The concept of the Vertebrate Pest Conference originated in early 1960 from discussions among representatives of the University of California; the California Dept. of Fish & Game; the California Dept. of Agriculture; the California Dept. of Public Health; and the Branch of Predator and Rodent Control, Bureau of Sport Fisheries and Wildlife, U.S. Fish & Wildlife Service. The original participants recognized that few published documents on vertebrate pest control were available, as such information was typically contained within in-house reports of the various agencies that were largely unavailable and unable to be cited. Dr. Walter E. "Howdy" Howard of UC realized that having a conference would permit a Proceedings to be published, in which this information could be made widely available.
To plan such a conference, the organizing group, chaired by Dr. Howard, became the Vertebrate Pest Control Technical Committee, which arranged and hosted the first "Vertebrate Pest Control Conference" held in Sacramento on February 6 & 7, 1962. The planning committee formally became an incorporated non-profit entity in 1975, and the Vertebrate Pest Conference is now held in late winter or early spring every two years. It is the most widely-recognized conference of its kind worldwide.
Detailed histories of the development of this Conference are found in these publications:
Volume 23, 2008
During the past two decades, remarkable progress has been made in understanding the receptor events for detecting and processing information by the chemical senses (taste, smell and chemical irritation or chemesthesis) of vertebrates. This new information offers expanded opportunities to exploit the chemical senses of vertebrate pests to attract them, repel them, or otherwise modify their behavior in a manner that mitigates their potential to do damage. Here, I describe one example of each of these chemical senses. Irritants are attractive candidates for vertebrate repellents since they activate pain receptors, are innately avoided, and may be relatively non-toxic. Identification of specific irritant receptors and receptor cells has heightened interest in understanding sensory processing and species differences in this chemical sense. Molecular-cellular techniques with isolated cell-based systems can be used to screen for efficacy of irritants in previously uninvestigated species. These techniques can be both predictive and cost effective. Odors: Animals with certain diseases can be identified by an altered body odor. Next steps will include the identification of diagnostic odorants and a broader understanding of mechanisms of the odor message processing. Development of novel sensor devices using detectors such as DNA fragments, pheromone-binding proteins, and immobilized odor receptors may provide breakthroughs in our ability to detect and monitor disease vectors in the natural environment. Tastes: Animal species vary in their sensitivity to taste compounds, presumably as a consequence of ecological selective pressures. For example, cats, obligate carnivores, have no preferences for sweet carbohydrates due to an evolutionary change in a gene responsible for coding for the sweet receptor. Thus, the cat sweet receptor gene has been pseudogenized, presumably as a result of relaxed selection. A better understanding of the molecular biology of taste receptors in a species of interest, be it an endangered animal or a pest such as a pig or deer or coyote, should help in designing novel and effective repellents and attractants.
Outbreaks of E. coli O157:H7 associated with the consumption of leafy green produce from different regions within California have initiated a series of food safety management practices regarding wildlife access to the produce production environment and potential contamination of irrigation water supplies. Recent surveys of feral swine that document fecal shedding of E. coli O157:H7 underscore the potential for wildlife contamination of fresh produce under appropriate environmental conditions. Collectively, these observations have motivated retailers, processors, and growers of leafy green products to develop that set of ambitious guidelines regarding buffer zones, set-back distances, and fencing requirements for restricting wildlife access to the production environment. These issues and their ramifications for food safety and environmental quality will be discussed.
Efforts to exclude disease organisms from farms growing irrigated lettuce and leafy vegetables on California’s central coast are conflicting with traditionally accepted strategies to protect surface water and environmental quality. The agricultural community, scientists and producers, are caught between the requirements to safeguard water quality and efforts to ensure a safe food supply. These programs evolved independently, albeit side-by-side, leading to separate habits of thought among environmental and food safety scientists in academia, business, and non-profit programs. The potential for coordinated management of water quality and food safety on-farm management practices was the focus of a conference held in San Luis Obispo, California in April 2007. Conference presentations, discussions, farm visits, and working groups used existing technical guidance to frame research and organizational objectives. These conference products were summarized for inclusion in iterative on-line questionnaires, with conference attendees participating as respondents. This process, called a Delphi process, produced general research priorities in coordinated management. Conference participants, who self identified as having either food safety or water quality as their primary area of focus, prioritized research objectives under theme areas. There were general research objectives, which approached consensus by the whole group, including: 1) persistence and fate of pathogen in the crop and in conservation practices; 2) pathways by which pathogens move through the crop production system; and 3) identification of environmental conditions that promote pathogen survival and proliferation. Conference participants and Delphi respondents were not able to identify an existing forum for gathering and disseminating coordinated management information. Respondents placed their highest priority on the formation of a Coordinating Council, and identified those entities that ought to play specific roles within the Council. Two technical guidance documents, one emphasizing on-farm management of food safety and one stressing water quality practices, are already in use by a majority of leafy greens growers on California’s Central Coast. Used together, these technical guidance documents can be used to develop an initial framework for the evaluation and development of coordinated management practices that protect both human health and the environment. The conference final report and accompanying materials are published online at http://groups.ucanr.org/wqfsconf/.
The safety of the food supply is a primary consideration of farmers, wholesale and retail establishments, and ultimately consumers. In 2006, a major outbreak of food-borne illness in the U.S. caused by Escherichia coli O157:H7contaminated bagged spinach resulted in 3 deaths and over 200 illnesses. Studies have shown that cattle and some commensal wildlife are known sources of E. coli O157:H7, but limited investigations on small mammals and deer have shown minimal prevalence of this bacteria. In 2007, with oversight from the California Department of Food and Agriculture, produce industry representatives developed the Commodity Specific Food Safety Guidelines for the Lettuce and Leafy Greens Supply Chain, known as the Metrics. These have led to significant uses of rodent control techniques including baits, traps, buffer strips and vegetation clearing in areas around leafy green production. One of the major issues regarding these strategies is that the target rodent species is generally unknown. Growers are faced with complying with buyers’ interpretations of the Metrics or losing the sale of their crop. Until we provide better information on the occurrence and type of rodents in and around leafy green crops and food safety, we will have limited ability to help growers use cost-effective and environmentally acceptable methods to protect crops from potential rodent contamination. Rodent control experts need to provide specific strategies to help growers with the important issue of rodents and their association with crops and food safety.
Issues of food safety related to wildlife are discussed from a growers’ perspective. We describe how the “Metrics” are implemented, from an agricultural producer’s perspective, and how buyers’ decisions influence field practices related to wildlife management. Growers are working together within the current requirements, so that agricultural producers can continue to market products while remaining committed to environmental stewardship and conservation, and to high standards of food safety.
Feral swine may harbor the causative agents of important foodborne diseases such as brucellosis, cryptosporidiosis, salmonellosis, and trichinosis. We described recently the isolation of Escherichia coli O157:H7 from feral swine in the central California coast during an investigation of a nationwide outbreak associated with consumption of contaminated fresh baby spinach. Additionally, the foodborne pathogen Campylobacter was found in tissues and feces from the same population of feral swine. Feral swine are the most abundant free-roaming ungulate in the United States, and their range in California continues to expand, with the highest numbers reported on the central coast. The expansion of feral swine in mainland California and concomitant damage to agriculture and public health underscore the need for mitigation strategies. A number of lethal and non-lethal methods for feral swine management have been described, including hunting, depredation, trapping, and exclusion such as fencing. This paper reviews current concerns relating to food safety and feral swine. The advantages and potential pitfalls of mitigation strategies to reduce the risk of contamination of raw vegetable commodities by free-roaming feral swine are discussed.
Large numbers of ring-billed gulls, herring gulls, and greater black-backed gulls roost each night on a municipal drinking water source in Maine and have been identified as the primary source of elevated fecal coliform bacteria levels. The lake has a resident gull population of approximately 800, while more than 3,000 gulls have been observed during seasonal migration. To alleviate this public health concern, the U.S. Department of Agriculture APHIS Wildlife Services program implemented an Integrated Wildlife Damage Management program in 2005. The program included the use of pyrotechnics and watercraft to harass gulls, as well as shooting to reinforce and enhance the effectiveness of non-lethal methods. Management activities were effective in keeping gulls off the drinking water source and lowering coliform bacteria levels to within EPA water quality standards. Additionally, the integrated program also involves an ongoing survey in areas surrounding the lake to identify feeding, loafing, and roosting areas that may affect gull movement. Information collected from the survey will result in more effective management practices and contribute to the long-term goal of reducing gull use on the lake.
