrcinvasive/44 Fri, 20 Jun 2008 09:53:01 PDT The red fox (Vulpes vulpes) has wreaked havoc on mainland Australia's environment and agricultural production since its introduction in the 1870s. Over the same period, the southern Australian island State of Tasmania has remained virtually fox-free, allowing its unique biodiversity to remain relatively pristine. Recently, an unknown number of foxes were deliberately or accidentally introduced to Tasmania. Some of those animals and possibly their progeny now live in the wild in Tasmania. Finding foxes in a state the size of Tasmania presents special problems for wildlife managers, but is essential to prevent their establishment in this stronghold for Australian marsupials. To assist in finding foxes in Tasmania, we have developed DNA detection approaches specifically for foxes that utilize the ubiquitous mitochondrial DNA found on the surface of mammal scats. Using these approaches, fox DNA has been detected in three different regions in Tasmania and have provided the basis for intense control efforts in those areas. We are now expanding our approach to include other predatory mammals of interest (including both native marsupials and other introduced mammals) and increasing the breadth and scope of our surveys. Stephen D. Sarre http://digitalcommons.unl.edu/nwrcinvasive/43 http://digitalcommons.unl.edu/nwrcinvasive/43 Fri, 20 Jun 2008 09:50:02 PDT Invasive rats continue to colonize rat-free islands around the world. To prevent rats from establishing on rat-free islands, especially following their eradication, biosecurity actions are required to enable early detection and elimination. Rats arrive at islands by both human transportation and by swimming. There are very little data on the rates of rat transportation by humans, although it is known that they are not negligible. There are better data on the distances rats can swim, allowing estimates to be made of the risk of reinvasion of islands close to source populations. Biosecurity prioritization must take place across all rat-free islands, balancing the likelihood and impact of rat establishment. Dense grids of poison bait stations are not preferable for preventing rat invasion. Instead, surveillance systems that integrate multiple device types appear to be best for intercepting invading rats, but must be tested to ensure they are effective. This can be done by releasing a controlled number of monitored rats onto a rat-free island. Islands can now be maintained rat-free despite non-negligible reinvasion rates; however, in some cases islands must be managed within a larger meta-population context and eradication may never be achieved. James C. Russell http://digitalcommons.unl.edu/nwrcinvasive/42 http://digitalcommons.unl.edu/nwrcinvasive/42 Fri, 20 Jun 2008 09:48:04 PDT Parrots have been transported around the world since the 1400s and about 44 species have established populations outside of their native ranges. At least 70% of these introduced species were identified as potential agricultural pests, compared to only 15% of all parrot species. At least 74 exotic psittacines have been reported in the wild in the United States, but only nine species were considered established. Since 1990, 24 psittacine species have been sighted in the wild in Hawai`i, about 21 species regularly occur on the main islands and at least five appear established. Past history of successful introduction, recent status of introduced populations, and life history traits were used to identify parrots which, if introduced, appeared most likely to establish nonindigenous populations. Potential impacts related to ecology, agriculture, and health were diverse but poorly documented in the literature. Five species were the most widespread and abundant species, and were considered established. Four more species with rapidly expanding ranges and increasing populations may become naturalized. Nine species had significantly expanded ranges and increased populations. Several introduced populations remained low for 10-15 years before rapidly increasing and becoming established; similar lag periods for other psittacines have approached 30 years. Douglas E. Runde http://digitalcommons.unl.edu/nwrcinvasive/41 http://digitalcommons.unl.edu/nwrcinvasive/41 Fri, 20 Jun 2008 09:46:06 PDT Climate matching identifies extralimital destinations that could be colonized by a potential invasive species on the basis of similarity to climates found in the species' native range. Climate is a proxy for the factors that determine whether a population will reproduce enough to offset mortality. Previous climate matching models (e.g., Genetic Algorithm for Rule-set Prediction [GARP]) for brown treesnakes (Boiga irregularis) were unsatisfactory, perhaps because the models failed to allow different combinations of climate attributes to influence a species' range limits in different parts of the range. Therefore, we explored the climate space described by bivariate parameters of native range temperature and rainfall, allowing up to two months of aestivation in the warmer portions of the range, or four months of hibernation in temperate climes. We found colonization area to be minimally sensitive to assumptions regarding hibernation temperature thresholds. Although brown treesnakes appear to be limited by dry weather in the interior of Australia, aridity rarely limits potential distribution in most of the world. Potential colonization area in North America is limited primarily by cold. Climatically suitable portions of the United States (US) mainland include the Central Valley of California, mesic patches in the Southwest, and the southeastern coastal plain from Texas to Virginia. Gordon H. Rodda http://digitalcommons.unl.edu/nwrcinvasive/40 http://digitalcommons.unl.edu/nwrcinvasive/40 Fri, 20 Jun 2008 09:41:27 PDT Many people would not consider their family complete without a pet. Unfortunately, for some pet owners, circumstances arise that prevent them from being able to properly care for their companions and pet abandonment has become one of the most common pathways of vertebrate species introduction. It is also one of the most challenging pathways to address once the animals become established, eradication and control programs face significant public scrutiny and are often challenged by "animal rights" groups. Prevention measures are thus the key to minimizing the size and impacts of the "pet release pathway." Habitattitude is a proactive campaign designed and implemented by the Pet Industry Joint Advisory Council and partners to prevent the introduction of unwanted pets into natural systems. The campaign has three components: (1) educating consumers to make wise pet choices, (2) providing resources to enable high standards in animal care and maintenance, and (3) encouraging pet owners to choose among several alternatives to the release of their pets if problems do arise. Habitattitude messages are being promoted in pet stores, product advertisements, industry trade shows, and industry-relevant magazines. Jamie K. Reaser http://digitalcommons.unl.edu/nwrcinvasive/39 http://digitalcommons.unl.edu/nwrcinvasive/39 Fri, 20 Jun 2008 09:38:48 PDT Island ecosystems are highly sensitive to the impacts of introduced species. Non-native invasive snakes, lizards, and amphibians can introduce diseases into native populations and have other