Digital Commons Network^™

Foot-And-Mouth Disease In Feral Swine: Susceptibility And Transmission, F. Mohamed, S. Swafford, H. Petrowski, A. Bracht, B. S. Schmit, A. Fabian, J. M. Pacheco, E. Hartwig, M. Berninger, C. Carrillo, G. Mayr, K. Moran, D. Kavanaugh, H. Leibrecht, W. White, S. Metwally

United States Department of Agriculture Wildlife Services: Staff Publications

Experimental studies of foot-and-mouth disease (FMD) in feral swine are limited, and data for clinical manifestations and disease transmissibility are lacking. In this report, feral and domestic swine were experimentally infected with FMDV (A24-Cruzeiro), and susceptibility and virus transmission were studied. Feral swine were proved to be highly susceptible to A-24 Cruzeiro FMD virus by intradermal inoculation and by contact with infected domestic and feral swine. Typical clinical signs in feral swine included transient fever, lameness and vesicular lesions in the coronary bands, heel bulbs, tip of the tongue and snout. Domestic swine exhibited clinical signs of the disease within …

Biological, Technical, And Social Aspects Of Applying Electrified Fladry For Livestock Protection From Wolves (Canis Lupus), N. J. Lance, S. W. Breck, C. Sime, P. Callahan, J. A. Shivik

United States Department of Agriculture Wildlife Services: Staff Publications

Context. Wolf predation on livestock can cause economic hardship for livestock producers as well as reduce tolerance for wolves. Lethal control of wolves is often controversial; thus, development of effective non-lethal methods for reducing wolf–livestock conflict is important. Electrified fladry is a new tool that is similar to fladry (i.e. a barrier system that scares wolves), but electrified fladry also incorporates an electric shock designed to decrease the potential for wolves to habituate to the barriers.

Aim. Evaluation of electrified fladry requires understanding of its effectiveness relative to fladry and the costs and benefits of applying it in …

Comparative Toxicity Of Diphacinone To Northern Bobwhite (Colinus Virginianus) And American Kestrels (Falco Sparverius), Barnett A. Rattner, Katherine E. Horak, Sarah E. Warner, Daniel D. Day, John J. Johnston

United States Department of Agriculture Wildlife Services: Staff Publications

The acute oral toxicity of the anticoagulant rodenticide diphacinone was found to be about 20 times greater to American kestrels (LD₅₀=97 mg/kg) than to northern bobwhite (LD₅₀=2,014 mg/kg). Several precise and sensitive clotting assays (prothrombin time, Russell’s Viper venom time, thrombin clotting time) were adapted for use in these species, and this combination of assays is recommended to detect effects of diphacinone and other rodenticides on coagulation. Oral administration of diphacinone over a range of doses (sublethal to the extrapolated LD₁₅) prolonged prothrombin time and Russell’s Viper venom time within 24 to 48 hrs …

The Use Of Liver Microsome In-Vitro Methods To Study Toxicant Metabolism And Predict Species Efficacy, Katherine E. Horak, Chad R. Wermager, Thomas M. Primus

United States Department of Agriculture Wildlife Services: Staff Publications

Liver microsomes are used extensively in human pharmaceutical development to study the metabolism of compounds of interest; however, they are rarely part of the development of toxicants for the control of wildlife. Liver microsome samples from wildlife of interest would likely be harvested in the field without access to laboratory perfusion equipment. Therefore, the metabolic activity of microsomes from perfused and non-perfused livers was compared. There was no significant difference in diphacinone metabolism by liver microsomes from both perfused and non-perfused Wistar rat livers, although chlorophacinone metabolism was significantly different. There are often significant differences in metabolism between species that …

Wildlife Conservation Sunflower Plots And Croplands As Fall Habitat For Migratory Birds, Heath M. Hagy, George M. Linz, William J. Bleier

United States Department of Agriculture Wildlife Services: Staff Publications

Agricultural fields are often overlooked as post-breeding and migratory bird habitat, even though many species use row-crop fields in the northern Great Plains. We monitored bird use, crop and non-crop vegetation characteristics and abundance, and land use around (≤2.4 km) 35 8-ha Wildlife Conservation Sunflower Plots (WCSP) and one commercial sunflower and non-sunflower row-crop field, paired with each WCSP, in fall 2004 and 2005. We excluded four species of blackbirds from our analysis that commonly form large foraging flocks and ubiquitously use agricultural fields. A diverse community of migratory birds used WCSP and commercial sunflower compared to other non-sunflower crops …