Routes that cattle become exposed to and contaminated with Escherichia coli O157 remain enigmatic. To ascertain the potential role of wild birds, particularly European starlings, in the transmission of Escherichia coli O157:H7 among dairy farms, the ecology of this pathogen in these birds was studied. Bird movement from roost sites to farms was monitored using radio-telemetry (n = 49). Concurrently, frequency of livestock feed contamination and E. coli O157:H7 carriage in birds and in cattle was ascertained. Most of the birds tagged from farms in the limited geographic region roosted communally at a location within 20 km of the farms where they were tagged. Individual birds returned frequently to the same farm on a daily basis for feeding. E. coli O157:H7 was cultured from approximately 3% of starlings and 4% of cattle in the study population. We have previously reported the isolation of indistinguishable molecular subtypes of E. coli O157 from starlings from different farms. Clearly, European starlings can serve as a vehicle to disseminate this pathogen from farm to farm. What remains to be determined is the magnitude of the contribution that birds have in the overall ecology of E. coli O157 in livestock populations, and how this might be mitigated.
Commensal rats cause significant damage to human food supplies and property around the world. They also cause severe ecosystem disruption, and even species endangerment, when introduced to islands. Effective attractants could help manage rat populations by increasing the probability of getting rats to detection stations, traps, and bait stations. Bait stations may contain a rodenticide, a fertility control agent, a disease vaccine, or an ecto-parasite control chemical. Effective rat attractants have not been made commercially available, although a few candidates have been identified over the years. We investigated 18 commerciallyavailable materials for their attractiveness to groups of wild Norway rats in a pen study. The most promising candidate attractants, based on the number of station visits, were almond, ginger, and lemon extracts. However, a subsequent, brief field trial at a livestock feedlot with a resident Norway rat population did not result in greater rat capture numbers with any of the 3 attractants over traps only containing water. It appears that additional testing of these and other materials will be necessary before an effective attractant can be discovered and made available for Norway rat population management.
Many rodent species, including both commensal and native species, cause numerous types and extensive amounts of damage worldwide. Much of their adverse effects on human populations involve food consumption and contamination as well as disease transmission. Their digging and gnawing abilities, however, are well developed and other types of damage result. These include the undermining of hydraulic structures, ditches, levees, building foundations, roads, and runways. They also damage pipes, cables, and building insulation, occasionally resulting in power outages and fires. Effective and efficient barriers would help reduce these latter types of rodent damage. We examined two types of geo-textile (containing metal fibers and called “Xcluder”) materials for their ability to prevent house mouse and Norway rat entry through regularly-used openings. We also examined the materials ability to protect highly palatable food sources from these rodents. Although these were preliminary trials, the materials showed considerable promise in some applications. We discuss potential applications and ways to maximize the effectiveness of geo-textile barriers, along with additional research needs.
Management for beaver now ranges from lethal removal of nuisance individuals to reintroduction of individuals for wetland restoration and to increase wildlife and habitat diversity. Management, or lack thereof, is driven largely by stakeholder concerns at the local and regional level. In many cases with management of beaver and other species, there are unclear visions of how wildlife populations may exploit resources after successful restoration or with changing landscape conditions (e.g., habitat quality and competition). With increasing conversion of the modern-day landscape, natural resource managers must make pragmatic decisions on the potential effects habitat alteration has on system stability. In 2000, the United States Army Corps of Engineers received approval from Congress to construct the Tres Rios Ecosystem Restoration and Flood Control Project in Phoenix, Arizona. Upon completion, this multi-phased, 7-mile (11.3-km), 1,500-acre (607-ha) project is designed to include a 4.25-mile (6.8-km) flood protection levee, an effluent pump station, and development/maintenance of emergent wetlands, riparian corridors, and open water marshes to replace existing non-native saltcedar. In 2000, Tres Rios constructed a demonstration area onsite that used reclaimed wastewater from the 91st Avenue Treatment Plant to establish wetland habitat. Simultaneously, we began the Tres Rios Beaver Research Project to determine the possible effects beaver have on riparian and wetland habitats. Studies within this project found that existing non-lethal management techniques were generally ineffective; however, topical application of fructose and polyethylene glycol showed promise as a technique to increase palatability of invasive Tamarisk spp., while palatability of native tree species could be reduced by application of an herbivore repellent. Other studies developed new techniques for anesthetizing beaver and increasing radio transmitter retention time on beaver. Through monitoring movement of beaver and using landscape genetic techniques to explore population diversity, researchers found deviations from published literature on beaver, suggesting that density-dependent factors may be driving beaver behavior and movement in this environment. We describe the planning process involved in developing these research studies to address stakeholder concerns.
An Analysis of the Efficacy and Comparative Costs of Using Flow Devices to Resolve Conflicts with North American Beavers Along Roadways in the Coastal Plain of Virginia
Road damage caused by beavers is a costly problem for transportation departments in the U.S. Population control and dam destruction are the most widely used methods to reduce road damage caused by beavers, but the benefits of such measures in some situations are often very short-term. At chronic damage sites, it may be more effective and cost-beneficial to use flow devices to protect road structures and critical areas adjacent to roads. To determine the potential benefits of using flow devices at chronic beaver damage sites, from June 2004 to March 2006 we installed 40 flow devices at 21 sites identified by transportation department personnel as chronic damage sites in Virginia’s Coastal Plain. Following installations, study sites were monitored to determine flow device performance and any required maintenance and repairs. Between March 2006 and August 2007, transportation department personnel were surveyed to collect data on flow device efficacy and comparative costs. As of August 2007, transportation department personnel indicated that 39 of the 40 flow devices installed were functioning properly and meeting management objectives. The costs to install and maintain flow devices were significantly lower than preventative road maintenance, damage repairs, and/or population control costs at these sites prior to flow device installations. Prior to flow device installations, the transportation department saved $0.39 for every $1.00 spent per year on preventative maintenance, road repairs, and beaver population control. Following flow device installations, the transportation department saved $8.37 for every $1.00 spent to install, monitor, and maintain flow devices. Given the demonstrated low costs to build and maintain flow devices, transportation agencies may substantially reduce road maintenance costs by installing and maintaining flow devices at chronic beaver damage sites.
Groundhogs cause extensive damage to crops, landscaping, and structures throughout their range. However, control methods can be objectionable to the public. Concussion blasting equipment provides an alternative to historic groundhog control (i.e., live-capture and lethal traps, asphyxiation, poison, and firearms) in suburban and rural settings. Prior to use in our market, we tested the efficacy of the VARMITgetter device during 3 trials in September 2006. Trials were performed to determine the amount of gas (oxygen and propane mix) and length of injection time needed to provide a quick and consistent kill at minimum cost including labor, materials spent, and wear-and-tear. After detonation, dens were excavated to verify the effectiveness of the concussion blast method. During subsequent market testing, calibrations were adjusted to account for soil type, soil compaction, age of the burrow system, number of burrow entrances, and ground moisture. Testing to date has proven this method to be a viable alternative over other methods. Unique advantages of concussion blasting equipment include: one site visit; rapid kill; no equipment left behind; increased safety to pets, livestock, and people; and increased employee productivity.
California ground squirrels are known to inhabit different landscapes and terrains. Farms and ranches with ground squirrels are often at an advantage over other types of locations such as schools and public parks, where squirrel control options are more limited. Many private companies and public agencies dealing with squirrel problems experience public opposition to the use of poisons in public areas and must find other workable solutions. Live-trapping California ground squirrels is one control method that is being considered by many agencies. City and county parks, public and private schools, horse boarding stables, and organic farms are some of the locations appropriate for use in this type of program. The use of live-traps for safety and target-specific reasons, and the use of CO2 as the most humane method of euthanasia for rodents, are widely accepted by most people, even when the trapping is done openly in public. Live trapped ground squirrels can have a benefit beyond the reduction of squirrel damage. Using trapped squirrels as a natural food source for hawks, owls, and eagles at raptor rehabilitation facilities makes this approach an effective, safe, and acceptable control method in specific places.
Nutria are large semi-aquatic, herbivorous rodents native to South America, but were brought to the United States in the early 1900s for the fur farming industry. At high densities, nutria damage marsh vegetation. To more effectively manage nutria, we identified effective attractants and designed a multiple capture trap (MCT). Four lures (nutria urine, nutria fur extract, synthetic anal gland secretion, and a commercially available apple-based lure) were examined under field conditions, using leg-hold traps. A total of 285 nutria were captured during a 10-day trial with 1,000 trap-nights. All lures tested increased trapping success from 42% to 120% over untreated traps, with nutria fur extract being the most effective. Additionally, the lures did not attract nontarget animals. Next, we tested the MCT: 6 were baited with foods (carrots, corn, and sweet potatoes), and another 6 used trays of fertilized marsh plants as the lure. During the 10-day trial, with 122 trap-nights, 10 nutria were caught in the food-baited traps and 12 in the marsh plant-baited traps. As many as 3 nutria were captured overnight in one trap. On two occasions, individual nutria escaped the traps when approached by a person. No non-target animals were captured, however, it was suspected that swamp rabbits were entering the MCTs to feed and then were able to go back out the “one-way door”.