deleterious effects through predation, competition, and habitat manipulation. The United States (US) Virgin Islands are situated on the Puerto Rican Shelf in the Caribbean Sea and have a long history of human impacts and species introductions. Two species, the green iguana (Iguana iguana) and the red-legged tortoise (Geochelone carbonaria) were historically introduced and have become naturalized with little apparent impact to the local ecosystem. Recent years, however, have seen the introduction of several highly invasive species that have proved to have severe impacts when introduced elsewhere, specifically the Cuban treefrog (Osteopilus septentrionalis), cane toad (Bufo marinus), and the red-eared slider (Trachemys scripta). The distribution of non-native herpetofauna has been documented on all main islands of the US Virgin Islands and potential routes for introduction and dispersal have been identified. Additional species are still being identified, having arrived via cargo shipments from other Caribbean ports. Renata J. Platenberg http://digitalcommons.unl.edu/nwrcinvasive/38 http://digitalcommons.unl.edu/nwrcinvasive/38 Fri, 20 Jun 2008 09:35:11 PDT The more than 50,000 species of plants, animals, and microbes introduced into the United States (US) cause more extinction of native species than most any other threat and cause more than $120 billion in damages and control costs each year. In particular, invasive mammals and birds cause major environmental and economic losses totaling about $46 billion per year in damage and control costs per year. Feral cats, rats, and hogs are especially serious pests. Pigeons and starlings are a major concern in cities and US agriculture. Prevention and management strategies will be discussed. David Pimental http://digitalcommons.unl.edu/nwrcinvasive/37 http://digitalcommons.unl.edu/nwrcinvasive/37 Fri, 20 Jun 2008 09:32:06 PDT The brown treesnake (BTS) has been on Guam for about 50 years and in this period has caused extensive ecological, economic, and social damage. It has also repeatedly dispersed from Guam via the transportation network, arriving at numerous locations. However, the conditions snakes face in surface shipping are unknown, making assessment of the risk of snake survival impossible. To address this, we recorded thermal conditions in surface shipments leaving Guam and identified factors that determine these conditions. We monitored 16 shipments to locations in Micronesia and the United States mainland and conducted a series of intensive studies at the Naval dock facility, using up to 29 containers at a time. Maximum temperatures recorded while containers were in transit were likely too low to consistently kill snakes. Empty exhibited uniformly high temperatures, but filled containers did not heat as much, nor as evenly. Maximum temperatures inside boxes and furniture are even lower, though often still exceed 40o C. Exposed containers reached high temperatures, but shading by other containers greatly decreased the maximum temperature reached inside. Gad Perry http://digitalcommons.unl.edu/nwrcinvasive/36 http://digitalcommons.unl.edu/nwrcinvasive/36 Fri, 20 Jun 2008 09:24:59 PDT The impact of invasive species on native biodiversity is increasing worldwide. Mammalian invaders are formidable ecological and economic threats, and tree squirrels are models of such challenges. We review the worldwide distribution of tree squirrel introductions and detail their nearly universal success. The biological characteristics of tree squirrels that enable success as invasive species are: high reproductive potential, high vagility, diverse food habits, ability to construct nests, and plasticity in human-impacted landscapes. We document costs and benefits of tree squirrel introductions, and discuss existing management strategies planned for some species. We focus on an introduced population of Mexican red-bellied squirrels (Sciurus aureogaster) found in Biscayne National Park, Florida, United States. Originally introduced to Elliot Key in 1938, the population expanded until Hurricane Andrew in 1992. Thought to be extirpated, recent sightings initiated a project to assess status and distribution within the Park. A field study has provided valuable information on potential and realized impacts that the squirrel population has on the native ecosystem that includes several species of conservation concern. Management strategies for Mexican red-bellied squirrels can be formed after research to develop prudent and effective means to meet the challenges that result from control measures to deal with this exotic species. Geoffrey H. Palmer http://digitalcommons.unl.edu/nwrcinvasive/35 http://digitalcommons.unl.edu/nwrcinvasive/35 Fri, 20 Jun 2008 09:16:43 PDT Control of invasive vertebrate pests is likely to be needed in perpetuity unless their pest status changes or they are completely eradicated, both of which seem unlikely at present. This emphasizes the need for pest managers to adopt long-term strategies that are both ecologically sound and cost-effective. We suggest that a strategy for simultaneous management of multiple sympatric species of pests is preferable to a single-species approach. While present strategy involves periodic control over entire areas to achieve management aims, modelling suggests that a strategy of localised elimination followed by perimeter control offers significant cost-savings in the long term. We are therefore researching three aspects of this strategy: (1) the further refinement of aerial baiting by identifying principal causes of individual pest survival, (2 the optimal deployment of control devices around the perimeter following localised elimination, and (3) the development of an efficient pest detection device to enable targeted elimination of survivors. Graham Nugent http://digitalcommons.unl.edu/nwrcinvasive/34 http://digitalcommons.unl.edu/nwrcinvasive/34 Fri, 20 Jun 2008 09:14:11 PDT http://digitalcommons.unl.edu/nwrcinvasive/33 http://digitalcommons.unl.edu/nwrcinvasive/33 Fri, 20 Jun 2008 09:08:31 PDT The endemic fauna of New Zealand evolved in the absence of mammalian predators and their introduction has been responsible for many extinctions and declines. Predator control will have to be on-going if some native species are to survive on the mainland. Currently, predator control relies largely on labourintensive trapping, so the development of humane predator-specific toxins would provide valuable additional control methods. Para-aminopropiophenone (PAPP) is being investigated as a toxin for feral cats (Felis catus), stoats (Mustela erminea), and wild dogs (Canis familiaris). Carnivores appear to be much more susceptible to PAPP than birds, so it potentially has a high target specificity, at least in the New Zealand context. Pen trials with 20 feral cats, 15 stoats, and 14 dogs have been undertaken using meat baits containing a proprietary formulation of PAPP. A PAPP dose of 20-34 mg/kg was lethal for feral cats, 37-95 mg/kg was lethal for stoats, and 26-43 mg/kg was lethal for dogs. Our results suggest that PAPP is a humane and effective toxin for control of feral cats and stoats, and possibly for wild dogs. We are now continuing studies towards product registration, which will include the assessment of non-target effects, particularly on birds. Elain C. Murphy http://digitalcommons.unl.edu/nwrcinvasive/32 