Evolving Analyses Of The Shoshone River Skunk Rabies Epizootic In Wyoming, Craig A. Ramey, Kenneth H. Mills, Justin W. Fischer

United States Department of Agriculture Wildlife Services: Staff Publications

A rabies epizootic occurred in striped skunks from 1988-1993 in a previously rabies-free area of northwestern Wyoming. USDA APHIS Wildlife Services (WS) cooperated with state and local officials by providing a rabies monitoring and depopulation program starting in 1990. Wyoming WS asked for assistance in 1991 from the National Wildlife Research Center (NWRC) to analyze the epizootic’s movements. The goal was to address the public’s concerns about their health and safety and that of their domestic animals and livestock. All rabid skunks were diagnosed by the Wyoming State Veterinary Laboratory (WSVL) using standardized fluorescent antibody testing of brain tissues. The …

American Bullfrogs As Invasive Species: A Review Of The Introduction, Subsequent Problems, Management Options, And Future Directions, Nathan P. Snow, Gary W. Witmer

United States Department of Agriculture Wildlife Services: Staff Publications

Native to the eastern United States, American bullfrogs have been introduced throughout the western U.S. and to several other countries and islands around the world. Bullfrogs are well adapted for many of the permanent water sources that occur within the U.S., and once introduced, they typically become dominant. Because of their large size and voracious appetite, bullfrogs outcompete and prey upon many indigenous species. They are hypothesized to be cause significant negative impacts, which may contribute to the endangerment and extinction of some sensitive species. There are few, if any, effective and efficient control methods to manage invasive bullfrogs. Current …

Enzymatic Digestion Of Chronic Wasting Disease Prions Bound To Soil, Samuel Saunders, Jason C. Bartz, Kurt C. Vercauteren, Shannon L. Bartelt-Hunt

United States Department of Agriculture Wildlife Services: Staff Publications

Chronic wasting disease (CWD) and sheep scrapie can be transmitted via indirect environmental routes, and it is known that soil can serve as a reservoir of prion infectivity. Given the strong interaction between the prion protein (PrP) and soil, we hypothesized that binding to soil enhances prion resistance to enzymatic digestion, thereby facilitating prion longevity in the environment and providing protection from host degradation. We characterized the performance of a commercially available subtilisin enzyme, Prionzyme, to degrade soil-bound and unbound CWD and HY TME PrP as a function of pH, temperature, and treatment time. The subtilisin enzyme effectively degraded PrP …

Feral Swine Behavior Relative To Aerial Gunning In Southern Texas, Tyler A. Campbell, David Long, Bruce Leland

United States Department of Agriculture Wildlife Services: Staff Publications

Feral swine (Sus scrofa) impact resources through their destructive feeding behavior, competition with native wildlife, and impacts to domestic animal agriculture. We studied aerial gunning on feral swine to determine if aerial gunning altered home range and core area sizes, distances between home range centroids, and distances moved by surviving individuals. We collected data before, during, and after aerial gunning in southern Texas. Using Global Positioning System collars deployed on 25 adult feral swine at 2 study sites, we found home range and core area sizes did not differ before and after aerial gunning. However, feral swine moved …

The Economic Impacts To Commercial Farms From Invasive Monkeys In Puerto Rico, Richard M. Engeman, Jose´ E. Laborde, Bernice U. Constantin, Stephanie A. Shwiff, Parker Hall, Anthony Duffiney, Freddie Luciano

United States Department of Agriculture Wildlife Services: Staff Publications

Beginning in the 1930s and continuing through the 1970s, rhesus macaques and patas monkeys were introduced to presumed secure locations, primarily coastal islets, in Puerto Rico. Escapes into the wild began almost immediately after introduction. Today the combined range of the two species covers approximately 600 km² of southwestern Puerto Rico, where serious conflicts with agricultural interests have resulted. The Puerto Rico Department of Agriculture surveyed about 90% of commercial farmers in the range of the monkeys to begin quantifying damage by monkeys and the associated economic losses during the years 2002–2006. During that time, total economic losses by …