Rangeland owners and managers control populations of black-tailed prairie dogs for many reasons, but chiefly to preserve rangeland value for raising livestock. Several control options are available, but toxic baits are likely to offer the most economical and effective control. Baits are currently available with zinc phosphide and anticoagulant active ingredients, which have different chemical and toxicological characteristics. Field trials indicate that users may experience variations in the efficacy of the different baits, and further investigation is needed to identify the factors that influence these variations.
New York State has an estimated population of 249,702 resident Canada geese. Human-goose conflicts are increasing, including unacceptable accumulation of goose feces in public parks, overgrazing of landscaped lawns, noise, and aggressive behavior of individual geese. An integrated Canada goose management program was conducted and evaluated at 8 sites in Orange County, New York from 2004 to 2006. The program, conducted from March through November each year, consisted of egg oiling (300-470 eggs oiled a year), hazing to reduce local goose populations using multiple techniques, public outreach/education, and program monitoring. The monitoring component included goose movement and population surveys using neck-collared geese and standardized fecal counts, at both managed and unmanaged sites. We monitored 3 unmanaged (“control”) sites to provide a comparison. We conducted fecal surveys, as an indirect method for potentially estimating site-specific goose populations and associated reduction in damage. The number of droppings counted, when standardized to droppings per foot per day, decreased at treated sites (2004, 0.16; 2005, 0.12; 2006, 0.05) but did not differ at unmanaged sites, indicating a sustained population reduction on site during the project. In addition, the mean number of geese observed at treated sites decreased each year (2004, 77; 2005, 19; 2006, 11) while the mean number at unmanaged sites did not differ. The alternate location of the majority of dispersed geese is unknown, although monitoring of marked birds indicates that many birds moved only short distances (<2 km). The implementation of an integrated non-lethal goose damage management program over 3 years reduced the number of Canada geese at specific locations and minimized local conflicts. The widespread adoption of this type of program could reduce humanCanada goose conflicts across a larger landscape but will require extensive coordination of local projects, a public involvement process, and an intensive, long-term commitment of resources.
Successful Use of Alarm and Alert Calls to Reduce Emerging Crop Damage by Resident Canada Geese near Horicon Marsh, Wisconsin
Increased populations of resident Canada geese create major crop loss problems for farmers, especially in areas that become traditional sites for brood-rearing. Such sites concentrate geese and goslings in locations where food is abundant and flightless adults and young find escape safety on adjacent lakes or rivers. Emerging corn, winter wheat, and soybeans are favorite foods, and these sustain extensive crop damage when near water and brood-rearing sites. From 16 May to 28 August 2007, alarm and alert call playbacks from GooseBuster call units were used with and without other scare reinforcement to assess efficacy of different methods at reducing crop damage at multiple sites near Horicon Marsh, Wisconsin. Test sites were recommended by USDA APHIS Wildlife Services personnel as being sites with heaviest early summer crop damage reported in prior years. Criteria for success were based upon geese/hours/month or geese/hours/week of field use before and after treatment, using frequent counts of geese on properties, weekly farmer interviews, and dropping counts in fields to estimate number and number of hours geese were present. Crop damage assessment by USDA compared current year to prior years’ assessment, or used visible signs of damage and extent. On-demand use of call units, coupled with firing screamer and banger shells, was found to be the most effective method for inducing long-term crop avoidance. Crop damage reduction was very successful, ranging from a 94.3% reduction at one site (17 bushels lost in 2007 versus 297 bushels in 2006), to several fields declared to have “no significant goose damage in 2007” by USDA crop evaluation personnel. Goose hours/month on the largest field data collection decreased from >36,000 to <200 geese/hour/month, a 99.45% reduction. No sign of habituation to reinforced “on-demand” alarm call use was found over the course of the 100 days of the study.
The use of real and artificial effigies has proven to be an effective alternative to pyrotechnics and other traditional methods for the dispersal of nuisance vulture roosts. During the winters of 2005-2006 and 2006-2007, we applied the same principles of effigy use to a large urban crow roost in the Lancaster, PA area. The initial deployment of effigies occurred in November 2005 in a wooded area where approximately 10,000 birds had already congregated to the detriment of nearby businesses. By December, as the roost grew to approximately 40,000 birds, we successively moved the birds to a series of alternate sites along a wooded creek. In January, the crows split into smaller roosting aggregations and began to disperse. In October 2006, before wintering crows arrived, we installed effigies in wooded areas where the crows had settled the previous year. Although preferred roost habitat in 2005-2006, these areas were used only sparingly by crows throughout the second winter. Instead, crow roosting activity was focused in downtown Lancaster. At wooded sites where 5,000-10,000 birds did settle, we installed additional effigies and the birds responded by leaving. During November-December 2007, we provided technical assistance to a citizen-based crow management effort that successfully incorporated the use of artificial crow effigies with other harassment to move the roost (30,000 to 40,000 birds) to a site acceptable to the community. We conclude that crow effigies (carcasses, taxidermic mounts, or artificial models) are useful components of roost dispersal efforts and can possibly be used in other applications, such as crop damage management.
American crow populations have increased steadily since 1966 in many parts of the U.S. Large winter congregations of crows in urban environments have resulted in an increased number of requests for assistance in managing nocturnal roosts in New York. In 2002, the USDA APHIS Wildlife Services program initiated a large-scale non-lethal winter roost dispersal program in Troy, New York. Since that time, similar programs have been implemented in 4 other cities in New York to manage crow roosts ranging in size from 8,000 - 63,000 individuals. The goals of the programs were to minimize noise, accumulations of crow feces around residences, strong odors associated with droppings, property damage, clean-up costs, and potential threats to human health and safety. The primary management strategy relied on dispersing concentrated crow populations from high-impact high-conflict areas, to low-impact low-conflict areas. An integrated management program using pyrotechnics, amplified recorded crow distress calls, and hand-held lasers was implemented to successfully disperse local crow roosts, reducing populations at the majority of core roost sites each year by more than 98%. In some instances, significant reductions in crow numbers and associated damage persisted >8 weeks after management without additional interventions, although most sites required multiple additional “spot treatments.” High-profile urban wildlife management projects of this type require multiple meetings with key stakeholders and the public and often attract intense media interest, adding complexity to these programs. We provide summary information from 5 cities in New York documenting crow management techniques, intensity of effort, number of interventions required to relocate crow populations, and key lessons learned regarding sciencebased project documentation, project transparency, communication, and the need for long-term adaptive management strategies to meet project goals.
Raven populations that depredate livestock, damage agricultural crops, and injure endangered and threatened species, can be managed with egg baits containing the avicide DRC-1339 (3-chloro-p-toluidine). Estimating baiting efficacy is difficult, as DRC-1339 is a slow-acting toxicant. Efficacy estimation is further complicated by the feeding behavior of ravens at bait sites. To evaluate the efficacy of an egg baiting operation, we developed a computer simulation to predict bait consumption by ravens, incorporating a DRC-1339 degradation module to predict DRC-1339 bait concentration at the time of consumption and an effects module to predict the mortality associated with the resulting DRC-1339 dose. Details of the simulation will be presented in the context of predicting baiting efficacy using egg baits in different climatic environments. These preliminary results provide the basis for designing field studies that can be used to improve and validate the model.
Double-crested cormorants commonly depredate channel catfish at aquaculture facilities in the southeastern U.S., causing significant economic loss. Prior research has demonstrated regional night-roost harassment (i.e., “major pushes”) to be an effective technique to temporarily reduce cormorant use on aquaculture ponds; however, these efforts were extremely labor intensive and changes in impacts were difficult to quantify. We conducted a preliminary study to investigate the efficacy of site-specific, night-roost dispersal (n = 6) using lethal control on cormorant abundance by monitoring the number of birds at randomly selected aquaculture facilities for 3 days prior to and following night-roost dispersals. The effect of dispersal varied greatly by study site. At one site, the mean abundance of cormorants on catfish production ponds decreased following dispersal; however, on the other 5 sites the mean abundance of cormorants did not change on catfish production ponds following night-roost dispersal. We recommend further research to evaluate the effectiveness of night-roost dispersal using lethal control. Furthermore, we offer recommendations for the design of future large-scale studies, which include improvements to reduce large variation.
Methodology to Quantify the Economic Impact of the Double-Crested Cormorant (Phalacrocorax auritus) to the Oneida Lake Region, New York
The economic impact of wildlife-caused damage and associated management is one of the many factors that arguably play a role in the decision-making process of wildlife managers. Often the role of an economist is to value the damage created by wildlife, or to assess programmatic efficiency to determine if changes can be made to increase return per dollar invested in management efforts. Frequently, the results of economic analyses of wildlife-caused damage are used to justify program efforts in the pursuit or maintenance of funding. The complexity of determining the economic impact of wildlife-caused damage requires that there is a clear understanding of the methodological approach used to determine impacts. Examining specific methodological approaches used in actual case studies provides a systematic replicable approach to valuing damage. This study outlines the methodology for determining the economic impact of cormorant damage to natural resources in a local economy: the Oneida Lake Region of central New York.