http://digitalcommons.unl.edu/nwrcinvasive/32 Fri, 20 Jun 2008 09:05:44 PDT Texas Wildlife Services (WS) personnel conduct feral hog damage management projects to protect a variety of resources in Texas. For the past 12 years, WS personnel have conducted feral hog (Sus scrofa) damage management projects on an 11,000 acre wildlife management area (WMA) and surrounding farmlands located in central Texas. The WMA is managed by the United States (US) Army Corp of Engineers and Texas Parks and Wildlife Department. Surrounding areas are farmlands and the primary crops grown there are corn and grain sorghum. Feral hogs have damaged area grain crops and the US Army Corp of Engineers property. Annual projects have been conducted to reduce feral hog damage to crops and property. WS personnel have used an assortment of methods and strategies in a management plan to reduce feral hog damage in the area. This paper is a review of those methods, strategies, and the plan. T. J. Muir http://digitalcommons.unl.edu/nwrcinvasive/31 http://digitalcommons.unl.edu/nwrcinvasive/31 Fri, 20 Jun 2008 09:03:56 PDT Effective conservation of native biodiversity on islands often requires the eradication of destructive non-native vertebrates. There are risks in conducting an eradication project, however, including the risk that the effort will fail to remove all the individuals, and the risk that the removal of the species will trigger ecological cascades with unanticipated and undesired consequences. Managers must plan to reduce such risks, and also maximize the return on investment of the limited conservation resources available for restoration programs. I discuss four vertebrate removal projects implemented on Santa Cruz Island, CA, over the past 25 years: sheep, golden eagles, pigs, and wild turkey. Collectively, these projects illustrate general principles for reducing risks inherent in eradication projects and for enhancing efficiencies in delivering conservation outcomes. Lessons from this case study - such as the value of disciplined engagement of the target population, strategic sequencing of restoration projects, and intensification of effort through the application of advanced technologies - can be applied to help accelerate the restoration of island ecosystems elsewhere and so the conservation of highly imperiled island biota. Scott A. Morrison http://digitalcommons.unl.edu/nwrcinvasive/30 http://digitalcommons.unl.edu/nwrcinvasive/30 Fri, 20 Jun 2008 09:01:23 PDT There is an increasing number of calls for action on a wide range of invasive non-native species, but only a limited resource to deal with them. It is clearly important for policy makers and others to be able to prioritize where these scarce resources are directed in order to maximize their conservation benefit. Coordination of effort, and knowledge sharing are clearly important as are risk assessment methods which attempt to quantify the risk posed by a range of species that are either present or are likely to invade. Great Britain, as an island, has advantages over continental landmasses in that prevention of invasion by terrestrial and freshwater species is more straightforward. However, there is still a large number of detrimental nonnative species present in the country and this is likely to increase. This paper describes the recent establishment of a mechanism to coordinate action against non-native species in Britain. It also details the development of a risk analysis process which will provide scientifically robust advice to the government and allow policy makers and others to base prioritize actions against invasive species on a more sound footing. Niall Moore http://digitalcommons.unl.edu/nwrcinvasive/29 http://digitalcommons.unl.edu/nwrcinvasive/29 Fri, 20 Jun 2008 08:59:56 PDT The USDA's National Wildlife Research Center (NWRC) has successfully researched and developed a number of chemical and immunologically-based wildlife contraceptives. Diazacon interferes with cholesterol metabolism and disrupts steroidogenesis, while nicarbazin (registered as OvoControl-P® and OvoControl-G®) disrupts the structure of the vitelline membrane of bird eggs. Immunologically-based agents act to stimulate targeted antibody production. GonaCon causes the host's immune system to bind gonadotropin releasing hormone, preventing ovulation, while SpayVac prevents fertilization of the postovulatory oocyte. This kind of target specificity can be highly advantageous. A number of oocyte-only control contraceptive strategies are currently being researched at the NWRC. 4-Vinylcyclohexene diepoxide (VCD) is an industrial chemical which is specifically ovotoxic, depleting the ovarian oocyte pool with repeated exposure. Research into VCD efficacy as well as the comparability of a similar diepoxide, ERL 4221, in rats and pigs is in progress. Immunological inhibition of recently discovered oocyte-secreted proteins which regulate follicular development in mammals is also of interest. Two such proteins, growth differentiation factor 9 (GDF9) and bone morphogenic protein 15 (BMP15), are highly specific targets for the suppression or elimination of folliculogenesis. These oocyte-specific strategies may offer new, effective alternatives for wildlife contraception. Richard E. Mauldin http://digitalcommons.unl.edu/nwrcinvasive/28 http://digitalcommons.unl.edu/nwrcinvasive/28 Fri, 20 Jun 2008 08:57:34 PDT Two independent studies in the 1990s found that Hawaii had the nation's worst alien pest problem due to gaps in prevention, detection and control programs, which could be addressed through increased communication, cooperation, and public outreach. The Coordinating Group on Alien Pest Species (CGAPS), a government/non-government partnership, formed in 1995 to address these gaps and work on public awareness. Using snakes as an example, a 1996 Hawaii statewide public awareness survey found that 66% of people "had heard of brown treesnakes." CGAPS ran the "Silent Invasion" campaign in 1997, with "shock footage" television commercials and specials about brown treesnakes on Guam. By 2004, awareness of brown treesnakes had risen to 83%, and 91% of Hawaiian residents were "very likely" to report snake sightings, yet less than 5% knew about the Pest Hotline, nobody could recite it, and some balked at having to call an Oahu number to report a snake. CGAPS launched phase two of the campaign in 2006, with television and print media and a new toll-free hotline number. Follow-up surveys confirmed rising awareness about brown treesnakes, but unacceptably low awareness and use of the Pest Hotline. CGAPS is experimenting with ways to promote knowledge and good intentions to different audiences in Hawaii. Christy Martin http://digitalcommons.unl.edu/nwrcinvasive/27 http://digitalcommons.unl.edu/nwrcinvasive/27 Fri, 20 Jun 2008 08:56:04 PDT The house mouse (Mus musculus) has been spread throughout the world by the actions of humans. It causes severe impacts to native ecosystems, especially in areas where there are no native mammals. It is possible to eradicate mice from islands but they are harder to eradicate than rats. A review of reported eradication attempts found that 17 attempts on 45 islands worldwide failed; a failure rate of 38%. The effect of operational factors on eradication success was examined, but no significant model was formed. Brodifacoum is the