An Evaluation Of Diazacon As A Potential Contraceptive In Non-Native Rose-Ringed Parakeets, Mark Lambert, Giovanna Massel, Christi Yoder, David Cowan

United States Department of Agriculture Wildlife Services: Staff Publications

Rose-ringed parakeets (Psittacula krameri) have become widely established outside their native range through accidental or deliberate release. Potential economic impacts on agriculture, conservation concerns, and mixed public opinion regarding the species have highlighted the need to develop effective but humane management options. Fertility control might provide such a solution if a safe and environmentally benign contraceptive was available. The chemical 20,25-diazacholesterol dihydrochloride (diazacon) has previously been used to reduce reproductive output in avian species through reduction of blood cholesterol and cholesterol-dependent reproductive hormones. We orally dosed captive rose-ringed parakeets with a solution of either 9 mg/kg or 18 …

Evaluation Of Feral Swine- Specific Feeder Systems, David B. Long, Tyler A. Campbell, Giovanna Massei

United States Department of Agriculture Wildlife Services: Staff Publications

Feral swine (Sus scrofa) have been introduced across many portions of the globe, including rangeland ecosystems of the United States. Feral swine populations are expanding because of their adaptability, high reproductive potential, and because they are (accidentally and intentionally) released by humans. Today, feral swine are the most abundant exotic ungulate in the United States.

Rangeland ecosystems are impacted by feral swine primarily through soil disturbance caused by rooting activities. Within these systems, natural disturbances (e.g., burrowing, grazing by native animals, and periodic fire) generally increase or maintain species diversity. However, rooting by feral swine often occurs at …

The Earliest House Sparrow Introductions To North America, Michael P. Moulton, Wendell P. Cropper Jr., Michael L. Avery, Linda E. Moulton

United States Department of Agriculture Wildlife Services: Staff Publications

Several authors have argued that three separate introductions of roughly 100 individuals were required initially to establish the House Sparrow (Passer domesticus) in the Brooklyn, New York area. We argue that these claims are in error and that the actual record suggests that it is likely the initial introduction of just 16 birds in 1851 was all that was required to establish the species in New York. We further suggest that a similar level of scrutiny of historical records will reveal more examples of misinterpretations and errors, casting doubt on the validity of studies that claim propagule pressure …

Test Of Localized Management For Reducing Deer Browsing In Forest Regeneration Areas, Brad F. Miller, Tyler A. Campbell, Ben Laseter, W. Mark Ford, Karl Miller

United States Department of Agriculture Wildlife Services: Staff Publications

White-tailed deer (Odocoileus virginianus) browsing in forest regeneration sites can affect current and future stand structure and species composition. Removal of deer social units (localized management) has been proposed as a strategy to alleviate deer overbrowsing in forest systems. We conducted an experimental localized removal in a high-density deer population in the central Appalachians of West Virginia, USA, during winter 2002. We removed 51 deer within a 1.1-km² area that encompassed 2 forest regeneration sites (14 ha). During the summer following removal, we detected decreases in distance from the removal area in 8 of 30 (26.7%) adult …

The Versatility Of Graded Acoustic Measures In Classification Of Predation Threats By The Tufted Titmouse Baeolophus Bicolor: Exploring A Mixed Framework For Threat Communication, Kathryn E. Sieving, Stacia A. Hetrick, Michael L. Avery

United States Department of Agriculture Wildlife Services: Staff Publications

Many mammal and bird species respond to predator encounters with alarm vocalizations that generate risk-appropriate responses in listeners. Two conceptual frameworks are typically applied to the information encoded in alarm calls and to associated anti-predator behaviors. ‘Functionally referential’ alarm systems encode nominal classes or categories of risk in distinct call types that refer to distinct predation-risk situations. ‘Risk-based’ alarms encode graded or ranked threat-levels by varying the production patterns of the same call types as the urgency of predation threat changes. Recent work suggests that viewing alarm-response interactions as either referential or risk-based may oversimplify how animals use information in …

Potential Attractants For Detecting And Removing Invading Gambian Giant Pouched Rats (Cricetomys Gambianus), Gary W. Witmer, Nathan P. Snow, Patrick Burke