Israel-Ukraine Cooperation for Experimental Management of a Shared Overabundant Population of Great Cormorants (Phalacrocorax carbo)
Since the mid-1980s, there has been a steady rise in the numbers of great cormorants in all Eurasia, and in the number over-wintering annually in Israel. Winter counts in recent years show about 15,000 - 20,000 great cormorants in Israel; they arrive in October and stay until March. Over the years, colonies of over-wintering great cormorants, which can have over 5,000 individuals each, come into conflict at commercial fish farms in Israel, which are in the form of local concentrations of open earthen ponds, in which are grown very high concentrations of food fish, mainly carp, tilapia, grass carp, and mullet. Over the years, many attempts have been made to reduce the negative impact of over-wintering great cormorants on the commercial fish farms in Israel, utilizing lethal and non-lethal methods. Over 50 banding returns from the last 2 decades showed that the great cormorants over-wintering in Israel originated in the area around the northern Black Sea and Sea of Azov, around the Crimean Peninsula in southern Ukraine (about 1400 km or 850 miles due north). This overabundant species causes considerable damage around its nesting sites in Ukraine by interfering with endangered waterbirds, and by conflicting with fishermen. Israel has recently been exploring ways to utilize international cooperation for management of the nesting population in Ukraine, in order to reduce the size of the wintering population in Israel and also to prevent damage to endangered waterbirds in Ukraine. The major instruments are the European Union’s project INTERCAFE (Interdisciplinary Initiative to Reduce Pan-European Cormorant-Fisheries Conflicts: www.intercafeproject.net), and the African-Eurasian Waterbird Agreement (AEWA) under UNEP’s Convention on Migratory Species (CMS): www.unep-aewa.org, as well as other International Environmental Agreements. An experimental program is proposed for reducing the nesting success of the Ukrainian population. A smaller great cormorant population should impact less upon nesting waterbirds in Ukraine and also decrease the intensity of the conflict with both Ukrainian and Israeli fishermen, thereby lessening the extent of lethal control used against great cormorants in both countries. The proposed experimental program includes egg-oiling of ground-nesting birds and hazing tree-nesting birds with green lasers.
Seasonal Occurrence of Blackbird Species (Icteridae) in Wild Rice (Zizania): A Response to Rice Stage or Breeding Phenology?
Blackbird species (Icteridae) are considered a primary cause of yield loss prior to harvest in wild rice, which equaled about $3 million in 2007. Although rice consumption should be a null model of bird damage to yield, data from cage traps and point counts indicate that blackbird flocks arrive in wild rice fields 3 to 4 weeks before rice was available for consumption, but coincidental with the time when blackbird form post-breeding flocks. Wild rice plants appear to be attractive habitat from the time the wild rice begins heading until it is harvested (c. 6 weeks), even though wild rice is a food source only for the last 2 to 3 weeks (milk stage to harvest of mature grains). The onset of occurrence in wild rice fields appears to be a function of breeding season of red-winged blackbird and Brewer’s blackbird, specifically they arrive shortly after the time when young-of-the-year become independent of parental care (first week of July). Hence, nesting phenology is the best predictor of blackbird occurrence and their potential damage to wild rice.
The Compound DRC-1339 Concentrate – Staging-Areas label is approved in North Dakota for use in non-crop staging areas near blackbird roosts. Potential blackbird damage affects sunflower planting patterns and reduces profits. One option to manage damage is to reduce the local blackbird population using DRC-1339 bait. The challenges are to limit nontarget bird hazards while attracting large numbers of blackbirds. During fall 2007, we assessed the nontarget bird risks of using rice baits on elevated bait trays attached to the top of decoy traps. During random visits to bait sites, we recorded 968 individual birds and 12 avian species. Blackbirds accounted for 95% of all tray visits. Sparrow species were the most prevalent of the non-blackbirds. Strategic placement of the bait trays near large roosts will be necessary for this technique to be successful. Ultimately, Wildlife Services might use DRC-1339-treated rice baits on bait trays for managing local blackbird damage.
Breeding Red-Winged Blackbird Response to Conspecific Models Placed in Pre-Copulatory Position: Implications for Reproductive Control
Sunflower producers in the northern Great Plains are annually plagued by feeding flocks of blackbirds, especially red-winged blackbirds (RWBL). Past techniques aimed at reducing blackbird damage have had varying degrees of success, but the estimated annual loss of sunflower remains at ≥$10 million. Thus, there is a need for new innovative approaches to managing blackbird damage. One approach is to find non-lethal species-specific methods of lowering reproduction by discovering vulnerable behavioral tendencies in the reproductive cycle of RWBL. Male RWBL are a good candidate for reproductive control because of their territorial and polygynous reproductive behavior. We have designed a study to assess the male RWBL response to a model placed in pre-copulatory position under different treatment scenarios. Our objective is to discover the conditions under which we can attract the largest numbers of males to the model, keeping in mind that these models could potentially be used as a delivery system for a reproductive inhibitor. While we had nearly no response from territorial males, we found that floater males (those that do not hold territories) readily copulate with conspecific models. Floater intrusion and copulation occurs more often in the early part of the breeding season and while females were most fertile. Of the floater males that attempted to copulate with a model, 96% were SY (second-year) males; SY males are considered “non-breeding”. Preliminary results show that reproductive management would be most successful in the floater male population. Since the majority of floaters are SY males, it is likely that they will attain territories in future breeding seasons. This would require the use of a long-term sterilant. This method has the potential to target specific breeding populations, but more research is needed on movement patterns of floater males.
Assessing Bird-Aircraft Strike Hazard (BASH) Risk Associated with Breeding and Migrating Osprey (Abstract only)
The osprey (Pandion haliaetus) is one of the most widely distributed and well studied bird species of the Northern Hemisphere; however, little is known about their potential impacts to military flight operations. A Department of Defense Legacy Natural Resources Program-funded multi-agency research project examining the strike-risk posed by breeding and migrating osprey was initiated in 2006. During the 2006 nesting season, 6 adult osprey were live-captured, fitted with GPS-capable satellite transmitters, and released from selected nest locations near Langley Air Force Base, Virginia, in the Mid-Atlantic Chesapeake Bay Region. We monitored satellite-tagged osprey movement patterns of fitted osprey by tracking them during the breeding, migration, and wintering periods via the ARGOS satellite network. Movement information collected from breeding osprey was cross- referenced to Langley Air Force Base flying operations to assess the risk breeding osprey pose to military aircraft near the airfield. In addition, migratory patterns of osprey were evaluated to assess the risk migrating osprey to military aircraft operations along the Eastern seaboard. Incorporation and integration of osprey movement information (e.g., timing, travel routes) into military flight mission planning systems will increase pilot awareness of potential osprey-aircraft strikes during critical time periods and will allow for military flight operations to occur at times and locations that minimize the risk of osprey-aircraft collisions.
Relative Risks of Predation on Livestock Posed by Individual Wolves, Black Bears, Mountain Lions, and Coyotes in Idaho
Gray wolf populations have exceeded anticipated recovery levels since they were first reintroduced to central Idaho in 1995. Although wolf predation on livestock is a relatively minor issue to the livestock industry as a whole, it can be a serious problem for some individual livestock producers who graze their stock in occupied wolf habitat. This paper compares Idaho population estimates for gray wolves with the available information on numbers of livestock killed by wolves in order to estimate numbers of livestock killed per wolf. This information is compared with similar analyses for other species most commonly implicated as predators of livestock in Idaho (coyotes, black bears, and mountain lions). Population estimates for coyotes, black bears, and mountain lions are based on review of available scientific literature and analyses in environmental assessments prepared by Wildlife Services, as well as estimates from the Idaho Department of Fish and Game. Wolf population estimates are based primarily on monitoring information provided by the Idaho Department of Fish and Game and the Nez Perce Tribe. Estimates of numbers of livestock killed by wolves, coyotes, black bears, and mountain lions are based on survey data compiled by the National Agricultural Statistics Service. Rationale for use of various data sets is provided, and limitations of the data are discussed. This analysis suggests that individual wolves are much more likely to prey on livestock than are individuals of any other predator species in Idaho.