most widely used toxicant and has a 49% success rate. Mouse eradications should be attempted wherever possible and recommendations to help increase the success of a house mouse eradication attempt are given. James W. B. MacKay http://digitalcommons.unl.edu/nwrcinvasive/26 http://digitalcommons.unl.edu/nwrcinvasive/26 Fri, 20 Jun 2008 08:53:33 PDT The nutria (Myocastor coypus) is a large semi-aquatic rodent, declared as one of the 100 worst invasive species in the world by the IUCN Invasive Species Specialist Group in 2000. Through USDA Small Business Innovative Research Phase I (Mach 2004) and Phase II (Mach 2006) funding, Genesis is developing a new nutria rodenticide as an alternative to the currently-registered zinc phosphide bait. Our course of research and development is described herein: live-trapping, laboratory non-toxic choice studies, laboratory toxicity bioassays, and field toxicity studies. Two active ingredients and two bait types proved to be successful, however, only cholecalciferol in each of two bait types will be tested in future field studies. Jeff J. Mach http://digitalcommons.unl.edu/nwrcinvasive/25 http://digitalcommons.unl.edu/nwrcinvasive/25 Fri, 20 Jun 2008 08:51:14 PDT Invasive, but native to North America, barred owls (Strix varia) are negatively affecting site occupancy, reproduction, and survival of federally threatened northern spotted owls (Strix occidentalis caurina), thereby confounding the land-based conservation strategy for northern spotted owls. Barred owls are moving southward into the range of non-federally listed California spotted owls (S. o. occidentalis), but are not, at this time or in the foreseeable future, a threat to the California spotted owl population. We recommend consideration of barred owl control in the northern Sierra Nevada Mountains, while barred owl numbers are low enough to efficiently eliminate the possibility that they negatively affect California spotted owls outside of the foreseeable future. Kent B. Livezey http://digitalcommons.unl.edu/nwrcinvasive/24 http://digitalcommons.unl.edu/nwrcinvasive/24 Fri, 20 Jun 2008 08:45:46 PDT The introduction of European starlings (Sturnus vulgaris) in New York City in 1890 and 1891 resulted in their permanent establishment in North America. The successful occupation of North America (and most other continents as well) has earned the starling a nomination in the Top 100 list of 'Worlds Worst' invaders. Pimentel et al. (2000) estimated that starling damage to agriculture crops in the United States was $800 million yearly, based on $5/ha damage. Starlings may spread infectious diseases that sicken humans and livestock, costing nearly $800 million in health treatment costs. Lastly, starlings perhaps have contributed to the decline of native cavity-nesting birds by usurping their nesting sites. We describe the life history of starlings, their economic impact on agriculture, and their potential role as vectors in spreading diseases to livestock and humans. We recommend that the database on migratory and local movements of starlings be augmented and that improved baits and baiting strategies be developed to reduce nuisance populations. George M. Linz http://digitalcommons.unl.edu/nwrcinvasive/23 http://digitalcommons.unl.edu/nwrcinvasive/23 Fri, 20 Jun 2008 08:36:13 PDT Relying on headlamp illumination for visual detection of cryptic nocturnal animals may present a challenge. To test how search light properties affect brown treesnake (Boiga irregularis) detection rate, we assigned eight biologists to search for dead snakes placed in roadside vegetation. Each person conducted 4 searches using lamps with varying properties: weak versus strong light, crossed by narrow versus wide beam. On each occasion, 100 snakes were placed randomly along the roadside transect. The mean number spotted per transect search was 13.5. Using an information theoretic approach, sequential order of transect runs was the only confounding variable included in the model with the highest support: 1.5 fewer snakes (95% CI = - 0.4 to -2.5) were found for every sequential transect search a person conducted. A narrow beam spotlight rendered almost seven fewer snakes per search than a broad beam floodlight (95% CI = -4.5 to -9.2). A weak light rendered 4.5 fewer snakes than a strong light (95% CI = -2.1 to -6.9). We suspect that the benefit of using a lamp with a floodlight beam is particularly pronounced when a complex, 3-dimensional forested habitat is surveyed and when the traveling speed is relatively high. Bjorn Lardner http://digitalcommons.unl.edu/nwrcinvasive/22 http://digitalcommons.unl.edu/nwrcinvasive/22 Fri, 20 Jun 2008 08:33:47 PDT Problems associated with managing vertebrate invasive species, defined as any exotic or native species that has spread beyond its natural range, are remarkably common around the world. Although the species may differ, the niches they fill and the damage they generally cause is often consistent. As such, a possibility exists for greater collaboration and harmonization in developing new tools to manage the impacts of invasive species. Moreover, the considerable expense of developing new products, the often onerous registration process, and the lack of return on investment leading to market failure has meant that progress within the field of invasive animal management product development can sometimes be stifled. This paper details a potential way forward using specific examples of ways the Invasive Animals Cooperative Research Centre (IACRC), Pestat P/L, and other IACRC commercial partners aim to provide overseas organizations with humane non-lethal and lethal wildlife management tools. Conversely, we detail overseas-developed products currently being tested in Australia, and a proposal to keep abreast of new developments in other countries to ensure invasive species management within Australasia remains of the highest level. This can only be achieved through truly collaborative research and the global harmonization of registration packages, so product development costs can be minimized and the necessary scales of production can be attained. Steven Lapidge http://digitalcommons.unl.edu/nwrcinvasive/21 http://digitalcommons.unl.edu/nwrcinvasive/21 Fri, 20 Jun 2008 08:30:04 PDT Alien reptiles and amphibians are deserving of greater attention that has hitherto been bestowed upon them by managers and researchers. Eradication or control of established taxa will generally be infeasible, leaving prevention of introductions as the primary management tool for controlling herpetological invasions. I analyzed >5,700 introductions of alien reptiles and amphibians worldwide to obtain the pathway information necessary for design of informed prevention programs. Six pathways account for the large majority of introductions: accidental introductions via cargo and the nursery plant trade and intentional introductions for biocontrol, food use, the pet trade, and aesthetic purposes. Pathway importance varies taxonomically, temporally, and geographically. Unlike other taxa for which introductions have been dominated by either accidental pathways alone or intentional pathways alone, reptile and amphibian introductions involve a mix of both. Consequently, prevention programs must involve a two-pronged approach for these taxa: risk assessment of pathways for taxa introduced accidentally and