United States Department of Agriculture Wildlife Services: Staff Publications

BACKGROUND: Native to Africa, Gambian giant pouched rats (Gambian rats; Cricetomys gambianus Waterh.) are a threatening invasive species on a Florida island, Grassy Key. Gambian giant pouched rats shifted from a domestic pet to invading species after suspected release from a pet breeder. Because of the large size of Gambian rats (weighing up to 2.8 kg), they pose a serious threat to native species (particularly nesting species) and agricultural crops, especially if Gambian rats invade mainland Florida. Also, Gambian rats pose a threat from disease, as they were implicated in a monkeypox outbreak in the mid-western United States in 2003. …

Capture Of Ungulates In Central Asia Using Drive Nets: Advantages And Pitfalls Illustrated By The Endangered Mongolian Saiga Saiga Tatarica Mongolica, Joel Berger, Kim M. Murray, Bayarbaatar Buuveibaatar, Mike R. Dunbar, Badamjav Lkhagvasuren

United States Department of Agriculture Wildlife Services: Staff Publications

The study of mammals suffering intense poaching in remote areas poses an increasingly difficult conservation challenge, in part because the extreme flightiness of such species complicates safe capture. The benefits of handling (an opportunity to obtain biological information and attach radio collars) must be weighed against stress to the animals and potential capture-related mortality. In parts of Central Asia this problem is not trivial, as populations have been heavily harvested and opportunities for restraint are often limited. Mongolian saiga Saiga tatarica mongolica, being both Endangered and poached, typifies these issues. Here we describe capture protocols for adult females handled …

Mite-Filled Cyst On A Brown-Headed Cowbird (Molothrus Ater) In Florida, Usa, Marilyn G. Spalding, James W. Mertins, Matthew J. Reetz, Kandy L. Keacher, Michael L. Avery, Ellis C. Greiner

United States Department of Agriculture Wildlife Services: Staff Publications

A large, partly pedunculated mass on the scapular area of a wild-caught captive Brown-headed Cowbird (Molothrus ater) consisted of a multiloculated keratin cyst inhabited by a new species of harpirhynchid mite (Harpirhynchus quasimodo). The mass did not interfere with flight or behavior. This is the first record of such an infestation of cowbirds in Florida.

Evaluating Commercially Available Rodenticide Baits For Invasive Gambian Giant Pouched Rats (Cricetomys Gambianus), Gary W. Witmer, Nathan P. Snow, Patrick W. Burke

United States Department of Agriculture Wildlife Services: Staff Publications

Gambian giant pouched rats (Cricetomys gambianus) are native to Africa, but they are popular in the pet industry in the United States. They were reservoir hosts during a monkeypox outbreak in the Midwestern United States in 2003. A free-ranging population became established on Grassy Key in the Florida Keys, apparently because of a release by a pet breeder. These rodents could cause significant damage to agricultural crops should they reach the mainland. Research under controlled conditions was needed to identify effective rodenticides for Grassy Key or other cases where an invasion of Gambian rats might occur. We tested …

Identification And Management Of Wildlife Damage, Kurt C. Vercauteren, Richard A. Dolbeer, Eric M. Gese

United States Department of Agriculture Wildlife Services: Staff Publications

Wildlife management is often thought of in terms of protecting, enhancing, and nurturing wildlife populations and the habitat needed for their well-being. However, many species at one time or another require management actions to reduce conflicts with people, other wildlife species, or other resources. Examples include an airport manager modifying habitats to reduce gull (family Laridae) activity near runways, a forester poisoning pocket gophers (family Geomyidae) to increase tree seedling survival in a reforestation project, or a biologist trapping an abundant predator or competing species to enhance survival of an endangered species. These are just a few of many examples …

Promiscuous Mating In Feral Pigs (Sus Scrofa) From Texas, Usa, Johanna Delgado-Acevedo, Angeline Zamorano, Randy W. Deyoung, Tyler A. Campbell, David G. Hewitt, David B. Long

United States Department of Agriculture Wildlife Services: Staff Publications

Context. Feral pigs represent a significant threat to agriculture and ecosystems and are disease reservoirs for pathogens affecting humans, livestock and other wildlife. Information on the behavioural ecology of feral pigs might increase the efficiency and effectiveness of management strategies.