Conflicts between urban coyotes and humans have increased in recent years, particularly in the West. These include aggression and attacks on children, adults, and on pets; and damage to drip irrigation systems, garden crops, and other resources. News reports and our contact with agencies have informed us of more than 110 incidents in California alone, most within the past decade, in which humans were bitten by coyotes. However, few data are available on incidents of pet loss or other human-coyote conflicts in urban habitats. We suspect many conflicts occur because of human behaviors that results in coyote habituation; we hypothesize that with informed management, most are preventable. We have developed a web site, http://www.CoyoteBytes.org, as a tool to provide science-based management recommendations to homeowners and municipal officials to reduce coyote conflicts in urban / suburban areas. In addition to providing information, the website allows individuals to voluntarily upload photos and video of urban coyotes, and to submit first-hand reports describing conflicts and encounters. The web site contains an incident map, an Internet-enabled Geographic Information Systems (webGIS) tool, allowing coyote incidents to be displayed via a dynamic mapping interface by type of incident and by progress through time. The website became functional in September 2007 and is being pilot-tested in San Diego, Orange, and Los Angeles counties, California. The information being collected concerning coyote encounters and incidents should, over time, provide a means for a more complete analysis of this problem, thereby improving our management recommendations. A better factual understanding of the dimensions of the problem, as well as impacts of various management strategies currently in use, should help reduce some of the polarized atmosphere surrounding cities’ and counties’ attempts to find appropriate solutions to these conflicts.
Live Trapping and Monitoring Mountain Lion Movements within a Feral Horse Population in Storey County, Nevada, 2005 - 2007
The depredation of feral horses by mountain lions is usually a rare phenomenon and only a few cases have been documented in scientific literature. While such reports indicate that mountain lions are easily capable of killing feral horses, these studies have focused solely on the feral horses and have neglected to consider the mountain lion’s perspective (i.e., movement patterns, prey choice). Today, feral horses have created an artificial prey base for mountain lions, and even if natural ungulate species were not present, mountain lions appear to survive and flourish while consuming feral horses. During a feral horse behavior study conducted in 2005, a resident mountain lion in the Virginia Mountain Range was deemed responsible for several feral horse deaths, with most of the carcasses found being young foals or juvenile horses. A large live trap was developed and was strategically placed in a mountain lion travel corridor where the depredated horse carcasses were found. Bait in the live trap was changed on a weekly basis to prevent spoilage. The trap was set from October through December 2006 and monitored each morning. A 7-yearold, 60-kg female lion was caught in the trap after 3 months of trapping efforts. It was tranquilized, weighed and measured, and fitted with a satellite GPS collar. The satellite collar gave 4 locations per night. Based on the those GPS locations, we determined the lion had depredated on many feral horses, and it continued to range in the same area, even though other native wildlife species, such as mule deer, were in low densities. We monitored her progress until October 2007 to determine overall movement patterns and prey choice.
Dingo Control or Conservation? Attitudes Towards Urban Dingoes (Canis lupus dingo) as an Aid to Dingo Management
There is surprisingly little research into urban dingoes, even though urban areas in Australia are rapidly increasing, along with a concurrent increase in the number of reported conflicts with wildlife. Misguided and so-called ad hoc management of dingo populations, often caused by an over-reaction by the media to a situation, is commonly accredited for these conflicts. There can also be confusion over whom to contact when problems arise. A survey of the attitudes of parents of school-aged children towards urban dingoes in their area was carried out in Maroochy Shire, in South-East Queensland. Respondents generally believed that dingoes could be dangerous, but they preferred that control methods used be ‘humane’. Most respondents obtained their knowledge of dingoes from television and news media; about ¾ of respondents requested information regarding dingo management issues. The Queensland Parks and Wildlife Service was selected by a majority of respondents as the preferred agency to deal with dingo management.
Considerable effort has been put into retaining older vertebrate pesticides and improving the effectiveness and safety of pest control. Nevertheless, conventional control targeting single species is sometimes still associated with non-target impacts, bioaccumulation of toxins, fluctuating pest numbers, and unexpected ecological consequences. To counter this, we are developing multi-species bait types for sustained field use that are more palatable to vertebrate pest species. We are incorporating “low-residue” toxicants, namely zinc phosphide, cholecalciferol, diphacinone, and a combination of coumatetralyl and cholecalciferol, in new bait formulations. Looking to the future, we seek to increasingly combine “low-residue” characteristics with humaneness. New humane formulations of cyanide are being developed for a variety of pest species, and para-aminopropiophenone is being introduced for predator control in New Zealand as part of the product development and registration pipeline.
Concerns Regarding Proposed Restrictions in the Use of Second-Generation Anticoagulant Rodenticides for Commensal Rodent Control
The development of second-generation anticoagulant rodenticides for commensal rodent control arose from the need to overcome genetic resistance to earlier anticoagulants, to improve efficacy, and to reduce hazard over older acute rodenticide materials. Over the past three decades, the second-generation anticoagulant products have become the principal commensal rodenticides used in the U.S. and elsewhere. During this long usage, individual cases of human and nontarget wildlife exposure have been documented, and the significance has been debated. Following a lengthy re-registration and review process, the U.S. Environmental Protection Agency in January 2007 proposed restrictions on the use of second-generation anticoagulant rodenticides for commensal rodent control. The proposed restrictions would shift emphasis to other rodenticides, including those with inherent problems that were the basis for developing second-generation anticoagulants. Reduced efficacy, prolonged public exposure to rodents, limitations in bait formulations and placements, increased genetic resistance, and greater application rates (exposure) are anticipated if these restrictions are adopted. Various nontarget concerns will remain with alternative products and use patterns by professional users and consumers, including use of products without specific antidotes. These impacts would occur amidst increasing rodent problems in many U.S. municipalities with declining management resources and aging infrastructure. Alternative measures should include use of human taste deterrents in baits and revised label statements to limit the use of all commensal rodenticide from sensitive areas, including placement along fence lines, and bordering natural habitats.
Concerned that San Joaquin kit foxes from urban areas may be exposed to commensal anticoagulants, the California Department of Fish and Game, Pesticide Investigations Unit, in conjunction with the Endangered Species Recovery Program’s Urban Kit Fox Project, began monitoring San Joaquin kit foxes from the Bakersfield, CA population. Necropsies were performed and liver tissue samples collected from kit fox carcasses. Livers from archived kit foxes dating back to 1977 were also analyzed. A non-urban population of San Joaquin kit foxes from Lokern was used as a control. Other predators in the area, including coyotes and red foxes, were also analyzed for comparison. Between 1999 and 2007, tissue samples from 45 animals have been analyzed for residues of anticoagulant rodenticides. Anticoagulant compounds identified included brodifacoum, bromadiolone, pival, and chlorophacinone. Twenty-six of the 30 San Joaquin kit foxes from Bakersfield contained at least one anticoagulant, and the most commonly detected anticoagulant was brodifacoum. None of the 12 Lokern San Joaquin kit foxes contained anticoagulants. Other predators followed the same pattern: both red foxes from Bakersfield contained anticoagulant residues, but the coyote taken from Lokern did not.
Benzoate Adjuvant to Increase the Utility of Methylxanthine Pesticides: Identification of a Potential Rodenticide Formulation for Organic Food Production
There is growing interest in the use of natural products such as caffeine and theobromine for control of a variety of pest species. We hypothesized that the limited water solubility of these compounds limits their effectiveness. To overcome this hurdle, we evaluated the use of sodium benzoate as an adjuvant to increase the solubility and potency of methylxanthines. Our results indicated that sodium benzoate increased the toxicity of a methylxanthine mixture to rodents but not to canids. These results indicate that sodium benzoate has potential for increasing the efficacy and selectivity of methylxanthine-based rodenticides. As methylxanthines and sodium benzoate are plant-derived natural products, potential applications for methylxanthine and sodium benzoate based pesticides include organic food production.
Many fish stocks targeted by fishermen are also a primary food source of marine mammals. Normally this would be viewed as competition for a common resource. With the passage of the Marine Mammal Protection Act (MMPA) in 1972, marine mammals are protected which has aided in the recovery of numerous species. Along the West Coast, the MMPA has been highly successful in the recovery of most stocks of California sea lions and Pacific harbor seals, and it has resulted in more frequent interactions with commercial and recreational fishermen, causing damage to fishing gear and loss of catch. Non-lethal methods to eliminate or reduce pinniped predation have been unsuccessful. This paper summarizes the issue of marine mammal depredation in general, examines some of the economic damages, and discusses efforts to minimize these interactions.