risk assessment of species for taxa introduced intentionally. Because of variation in pathway importance, information on how taxonomic, temporal, and geographic variables co-vary with economic and social data may allow for predictive assessment of pathway risk for accidental introductions. In contrast, some predictive assessment of taxon risk was achieved using variables that measure climate-matching between native and introduced ranges, phylogenetic risk, and prior history of successful taxon establishment. Fred Kraus http://digitalcommons.unl.edu/nwrcinvasive/20 http://digitalcommons.unl.edu/nwrcinvasive/20 Fri, 20 Jun 2008 08:27:47 PDT Non-target species may be exposed to rodenticides via feeding on rodenticide baits or the carcasses of poisoned target species. As invasive species frequently negatively impact threatened or endangered (T and E) species, there is frequently spatial and temporal overlap of invasive species and T and E species. Risk assessments provide a means to estimate the probability of rodenticide associated adverse effects to non-target species (including T and E species). Quantification of risk provides critical information for decision-makers to weigh the benefits and risks of proposed rodenticide uses and to compare the risks of management with risks associated with no management (e.g. invasive species induced extinction of native species). John Johnston http://digitalcommons.unl.edu/nwrcinvasive/19 http://digitalcommons.unl.edu/nwrcinvasive/19 Fri, 20 Jun 2008 08:23:30 PDT This paper provides a synopsis of the Defenders of Wildlife report entitled Broken Screens: The Regulation of Live Animal Imports in the United States, released in August 2007. That report assessed the complex federal system for regulating live wild animal imports as applied to the 2,241 non-native species that were identified in United States Fish and Wildlife Service records as being imported between 2000 and 2004, inclusive. The report describes the "coarse risk screening" conducted for those species by searching the scientific literature and United States and international databases. If one or more reliable sources indicated a species was known or predicted to be invasive, pose a disease risk, or otherwise be harmful, in the United States or elsewhere, the species was labeled "potentially risky." Due to the hundreds of potentially risky species being imported with no-risk screening by federal officials, the report concludes the United States' regulatory system provides a low level of protection to the nation. Absent major policy reforms, some of the potentially risky, imported animals will escape or be released and form invasive wild populations or cause disease outbreaks. Eleven policy recommendations are offered to reduce these risks to more tolerable levels. Peter Jenkins http://digitalcommons.unl.edu/nwrcinvasive/18 http://digitalcommons.unl.edu/nwrcinvasive/18 Fri, 20 Jun 2008 08:21:16 PDT Geographical Information Systems (GIS) are powerful tools in the field of invasive species management. GIS can be used to create potential distribution maps for all manner of taxa, including plants, animals, and diseases. GIS also performs well in the early detection and rapid assessment of invasive species. Here, we used GIS applications to investigate species richness and invasion patterns in fish in the United States (US) at the 6-digit Hydrologic Unit Code (HUC) level. We also created maps of potential spread of the cane toad (Bufo marinus) in the southeastern US at the 8-digit HUC level using regression and environmental envelope techniques. Equipped with this potential map, resource managers can target their field surveys to areas most vulnerable to invasion. Advances in GIS technology, maps, data, and many of these techniques can be found on websites such as the National Institute of Invasive Species Science (www.NIISS.org). Such websites provide a forum for data sharing and analysis that is an invaluable service to the invasive species community. Tracy Holcombe http://digitalcommons.unl.edu/nwrcinvasive/17 http://digitalcommons.unl.edu/nwrcinvasive/17 Fri, 20 Jun 2008 08:15:18 PDT Cats (Felis catus) brought to Hawaii in the 1700s now occupy most habitats throughout the islands, including montane and sublapine zones. We studied home range, population genetics, diseases, and diet of feral cats on Hawai`i Island. Feral cats on Mauna Kea live in low densities and exhibit some of the largest reported home ranges. While 95% kernel home range estimates for 4 males ( x = 1418 ha) were nearly twice as large as 3 female home ranges ( x = 772 ha), one male maintained a home range of 2050 ha. Population genetics revealed that Mauna Kea may be a source population for feral cats on Mauna Loa and Hawaii Volcanoes National Park (HAVO). Assignment tests provided strong evidence for male-biased dispersal from Mauna Kea to Mauna Loa. Mauna Kea cats exhibited high seroprevalence for toxoplasmosis (37.3%) and feline leukemia virus (FeLV; 16.2%) distributed among all age and sex classes. Feline immunodeficiency virus (FIV) occurred only in adult males comprising 8.8% of the overall population. We found that cats on Mauna Kea primarily consumed birds, present in 69% of digestive tracts, whereas birds were in only 28% of samples from HAVO. Within HAVO, prey use differed between K ī lauea and Mauna Loa. On Mauna Loa, more feral cats consumed small mammals (89%), primarily rodents, than on K ī lauea Volcano (50%). Mice (Mus musculus) were the major component of the feral cat diet on Mauna Loa, whereas Orthoptera were the major component of the diet on K ī lauea. A digestive tract from Mauna Loa contained a mandible set, feathers, and bones of an endangered Hawaiian Petrel (Pterodroma sandwichensis). Abundant birds on Mauna Kea may maintain large numbers of feral cats that disperse long distances. Abundant rodents found in Mauna Loa digestive tracts may also support cats that then take advantage of breeding petrels. Steven C. Hess http://digitalcommons.unl.edu/nwrcinvasive/16 http://digitalcommons.unl.edu/nwrcinvasive/16 Fri, 20 Jun 2008 08:07:52 PDT The ruddy duck (Oxyura jamaicensis) was introduced to wildfowl collections in the United Kingdom (UK) in the 1940s and subsequently escaped into the wild. Estimated numbers have increased rapidly in the UK from 20 wintering birds in 1962 to 5,946 in January 2000. As the population of feral ruddy ducks in the UK rose, so did the number of records of ruddy ducks on the European mainland. In 1984, ruddy ducks were first recorded in Spain, which is home to internationally important populations of the rare indigenous white-headed duck (Oxyura leucocephala). By 1991, hybrids resulting from crosses between the two species were recorded in that country. The two species hybridize readily, with the ruddy duck apparently possessing the competitive advantage. The ruddy duck is now recognized as the most significant threat to the white-headed duck and the UK appears to be the main source of birds reaching mainland Europe. This paper details the development of a control and then an eradication program for this species in the UK. Iain Henderson http://digitalcommons.unl.edu/nwrcinvasive/15 http://digitalcommons.unl.edu/nwrcinvasive/15 Fri, 20 Jun 2008 08:01:51 PDT The brown treesnake (Boiga irregularis) was introduced on Guam during post World War II cargo movements. Brown