Aims. We assessed the frequency of promiscuous mating in relation to oestrous synchrony in feral pigs from southern Texas, USA, an agroecosystem with a widespread and well established population of feral pigs. An association between multiple paternity of single litters and synchrony of oestrous may indicate alternative mating strategies, such as mateguarding.

Methods. We collected gravid sows at …

Response Of Deer To Containment By A Poly-Mesh Fence For Mitigating Disease Outbreaks, Michael J. Lavelle, Justin W. Fischer, Scott E. Hygnstrom, Joshua J. White, Aaron M. Hildreth, Gregory E. Phillips, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

Rapidly deployable and effective methods are needed to contain free-ranging deer (Odocoileus spp.) during acute disease outbreaks. We evaluated efficacy of a 2.1-m-tall polypropylene mesh (poly-mesh) fence for containing ≥15 free-ranging white-tailed deer (O. virginianus) within a 42-ha area in eastern Nebraska, USA. We observed a 99% decrease in deer leaving the enclosure area after we installed fencing (1 deer jumped; 0.02 deer/hr) compared with prefence rates (5.26 deer/hr). However, 8 deer (53% of censused population) escaped the enclosure during a census drive after our study. Poly-mesh fencing may be effective in temporarily containing free-ranging deer during …

Multi-Year Fertility Reduction In Free-Roaming Feral Horses With Single-Injection Immunocontraceptive Formulations, Meeghan E. Gray, David S. Thain, Elissa Z. Cameron, Lowell A. Miller

United States Department of Agriculture Wildlife Services: Staff Publications

Context. Contraception is increasingly used as a management technique to reduce fertility in wildlife populations; however, the feasibility of contraceptive formulations has been limited until recently because they have required multiple treatments to achieve prolonged infertility.

Aims. We tested the efficacy and evaluated potential side effects of two contraceptive formulations, a porcine zona pellucida (PZP) formulation, SpayVac^® and a gonadotrophin-releasing hormone (GnRH) formulation GonaCon-B™, in a population of free-roaming feral horses (Equus caballus). Both formulations were developed to provide several years of infertility with one injection.

Methods. Females were treated in June 2005 with …

Cliff Swallows, Swallow Bugs, And West Nile Virus: An Unlikely Transmission Mechanism, Paul T. Oesterle, Nicole M. Nemeth, Ginger Young, Nicole Mooers, Stacey Elmore, Richard Bowen, Paul Doherty, Jeffrey Hall, Robert Mclean, Larry Clark

United States Department of Agriculture Wildlife Services: Staff Publications

The cliff swallow (Petrochelidon pyrrhonota) could play an important role in the transmission of West Nile virus (WNV) because of its breeding ecology, reservoir competence status, and potentially high natural exposure rates. Cliff swallows nest within colonies and their nests are occupied year-round by swallow bugs (Oeciacus vicarius), hematophagus ectoparasites that feed primarily on cliff swallows. These parasites are likely exposed to WNV while feeding on infectious blood of nesting cliff swallow adults and nestlings and thus, if competent vectors, could contribute to seasonal elevations in WNV transmission. In addition, swallow bugs remain within nests year-round …

Habitat Succession, Hardwood Encroachment And Raccoons As Limiting Factors For Lower Keys Marsh Rabbits, Paige M. Schmidt, Robert A. Mccleery, Roel R. Lopez, Nova J. Silvy, Jason A. Schmidt

United States Department of Agriculture Wildlife Services: Staff Publications

The Lower Keys marsh rabbit (LKMR, Sylvilagus palustris hefneri), a marsh rabbit subspecies endemic to the Lower Keys, Florida was protected in 1990, however, populations continue to decline despite recovery efforts. We hypothesized on-going habitat loss and fragmentation due to succession and hardwood encroachment has led to increased edge, reduced habitat quality, and increased activity by native raccoons (Procyon lotor). These factors reduce the suitability of patches in a later successional state, thus threatening LKMR recovery and metapopulation persistence. We surveyed 150 LKMR patches in 2008, tallying adult and juvenile rabbit pellets, estimating measures of habitat succession …