Since the passage of the Marine Mammal Protection Act (MMPA) of 1972, populations of California Sea Lions have increased, until today their numbers are reported to be larger than at any other time in the past several centuries. This is a case of a federal law being too successful. In 1997, a report co-authored by the National Marine Fisheries Service (NMFS) and the Pacific States Marine Fisheries Commission offered Congress some sound recommendations for changes to the MMPA, aimed at beginning to place some management controls on this exploding population. Eleven years later, not one of the recommendations has been implemented, and there has been no reauthorization of the MMPA. A number of incidents have pointed up the fact that injuries of humans by sea lions have been increasing, and some regulatory changes are needed now to slow down the aggressive packs of sea lions. In addition, more and more property damage has been reported, both against boats and on the docks in marinas, up and down the coast. We no longer have the luxury of ignoring what is becoming a very serious public problem. The sportfishing industry is working for changes in the MMPA and for appropriate funding, and is asking Congress to direct the NMFS to take the lead in the development of effective non-lethal deterrent devices, so as to allow the industry to co-exist with these marauding gangs of pinnipeds. The funding would create the incentives so that the private sector would partner with NMFS in developing the needed deterrent devices.
Preliminary Observations of the Effectiveness of Non-Lethal Deterrence Methods for California Sea Lions and Pacific Harbor Seals along the Coast of California
Since the Marine Mammal Protection Act (MMPA) of 1972 became a law, many pinniped populations have increased and expanded their range along the west coast of the United States (e.g., California sea lion, Pacific harbor seal, northern elephant seal, northern fur seal, Steller sea lion, etc.). Pinnipeds live primarily in the ocean but rely on coastal areas for important components of their existence (i.e., pupping and resting). As pinniped populations increase along the California coast, numbers of animals hauling out on beaches, rocky substrates, and non-traditional areas such as marinas, docks, and bait receivers have also increased. Confrontations between humans and pinnipeds are escalating. The National Marine Fisheries Service is assigned by the Federal Government to actively manage these species and their interactions with humans. These confrontations have been, in part, a result of competition between people and pinnipeds for prime coastal areas/habitat. The human responses to these interactions have included modification of marine areas used by these animals, but have also included harassment that can lead to injury or death of the animals. Pinnipeds, however, are fully protected from harm under the MMPA. The MMPA Amendments of 1994 provided new authority to citizens of the United States to deter marine mammals from damaging private property, endangering public safety, or damaging public property. A number of non-lethal deterrence methods exist, including physical barriers such as fences and negative stimuli such as sprinkler systems, rubber shot, and acoustics. In most cases, seals and sea lions become habituated to deterrence methods over time. We discuss preliminary results of the use of non-lethal techniques along the coast of California to exclude seals and sea lions from hauling out on marinas, docks, and bait receivers. Preliminary observations indicate that the placement of physical barriers and sprinkler systems has resulted in consistent non-lethal deterrence of sea lions from bait receivers and docks.
Vertebrate pest management characteristically focuses on research and development of control tools and their application. Similarly, integrated pest management (IPM) principles focus on control methods and habitat alteration to reduce risks from pest species. Organizational structure, administrative elements, and program management are rarely identified as key components of IPM or the development and execution of vertebrate pest strategies; however, they should be included when seeking sustainable and costeffective programs. In urban areas, rodent control programs typically are reactionary and uncoordinated rather than preventative and systematic, resulting in short-term results that cannot be sustained. Use of an environmental management system (EMS), as described by ISO 14001 standards, establishes program structure and priorities for improvement. As part of the EMS, an Aspect Register can be used to identify risk factors and specific mitigation measures; for example, this can be done on a national scale to rank cities at greatest risk of rodent infestations or for program development and execution within an individual city block or building. Emphasis on program and systems management, organizational skills, risk factors, multi-disciplinary training, and prevention is needed as part of vertebrate pest management. Technology often is not the limiting factor; rather it is administrative and management elements for sustainable and effective program execution.
The concepts of “integrated control” and “integrated pest management” (IPM) were devised by entomologists, but they proved relevant to the monitoring and control of virtually any agricultural pest (i.e., weeds, fungi, vertebrates). Within IPM, economic threshold characterized pest densities that would have negative impacts and economic injury level characterized amounts of predicted crop injury (destruction) that would allow recovery of potential pest-control costs. Approximately 150 species or groups of vertebrates have been documented to pose human health/safety risks or to cause agricultural, natural resource, and property losses in North America. Rodent (e.g., mice, rats, ground squirrels) and bird (e.g., blackbirds, gulls, cormorants) populations are the most frequently cited species/groups of vertebrates linked with IPM. Uncertainty characterizes IPM applications to control damage by these species/groups. Uncertainty is a measure of variance, which occurs due to the myriad of biological, crop, economic, meteorological, pesticide, production, seasonal, and soil unknowns that impact IPM programs. Six uncertainty-reduction techniques are commonly used by economists: 1) worst-/best-case scenario, 2) contrived scenarios, 3) decision tree analysis, 4) sensitivity analysis, 5) Monte Carlo simulation, and 6) systematic projections. This paper reviews key IPM literature, especially economic literature, and discusses techniques that can reduce the economic uncertainty of using IPM programs with vertebrates.
Developing Standard Operating Procedures for Wildlife Damage Management Activities in Urban and Suburban Areas in Southern Nevada
Urban and suburban areas of southern Nevada are affected each year by a wide variety of wildlife species that cause damage to property and cause concern for human health and safety issues. Integrated wildlife damage management practices are employed in cases where technical assistance and direct control measures are used to resolve problems with wildlife. Nevada’s daytime temperatures often exceed 115ºF (46ºC); therefore, traditional management practices have evolved to match the climate. Nevada is currently the fastest-growing state in the nation, so wildlife damage management practices are ever changing. The increase in urban sprawl provides additional food and habitat availability for several species of wildlife. Anthropogenic food sources produce an unnatural environment. Wildlife damage management activities are therefore needed to resolve a variety of conflicts. These standard operating procedures for wildlife damage management in urban areas were developed to better manage wildlife complaints. Wildlife species collected during damage management activities are tested for various diseases and contaminants.
Comparison of Electrified Mats and Cattle Guards to Control White-Tailed Deer (Odocoileus virginianus) Access through Fences
White-tailed deer pose economic and safety concerns for agricultural and transportation industries that may be addressed by reducing their access to areas of concern. Here, we review research findings relative to the efficacy of an electric mat and cattle guard as means to reduce deer access to protected areas. Intrusions of deer across a prototype electronic mat were reduced an average of 95% from pretreatment levels. Deer intrusions across a simulated cattle guard were reduced by at least 88% from pretreatment levels. Comparisons of other cattle guard studies show that when flat material is used instead of rounded for cross members, deer cross the guard. Initial expense for electric mats is lower than for cattle guards, but electric mats will require higher maintenance input than guards. When used as part of an integrated deer control program, properly constructed and maintained electric mats or cattle guards can reduce deer intrusions into areas of concern.
Tetracycline hydrochloride (THC) is an ingestible antibiotic that produces a fluorescent mark on growing bone and may be combined with baits to aid ingestion by wildlife species. Feral pigs are an invasive species found throughout the United States. They are implicated in damages such as increased erosion, direct competition with native wildlife, destruction of habitat, disease transmission, and crop damage. Land managers are currently utilizing lethal and non-lethal control strategies to minimize damage. THC may be useful as a voluntary biological marker for feral pigs. Possible uses include mark recapture analysis, evaluation of large-scale movements, and determining the uptake of pharmaceuticals by feral pigs. We evaluated the palatability of THC for feral pigs, dosage necessary for adequate marking, and time necessary between ingestion and identification of marks. We found that feral pigs will consume THC when combined with palatable baits, that >150 mg THC is necessary for adequate marking, and that marks can be identified in teeth ≤7 days post ingestion.
Public interest in capture devices and potential injuries to animals has resulted in changing of trapping regulations in a variety of states and countries. Within the U.S., some states have revised trapping regulations to require more frequent trap-check intervals. Such regulatory changes may impact the USDA Wildlife Services (WS) Operational Program by reducing the ability of WS specialists to efficiently provide services over wide areas. Remote trap monitors, however, may provide a technology that can assist WS in meeting new trap check requirements. The National Wildlife Research Center’s (NWRC) Logan, Utah Field Station recently assisted with the distribution, operation, and evaluation of radio-telemetry trap monitors by the WS Operational Program. Transmitters, receivers, antennas, and on-site training were provided to personnel in 7 states in 2005 and 16 states in 2006. Feedback from the states receiving trap monitors indicated that trap monitors, when used in appropriate situations, could save WS specialists time and resources, but the monitors were most useful in areas where traps or other capture devices are difficult to access and radio signals can be heard from the greatest distance. Improved designs (using cell phone and satellite technology) could be helpful in other situations in the future.
The Use of a Remote Cellular Driven Digital Camera System (Smart Scouter™) for the Evaluation of OvoControl® P (Nicarbazin) Bait Acceptance in Feral Pigeons (Columba livia)
Originally developed as a remote trail camera system for monitoring deer, ERS Group of Atlanta, GA has combined the advantages of digital imaging together with cellular telephone technology into a “Smart Scouter™”. By combining a motion and heat sensing digital camera, this system can record movement at the target site and upload the images immediately to both a website and email providing real time monitoring details. We describe the use of the Smart Scouter™ camera system for monitoring pigeon numbers and non-targets feeding at site where OvoControl® P bait was applied, without intervention by technicians. The camera system can augment required monitoring when applying OvoControl® P bait. It is especially useful in remote or hard-to-access areas, and can save time and labor costs.