treesnakes (BTS) have now become exceptionally abundant on Guam and pose a direct, significant, and growing threat to other areas outside of their historic range, including the Commonwealth of the Northern Mariana Islands (CNMI), the State of Hawaii, the United States mainland and other sites regionally and internationally. The CNMI is at high risk for a BTS introduction due to its close proximity and the types and amount of cargo received. Limited BTS awareness efforts between 1986 and 2002 in the CNMI resulted in an average response time of 126 hours indicating that an increased awareness of appropriate response actions among the public was needed. An awareness campaign was outlined in three phases: (1) baseline public survey, (2) ten month awareness campaign, and (3) re-evaluation survey. The CNMI Division of Fish and Wildlife (DFW) staff and an outside advertising firm created a baseline survey to gather media consumption information and environmental attitudes. Conclusions of the baseline survey were then utilized to create a ten month awareness campaign to improve average response times. After the campaign, average response times decreased from 126 hours to 1 hour 42 minutes. The re-evaluation survey confirmed the success of specific campaign components and directs current awareness efforts. Nathaniel B. Hawley http://digitalcommons.unl.edu/nwrcinvasive/14 http://digitalcommons.unl.edu/nwrcinvasive/14 Fri, 20 Jun 2008 07:58:31 PDT Florida has more non-native wildlife species than any other state: 439 introduced species of fish, wildlife and marine organisms have been observed and at least 123 are established, i.e., highly unlikely to be extirpated without human intervention. Florida is an epicenter for non-native species with a long established pet industry, major tourist attractions, and major ports, primarily Miami. The large number of established species is due to climate match with that of popular tropical pets, habitat disturbance that facilitates invasion, and a depauperate vertebrate fauna in tropical and subtropical portions of Florida. The Florida Fish and Wildlife Conservation Commission's approach to managing non-native wildlife is based on (1) encouraging responsible pet ownership; (2) a regulated industry is preferable to underground traffic; and (3) most introduced species have negligible environmental impacts. Regulations for captive wildlife and non-native aquatic species, first established in the 1970s, employ risk-based bio-security for problematic species, and prohibition of a limited number of species that posed unacceptable risks to the ecosystem, economy, or human health and safety. Effective January 1, 2008, owners of six large reptile species will be required to implant passive integrated transponders to identify individual animals. Although anecdotal evidence suggests dealers have released inventories to establish source populations, the majority of introductions have resulted from release of pets by owners. To close this pathway, a pet surrender network is in the early stages of development. Within the past five years, capacity to detect and manage terrestrial and semi-aquatic species has improved, including surveillance, rapid assessment and response; examples include the Gambian giant pouched rat (Cricetomys gambianus), purple swamphen (Porphyrio porphyrio), and Argentine black and white tegu (Tupinambis merianae). Scott Hardin http://digitalcommons.unl.edu/nwrcinvasive/13 http://digitalcommons.unl.edu/nwrcinvasive/13 Thu, 19 Jun 2008 11:45:07 PDT The effects of invasive vertebrate species on agriculture, human health and safety, and the environment are a growing concern around the world. The number of incidents of invasive species causing harm continues to climb with increased worldwide travel and transportation of goods. The focus for many decades was on invasive pathogens, plants, and invertebrates because they can greatly affect human and animal health and food supplies. In recent years, invasive vertebrate species, such as rats, feral pigs, and feral cats, have garnered more attention because the magnitude of their impacts have been repeatedly highlighted in the media. In response, better methods of prevention, detection, and management of invasive species have been developed. For example, several eradications of invasive vertebrates on islands have been successful, although management on mainland settings is generally much more challenging. Gary W. Witmer http://digitalcommons.unl.edu/nwrcinvasive/12 http://digitalcommons.unl.edu/nwrcinvasive/12 Thu, 19 Jun 2008 11:41:26 PDT Black-tailed jackrabbits are a prolific, mobile species that became established at Miami International Airport, Florida. These animals posed a potential threat for colonization through additional parts of Florida if they were able to spread beyond the expansive airport property. Moreover, their carcasses from collisions with vehicles and aircraft attracted large scavenging and predatory birds to the airport, causing potential airstrike hazards. While the jackrabbits ultimately were successfully eradicated, the political, economic and management paths to that success were convoluted. We describe that history here and how a beneficial outcome was ultimately achieved. Richard M. Engeman http://digitalcommons.unl.edu/nwrcinvasive/11 http://digitalcommons.unl.edu/nwrcinvasive/11 Thu, 19 Jun 2008 11:36:15 PDT A thriving population of Gambian giant pouched rats became established on Grassy Key, a 550-ha island in Florida, following escape(s) from an exotic pet breeder. After existence of the population was verified, computer models indicated that Gambian giant pouched rats could successfully invade a large portion of North America if they reached the mainland. This largest of rat species is highly prolific, and its dispersal to the mainland could result in substantial negative impacts to agriculture, environment, and wildlife. Additionally, Gambian giant pouched rats are known vectors of a variety of diseases transmissible to humans and livestock. The first action to counter the severe and immediate threat of dispersal was to rapidly develop the information necessary on which to base an eradication program. The information included detection and monitoring technologies, population indexing methodologies, population distribution, habitat preferences, trapping methodology, acceptance of bait matrices, and efficacy tests of toxicants, and bait stations that minimize exposure to native species. With these tools forming a foundation, a pilot eradication was funded for Crawl Key, a 150-ha key adjoining Grassy Key to which the species expanded its range. The aims of the pilot eradication were to test and fine-tune the methods prior to implementing full-scale eradication on Grassy Key. No Gambian giant pouched rats were found in two subsequent surveys of Crawl Key. Further surveys of Grassy Key were used to refine bait station densities for the full scale eradication effort implemented on Grassy Key in spring 2007. The eradication effort is on-going. Gary W. Witmer http://digitalcommons.unl.edu/nwrcinvasive/10 http://digitalcommons.unl.edu/nwrcinvasive/10 Thu, 19 Jun 2008 11:30:41 PDT The introduction of rodents on an island as a new predator usually interferes with natural island biodiversity, particularly on islands without any native mammalian predators. Many