Accounting For Individuals, Uncertainty, And Multiscale Clustering In Core Area Estimation, Ryan R. Wilson, Mevin B. Hooten, Bradley N. Strobel, John Shivik

United States Department of Agriculture Wildlife Services: Staff Publications

Core areas are important descriptors of animal space-use patterns, but current estimation methods rely on arbitrary rules and potentially lead to imprecise or erroneous area estimates. We proposed a Bayesian statistical model that incorporates an individual-based method for estimating core area boundaries. The model accounts for boundary uncertainty and multiple scales of clustering by partitioning a home range into ≥2 completely spatially random point patterns defined by a kernel density isopleth. We used data from coyotes (Canis latrans), bobcats (Lynx rufus), and red-shouldered hawks (Buteo lineatus) to estimate core areas for individual animals. We …

Assessment Of Abilities Of White-Tailed Deer To Jump Fences, Kurt C. Vercauteren, Timothy R. Vandeelen, Michael J. Lavelle, Wayne Hall

United States Department of Agriculture Wildlife Services: Staff Publications

There is a need for insight into fence heights required for impeding white-tailed deer (Odocoileus virginianus). We evaluated the ability of wild-caught deer to jump progressively taller fences and documented deterrence rates of 0% for fences ≤1.5 m followed by increasing deterrence rates of 14% at 1.8 m, 85% at 2.1 m, and 100% at 2.4 m. We documented 100% deterrence rates during 5 additional experiments with different deer and the test fence at 2.4 m, a common height of fences at captive deer facilities. Our results will be valuable to those managing spread of wildlife diseases, deer–vehicle …

Identifying Effective Attractants And Rodenticide Baits For Gambian Giant Pouched Rats, Gary W. Witmer, Nathan P. Snow, Rachael Piergross

United States Department of Agriculture Wildlife Services: Staff Publications

Following the escape of 8 Gambian giant pouched rats (Gambian rats) from an exotic pet breeder in 1999, Gambian rats became an established invasive species that persists in the wild on Grassy Key, Florida. Because of their large body size, the free-ranging Gambian rats pose a serious threat to native species and agricultural crops, especially if they find their way into mainland Florida. Initiated in 2005, the USDA Wildlife Services has been conducting an eradication and detection program in the Florida Keys. Today however, detecting, baiting, trapping, and removing the now sparse population of Gambian rats are proving difficult. Therefore, …

Fine-Scale Genetic And Social Structuring In A Central Appalachian White-Tailed Deer Herd, Brad F. Miller, Randy W. Deyoung, Tyler A. Campbell, Benjamin R. Laseter, W. Mark Ford, Karl V. Miller

United States Department of Agriculture Wildlife Services: Staff Publications

Spatial genetic structure in white-tailed deer (Odocoileus virginianus) has been examined at regional scales, but genetic markers with the resolution to detect fine-scale patterns have appeared only recently. We used a panel of microsatellite DNA markers, radiotelemetry data, and visual observations of marked deer to study fine-scale social and genetic structure in a high-density population of white-tailed deer (12–20 deer/km²). We collected genetic data on 229 adult females, 102 of which were assigned to 28 social groups. Our results were consistent with the conceptual model of white-tailed deer social structure, where philopatric females form social groups …

Host-Specificity Of Myxoma Virus: Pathogenesis Of South American And North American Strains Of Myxoma Virus In Two North American Lagomorph Species, L. Silvers, D. Barnard, F. Knowlton, B. Inglis, A. Labudovic, M.K. Holland, P.A. Janssens, B.H. Van Leeuwen, P.J. Kerr

United States Department of Agriculture Wildlife Services: Staff Publications

The pathogenesis of South American and North American myxoma viruses was examined in two species of North American lagomorphs, Sylvilagus nuttallii (mountain cottontail) and Sylvilagus audubonii (desert cottontail) both of which have been shown to have the potential to transmit the South American type of myxoma virus. Following infection with the South American strain (Lausanne, Lu), S. nuttallii developed both a local lesion and secondary lesions on the skin. They did not develop the classical myxomatosis seen in European rabbits (Oryctolagus cuniculus). The infection at the inoculation site did not resolve during the 20-day time course of the …