The resolution of conflicts between human and wildlife interests often involves lethal control to reduce problem wildlife populations. However, lethal control has always had its limitations, the acceptable methods are becoming fewer, and public opposition is on the increase. Fertility control offers a potential alternative approach that is widely regarded as being inherently more benign. Furthermore, in some circumstances fertility control may have specific advantages over culling. The development of “single-shot” injectable immunocontraceptive vaccines that inhibit the fertility of individual animals for several years is leading to practical applications that exploit this novel technology. Further advances can be expected to lead to the emergence of a new generation of wildlife management tools. A key issue in this process is predicting what the population consequences will be for a particular species, given a specific level of induced infertility. Here, we use population modelling techniques to explore how much fertility control is enough to achieve different levels of population reduction, how long it will take to realise these reductions, and to understand how these effects are shaped by the population biology of the target species. This offers some generic conclusions, with low levels of infertility having little impact on species with high population turnover rates, while modest levels of infertility may yield useful population reductions for species with low intrinsic rates of increase, although such effects take longer to be realised in long-lived species. We also observed that there is potential for optimising the intensity of induced infertility, in terms of the proportion of breeding animals rendered infertile, and the frequency of application; so, for instance, biennial application could be more efficient than annual application for some forms of fertility control in certain species. There is increasing evidence from field studies that the survival of infertile animals is enhanced, probably because they do not incur the costs of reproduction. Our model predicts that this effect will be of limited importance for short-lived species with high intrinsic rates of increase, but it is more likely to compromise population reduction in long-lived species. We suggest that the generic modelling approach can help develop an evidence-based platform for discussing when fertility control can be regarded as a feasible, desirable, and sustainable option to manage problem wildlife.
Recently, wildlife contraception became a reality with the registration of OvoControl for geese and pigeons. A data submission to the Environmental Protection Agency for the registration of GonaCon™ for white-tailed deer is forthcoming. The question that is now facing wildlife managers is if, and how, to implement contraception as part of an overall management plan. Population models offer a method of predicting the long-term efficacy of management actions without investing time and money in expensive field studies. Black-tailed prairie dogs were used as a target species for the purposes of these models. Four different management options were modeled for a 100-year period including no control, lethal control only, fertility control only, or a combination of lethal and fertility control. Yearly culling resulted in a more rapid rate of population decline than yearly contraception. Culled populations (50-90% culling) went extinct more quickly than populations contracepted at the same rate. Populations could be stabilized at their current size with 12.79% yearly culling or 33.25 % yearly contraception. Populations also remained relatively stable over 100 years when 50% of the population was culled initially, followed by 85.8% contraception once every 3 years. These models will help provide a scientific basis for further discussion on the usefulness of wildlife contraceptives, and will help highlight the areas that need further research.
Resident populations of two exotic deer species, fallow deer and axis deer, are having adverse impacts on their habitat and on native plant and animal communities at Point Reyes National Seashore (PRNS) in California. These non-native cervids were released intentionally for recreational hunting on the property now known as PRNS during the period 1942-1954. Approximately 860 fallow deer and 250 axis deer now inhabit PRNS. Under an approved non-native deer management plan, fallow and axis deer populations will be removed from PRNS by 2021 via culling of animals by sharpshooting and by treatment of some of the female fallow deer with GonaCon™ Immunocontraceptive Vaccine. During July-August 2007, 69 fallow does were captured, equipped with numbered ear tags and radiotelemetry collars, and injected with GonaCon™ vaccine before being released. Control animals include 10 does that were captured, marked, and given “sham” injections during July-August 2007, and 19 does that were captured and marked (but not injected) during 2005. Reproductive activity, as indicated by lactation and fecal concentrations of progesterone among the GonaCon™-treated and control does, will be monitored and compared for two years, and will be used to determine the efficacy of GonaCon™ as a cervid contraceptive agent. Traditional methods of population control, such as regulated harvest by licensed hunters, often are impractical or illegal in settings such as national and state parks, and the use of firearms may be prohibited in some urban and suburban environments. The development of safe and effective wildlife contraceptives such as GonaCon™ is needed to control locally overabundant populations in situations where traditional management tools cannot be employed.
Long-Term Efficacy and Reproductive Behavior Associated with GonaCon Use in White-Tailed Deer (Odocoileus virginianus)
GonaConTM is a single-shot immunocontraceptive vaccine that targets the reproductive hormone gonadotropin releasing hormone (GnRH). The GnRH peptide used in the vaccine is secreted by the hypothalamus of the brain and is specifically known as luteinizing hormone releasing hormone. This peptide stimulates the synthesis and secretion of luteinizing hormone and follicle stimulating hormone by the anterior pituitary gland. These hormones in turn stimulate hormone and gamete production by the ovary. In earlier studies with deer, we showed that antibodies produced in response to a single shot of GonaCon inactivated endogenous GnRH and greatly reduced fertility, reproductive steroids, and associated behaviors for at least 2 years. In the present study, we report on contraceptive efficacy and behavioral observations up to 6 years after female white-tailed deer were given a single shot of one of several formulations of GonaCon. We compared the standard GonaCon made by conjugating the GNRH peptide to keyhole limpet hemocyanin (GonaCon-KLH) to one with the GnRH peptide conjugated to a blue mollusk protein (GonaCon-Blue) and to a 2-shot regimen with GonaCon-KLH. All GonaCon preparations were made into an emulsion with AdjuVacTM and administered to 5 mature female deer per treatment. The results showed that the GonaCon-Blue preparation significantly out-performed the other single-shot vaccines, as well as the 2-shot regimen of GonaCon-KLH, with efficacy of 80-100% for each of the 5 years in the study. Interestingly, expression of estrous behavior was minimal in Years 1-2 following treatment for all groups, but expression of estrus increased in later years of the study, even though does remained infertile. This expression of estrus and fertility was reversed with follicle stimulating hormone releasing hormone (FSH-RH) peptide conjugated to a mollusk protein and mixed as an emulsion with AdjuVac. This suggests that does possess an FSH-RH peptide, secreted by the hypothalamus, which modulates follicle development and resulting estrogen production and reproductive behavior.
Immune Mechanisms and Characterization of Injection Site Reactions Involved in the Multi-Year Contraceptive Effect of the GonaCon™ Vaccine
The term “vaccine” has traditionally been associated with establishing immunity (antibodies) to a disease. This immunity is usually developed following administration of killed microorganisms. Disease vaccines typically require 1 to 3 injections, depending on the antigen design and efficacy of the vaccine. The effectiveness of the disease vaccine depends on the immune response developed by the host following exposure to the disease organism. The immunocontraceptive vaccine GonaCon™ is designed to produce immunity to the “self” hormone (GnRH), which is essential to reproductive activity in the mammal. Antibodies to GnRH reduce its biological activity resulting in infertility of both sexes. GonaCon™’s effectiveness as a single-injection immunocontraceptive wildlife vaccine depends on 4 factors. The first is the use of a large foreign mollusk protein in the GnRH conjugate. Second is the design of mollusk/GnRH protein conjugate that presents the GnRH antigen in a repetitious fashion. This design mimics the “danger signal” found in bacterial pathogens to which the animal has been previously exposed. Third is the addition to the vaccine of micrograms of Mycobacterium avium, which is ubiquitous in the environment and activates memory cells. The fourth factor is use of a water-in-oil emulsion, which provides a depot at the injection site, allowing a slow release of the vaccine. With this formulation, the vaccine is presented to the body as a “chronic infection”, even though it is not infectious. The granuloma that normally develops at the injection site plays a prime role in the host’s defense against this “chronic infection”. A WHO report on the use of the alum adjuvant in human vaccines states that “development of a small granuloma is inevitable with vaccines adjuvanted with aluminum, and is to be considered necessary to the efficacy of the adjuvant.” Researching GonaCon™ for use in companion animals, NWRC has looked at many different adjuvants intended to reduce the injection site reaction while at the same time retaining an effective vaccine. This paper reports on the role of the adjuvant and the injection site on the effectiveness of the vaccine.