Alaskan islands, and most islands in the Aleutian Island region of the Alaska Maritime National Wildlife Refuge (AMNWR), are free of mammalian predators and are vulnerable to invasion by rodents. Rat introduction to islands can put ground-nesting birds, such as seabirds and endemic landbirds, at risk of extirpation. The refuge is also concerned about additional introductions of house mice. As far as we know, the introduction, or "spilling," of rats onto refuge islands from ships and cargo was accidental, but probably preventable. This paper is about preventing new rodent invasions, especially rats, on Alaskan islands from shipwrecks, and using our experience on AMNWR as a basis for recommendations about improvements in the future. Steven M. Ebbert http://digitalcommons.unl.edu/nwrcinvasive/9 http://digitalcommons.unl.edu/nwrcinvasive/9 Thu, 19 Jun 2008 11:27:09 PDT The management of the invasive feral pig (Sus scrofa) has been the subject of intense study in recent years. Feral pigs are also susceptible to diseases (e.g., brucellosis, pseudorabies) that can be transmitted to livestock, humans, and wildlife. Feral pigs clearly represent a threat to the sustainability of multiple agriculture products. Population reduction (trapping or shooting) is the best current alternative for controlling pig damage. However, reduction is crude and inefficient in terms of manpower and resources because pigs from neighboring areas quickly recolonize managed areas. We used a panel of 9 microsatellite loci to study broad-scale population structure in feral pigs from south Texas and to evaluate recolonization after a local removal. At a broad scale (>200 km), pig populations displayed a moderate degree of genetic structure (Fst = 0.16), suggesting that at broad geographic scales, populations are differentiated enough to be functionally independent. However, genetic similarity was not a simple function of geographic distance, implying that movement and dispersal are not equal among populations. This may be due to the presence of terrain features that promote (e.g., river systems) or inhibit (e.g., urban areas, farmland areas) dispersal. At a local scale, animal samples taken before and after a removal event were genetically different (Fst = 0.08), indicating rapid recolonization occurred into the controlled area. Overall, our results indicate that knowledge of population structure in south Texas could be used to improve pig control efforts, but high rates of movement and dispersal in other areas would likely require control efforts over a very broad region, possibly an entire watershed. Ongoing efforts will attempt to identify fine-scale genetic structure and landscape features that could be used to focus management efforts. Johanna Delgado-Acevedo http://digitalcommons.unl.edu/nwrcinvasive/8 http://digitalcommons.unl.edu/nwrcinvasive/8 Thu, 19 Jun 2008 11:23:00 PDT Eradication of invasive vertebrate pests from increasingly large islands has become an important wildlife management and conservation tool internationally. Success on islands has prompted attempts to exclude and eradicate vertebrate pests from mainland sites. Early mainland exclusion efforts often failed due to ineffective or poorly maintained barriers to pest reinvasion. Over the last 10 years, we have conducted extensive experiments to design effective pest exclusion technology. We have determined the behavior and physical abilities of many of the vertebrate pest species found in New Zealand and other parts of the world. Pest species have been tested against a variety of fence designs with the aim of developing 100% effective barriers. We found that fences which relied on the use of electrified wires proved ineffective for most species, whereas barriers that exceeded the physical capability of the target pests were reliable. Two multispecies fence designs excluded every pest tested. The designs excluded rodents (including mice), lagomorphs, mustelids, hedgehogs, brushtail possums, cats, dogs, feral pigs, goats, deer, Javan macaque and domestic livestock. The outcome of this research program has been the commercial availability of two designs of Xcluder pest proof fence. Supporting components and technology, such as pest-free pedestrian and vehicle gates, waterway gates and remote surveillance systems to mitigate reinvasion risks have enabled projects to succeed. Over 20 exclusion barrier systems have now been constructed in areas up to 3,400 ha in size and have allowed multi-species eradication attempts. With the successful removal of vertebrate pests, many projects are now undertaking significant restoration programs including the reintroduction of threatened wildlife species to mainland sites. Tim Day http://digitalcommons.unl.edu/nwrcinvasive/7 http://digitalcommons.unl.edu/nwrcinvasive/7 Thu, 19 Jun 2008 11:20:54 PDT The use of extreme temperatures is one of the few chemical residue-free techniques available for control of pest species and has proven fast and effective in a variety of applications. We determined the upper and lower lethal temperatures for the brown treesnake. We also investigated whether gender, size, body condition and exposure time influenced survival at temperature extremes. Elevating snake core temperatures to 40°C and 41°C for one hour resulted in 99% mortality within seven days (40°C) and 100% mortality within one hour of exposure (41°C). Mortality decreased sharply to 51% for a one hour exposure to 39°C. Shorter, heavier snakes were more susceptible to extreme hot temperatures, but gender had no effect. The lower lethal temperature was established at a body temperature of -5°C held for one hour. Males were more susceptible to extreme cold than females, as were snakes with lower body condition. These results imply that brown treesnakes are slightly more vulnerable than many invertebrate pests, suggesting that hot thermal fumigation would not require exceptional treatments and should be feasible for shipments containing most non-biological materials and some biological ones (e.g., some live plants, grain), and cold thermal fumigation should be feasible for all materials tolerant of being frozen. Michelle T. Christy http://digitalcommons.unl.edu/nwrcinvasive/6 http://digitalcommons.unl.edu/nwrcinvasive/6 Thu, 19 Jun 2008 11:16:17 PDT Prevention is the best policy for dealing with introduced species. However, biologists often spend an inordinate amount of time studying their spread and impacts rather than focusing on what should be done to thwart their establishment in the first place. Amphibian and reptile introductions are reaching epidemic proportions in Florida, largely due to irresponsible behavior by pet owners and the pet industry, but also due to ineffective preventive policies and actions. Prevention of additional amphibian and reptile introductions in Florida will require a comprehensive approach involving legal restrictions of certain problematic species, a massive public education effort, and a well-funded and staffed Early Detection and Rapid Response (EDRR) program. EDRR is not a novel concept, but it needs to be newly applied to amphibian and reptile introductions where pathways are firmly established and propagule pressure is intense. An effective EDRR program in Florida will require (1) significant funding and political will, (2) a comprehensive stakeholder education and public outreach program, (3) a vast network of expert early detectors, (4) a team of talented rapid responders, and (5) rigorous post-project assessment. Knowledge gained from such a program in Florida could easily be extended to other taxonomic groups and locations. Todd S. Campbell http://digitalcommons.unl.edu/nwrcinvasive/5 http://digitalcommons.unl.edu/nwrcinvasive/5 Thu, 19 Jun 2008 11:14:08 PDT Greetings and welcome to Fort Collins. We at the National Wildlife Research Center (NWRC) have had the privilege of organizing and hosting four international symposia since 1993. The first three were on the topics of contraception and wildlife, repellents in wildlife management, and the economics of wildlife damage management. Today, it is my pleasure to welcome you to our fourth symposium: the International Symposium on Managing Vertebrate Invasive Species. I know our Symposium's organizing committee has strived to bring you a diverse group of international speakers.all of whom are working on the cutting edge of invasive species research, management, and eradication. More specifically, much work is being done in the areas of early detection, rapid response, biological and economic impacts, prevention and control, resource recovery, public education and support, and global initiatives. Richard L. Bruggers http://digitalcommons.unl.edu/nwrcinvasive/4 http://digitalcommons.unl.edu/nwrcinvasive/4 Thu, 19 Jun 2008 11:11:38 PDT New Zealand is an archipelago with many islands of conservation significance, none of which has the full suite of invasive vertebrate pests found on mainland New Zealand. Managing invasive species on New Zealand islands involves prevention of pests establishing and controlling or extirpating those already there. Prevention measures, referred to as island biosecurity, focuses on the three major pathways for pests to arrive: deliberate release, accidental release and swimming. Managing deliberate release is largely reactive but does have opportunities for prevention depending on the motivation of offenders. Managing accidental release is where most proactive work is done by Department of Conservation staff to protect remote high-value nature reserve islands. A comprehensive quarantine, surveillance and contingency response system is in place for these sites. When managing self introductions, the size and nature of the water gap and the species involved largely determine the risk. Many islands are beyond the swimming range of all pests, but for some closer ones, we are exploring the feasibility, costs and benefits of managing reinvasion across various water gaps and trying to improve our detection and elimination techniques. Eradication backed up by successful ongoing island biosecurity in many cases compares well with alternative management options at mainland sites. Keith Broome http://digitalcommons.unl.edu/nwrcinvasive/3 http://digitalcommons.unl.edu/nwrcinvasive/3 Thu, 19 Jun 2008 11:10:34 PDT Major introductions of roof rats (Rattus rattus) likely occurred in the ports of East Africa during the Third Plague Pandemic in the late 1800's. Transport via trains, boats, and trucking likely introduced this species to inland areas of East Africa, ultimately including Northwest Uganda. Historic plague outbreaks occurred during the early part of the 20th century and continue to cause a human disease burden in the West Nile region of NW Uganda via the bubonic, septicemic, and pneumonic forms. Four field sites in this area were trapped to determine the rodent species composition in commensal and peridomestic areas of villages and associated flea burdens of the rodents. Rattus rattus were the most prevalent rodent trapped in commensal areas followed by the Nile rat (Arvicanthis niloticus). The most common peridomestic species of rodent was the Nile rat. Other peridomestic rodent species captured included, Mastomys natalensis, Lophuromys flavopunctatus, L. sikapusi, Gerbil (Tatera spp.), Lemniscomys spp., and 4 unknown species. Flea burdens on commensal R. rattus averaged 1.7±1.2 fleas per animal and on all peridomestic rodents, average 2.0±0.7 per animal. Additionally, commensal areas were sampled to determine free-living flea populations. Burrow swabbing indicated an average 0.19±0.12 fleas/burrow. Lighted flea traps averaged 1.3±0.6 fleas per household and dark flea traps averaged 0.5±0.4 fleas per household. Jeff N. Borchert http://digitalcommons.unl.edu/nwrcinvasive/2 http://digitalcommons.unl.edu/nwrcinvasive/2 Thu, 19 Jun 2008 11:06:27 PDT European starlings (Sturnus vulgaris) are one of the most abundant and widespread bird species on earth. Introduced to Australia in the late 1850s, their highly adaptive ecology has enabled them to become a major pest. Concerns include public health and safety, economic impacts, detrimental environmental effects, and bird strikes at airports. Unfortunately current Australian control methods are ineffective and more efficacious, humane methods need to be developed. A feasibility study was undertaken of the likely risks/benefits of avicide DRC 1339 (3-chloro-4-methylbenzenamine hydrochloride) in Australia. This included a risk-analysis, a multi-industry survey and non-toxic bait trials to assess target-specificity. Results indicated that European starlings were one of three key bird species affecting intensive agriculture; there was strong support for better bird control techniques; and the risk to 82% of the native bird species recorded at the test sites was assessed as low or very low. Potential bait carrier trials demonstrated behavioral differences between United States and Australian starlings and hence the main application will initially be restricted to sites such as intensive livestock production facilities where starlings are already accustomed to feeding. Therefore, the project now aims to demonstrate DRC 1339 efficacy under Australian conditions and achieve registration. Tina Bentz http://digitalcommons.unl.edu/nwrcinvasive/1 http://digitalcommons.unl.edu/nwrcinvasive/1 Thu, 19 Jun 2008 11:01:20 PDT Florida has a mild climate, diverse natural habitats, and a growing, mobile human population. Florida also hosts thousands of species of introduced plants, fish, and wildlife. A recent compilation lists 196 non-native bird species, comprising 15 orders, which have occurred in Florida. The list includes 72 species of parrots and parakeets (psittaciformes), 51 passerines, and 22 species of waterfowl (anseriformes). First sightings of newly introduced bird species in Florida increased rapidly through the 1980s, but numbers of new species detected appear to have subsided since then. Sources of introductions are often not reported, but of those that are known, most derive from intentional releases (e.g., for hunting) or escapes from private collections, parks, or zoos. Based on this list and other sources within the state, we identified 14 non-native bird species now considered to be established in Florida. We review those species in particular, and discuss impacts that they are having. We use Christmas Bird Count data to examine geographic and temporal patterns of non-native bird occurrence within the state. We identify additional non-native bird species that are emerging as potentially serious management problems in Florida, and we recommend actions for efficient, effective management of non-native bird issues. Michael L. Avery