Oral Vaccination and Immunocontraception of Feral Swine using Brucella suis with Multimeric GnRH Protein Expression
As part of the Reproductive Control Methods Project, the USDA National Wildlife Research Center (NWRC) has developed multiple non-lethal contraceptive tools to control population of over-abundant wildlife species. Working in conjunction with Dr. G. P. Talwar of the Talwar Research Institute in India, scientists at NWRC have shown that a recombinant form of GnRH peptide has successfully contracepted swine. Feral swine not only pose a significant agricultural issue due to over-population; they act as a reservoir for Brucella suis, a threat to domestic livestock and humans. The Brucella abortus RB51 (Rough Brucella) vaccine, developed for bovine brucellosis and licensed by the USDA Animal Plant Health Inspection Service, has shown protection for some swine and is also effective against Brucella suis infection and other antigens. There is currently no approved vaccine for swine brucellosis (feral or domestic) in the United States. Past studies performed at The Ohio State University show that Brucella suis vaccination appears to protect against abortion and colonization in pigs after a virulent challenge. The Talwar recombinant peptide consists of 5 LHRH peptides interspersed with 4 universally immunogenic “promiscuous” T-cell epitopes of diverse genetic background. By transforming the Brucella suis strain with the Talwar recombinant LHRH plasmid, the bacteria will produce both its own host proteins, and the LHRH protein. A systemic immune response should then be generated to the Brucella suis proteins being produced, allowing for vaccination to Brucella suis. In addition, an immune response would be generated to the LHRH proteins resulting in antibody production and immunocontraception. A broad range of applications can be proposed utilizing the recombinant LHRH, such as other dual vaccines and scale-up production of a low-cost single-injection LHRH vaccine.
Mycobacterium avium: Is It an Essential Ingredient for a Single-Injection Immunocontraceptive Vaccine?
Greater demand for non-lethal means of alleviating human-wildlife conflict has led to an interest in contraception as a wildlife management tool. The development of a single-injection Gonadotropin-Releasing Hormone (GnRH) contraceptive vaccine by the USDA National Wildlife Research Center reduces logistical limitations and the cost of using a vaccine that requires 2 injections. This study assesses the efficacy of different GnRH-KLH (keyhole limpet hemocyanin) vaccine designs. Forty-two captive female black-tailed deer were divided into 3 groups. A control group was injected with saline solution, and 2 treated groups were given either GonaCon™, a GnRH vaccine paired with AdjuVac™ (an adjuvant containing 175 µg of killed Mycobacterium avium), or GnRH vaccine without AdjuVac™ (instead substituting DEAE-dextran/oil (DD) as the adjuvant). Pregnancy rates in deer treated with GonaCon™ were significantly reduced as compared to saline controls (P = 0.006). There was no significant difference between GnRH-DD compared to saline (P = 0.297). Significant difference was found between GonaCon™ and GnRH-DD (P = 0.055). Vaccinated does that remained fertile received booster injections according to treatment group and were administered either GonaCon™ containing 87 µg M. avium or GnRH-KLH conjugate bound to DEAE-dextran. Deer that received booster injections regardless of the adjuvant were 100% contracepted for 1 year. Six out of 10 deer that received a prime injection of GonaCon™ remained 100% contracepted for 3 years, suggesting that the killed M. avium in the adjuvant is essential for the success of GonaCon™ as a single-injection GnRH vaccine.
Traditional methods of prairie dog management are not always practical or acceptable. Therefore, other methods need to be developed to aid managers responsible for prairie dog management. Contraception is one such method being developed at the National Wildlife Research Center (NWRC). GonaCon™, an immunocontraceptive vaccine, has shown promise for other species when administered as a single shot. A laboratory dose-response study and a field study using GonaCon™ with black-tailed prairie dogs are being conducted concurrently at NWRC. DiazaCon™ is an oral contraceptive that resulted in a 47% reduction in the number of pups/adult in a preliminary field trial. However, treatment was administered late in the breeding season in that trial. A new field study is currently underway to examine the effects of DiazaCon™ on reproduction when administered to black-tailed prairie dogs just prior to the breeding season.
Cost Effectiveness of OvoControl G® for Managing Nuisance Canada Goose (Branta canadensis) Populations: A Comparison of Theory and Field Applications (Abstract only)
OvoControl G® is a relatively new product that reduces the hatchability of Canada goose (Branta canadensis) eggs. However, little data is available on the cost of application. We present a model for estimating the cost of application of OvoControl G for managing nuisance Canada goose populations and compare that model to the cost and results of field-based 2 applications in Oregon. Our model showed that at low goose densities, fixed labor costs are responsible for a significant portion of the total cost. As goose densities increase, these fixed costs become equivalent to, and eventually less than, the costs associated with the purchase of the product. As we expected from the model, the cost of applying OvoControl is high compared to the actual reduction in reproduction. However, even with this apparently high cost, cooperators were pleased with the results. We also present several scenarios that managers may employ to further reduce the cost of application.
The most important reservoir of wildlife rabies on the American Great Plains is the striped skunk. A rabid striped skunk taken in August 1988 near Deaver, WY became the index case for a subsequent epizootic in a previously skunk rabies free area. In 1989, more rabid skunks occurred and the epizootic was moving throughout Sage Creek and in later years (1990-1993) through the entire Shoshone River basin. Federal, state, and local officials cooperated in a rabies program with the goal of addressing the health and safety of the region’s citizens, domestic animals, and livestock. Three areas of focus in the program were: 1) immunization of pets and livestock, 2) public education, and 3) skunk population monitoring and control. Rabies immunizations were re-emphasized by the local veterinarians and public health officials for pets to decrease potential rabies spillover to other species. Public education emphasized the dangers of rabies and the behavior of rabid animals using local news media and assemblies at area schools. This paper provides a synoptic overview of the third component – skunk population monitoring and control provided by USDA/APHIS’s Wyoming Wildlife Services (WS). WS provided trapping expertise starting in 1990 with rabid specimens identified by the Wyoming State Veterinary Laboratory. Starting in 1990, WS’s National Wildlife Research Center provided data analysis of rabid locations for the entire epizootic (i.e., 1988-1993). These analyses demonstrated the epizootic’s movements through the novel first use of a Geographic Information System that merged a wildlife disease (i.e., rabies) case/capture locations and dates with additional GIS data layers including hydrology, human population density, and land use. The epizootic ended in 1994 with striped skunks, bats, cats, and one horse affected. Studying this epizootic should benefit officials in planning future surveillance and/or depopulation programs. This study demonstrated the need for a skunk rabies vaccine and effective delivery system, and if the latter had been available maybe this epizootic would have been more limited in its scope and duration.
Rabies remains a globally significant zoonotic disease, but rabies control is achievable under certain circumstances. Canine rabies has been eliminated from the U.S.; however, approximately 55,000 humans die annually worldwide from the disease. In the U.S., economic losses continue to be substantial and the risk to humans and domestic animals has not been eliminated. As an example of the complexity of rabies management, we describe a local rabies control program and efforts to restore Cape Cod, MA to terrestrial rabies-free status, after a 2004 oral rabies vaccination (ORV) barrier breach following 10 years of rabies-free status. The emergence of raccoon rabies in southeastern New England in 1992 prompted the U.S. Centers for Disease Control and Prevention, the Tufts Cummings School of Veterinary Medicine, and the Massachusetts Department of Public Health to begin an ORV program to reduce the occurrence of carnivore rabies in an area directly adjacent to the Cape Cod Canal. In 2001, USDA APHIS Wildlife Services began full-time collaboration on the Cape Cod Oral Rabies Vaccination Program (CCORVP) as part of national wildlife rabies control efforts. The primary objective of the CCORVP was to use ORV in tandem with the physical barrier created by the Canal to prevent the spread of rabies to peninsular Cape Cod, a heavily-populated tourist destination southeast of Boston. After an increase in rabies cases within the traditional Cape Cod ORV zone, ORV bait distribution efforts were modified to reduce the risk of rabies spread onto the Cape. In spite of these modifications, raccoon rabies was detected for the first time on peninsular Cape Cod in March 2004. A trap-vaccinate-release campaign, removal of suspect raccoons and skunks, and expanded ORV efforts were unsuccessful in preventing the spread of the virus. Rabies surveillance became the priority of the Cape Cod Rabies Task Force. In 2006, rabies was finally detected at the eastern extremity of the peninsula. In this paper, we summarize ORV efforts, explore possible causes for the spread of raccoon rabies onto the Cape, summarize several small-scale Cape Cod rabies research projects, and suggest a 5-year plan for future Cape Cod rabies controls efforts.
Potential Food Item Distractions during Raccoon ORV Baiting Campaigns on Cape Cod, Massachusetts: Would You Like Fries With That?
USDA APHIS Wildlife Services has been a primary cooperator in the Cape Cod Oral Rabies Vaccination Program (CCORVP) in southeastern Massachusetts since 2001. The CCORVP (1994 - present) was originally designed to reduce the incidence of terrestrial rabies adjacent to the Cape Cod Canal in order to prevent its spread on to peninsular Cape Cod. However, since the barrier breach in 2004, CCORVP is now focused on rabies control in this coastal resort area southeast of Boston, MA. An integral component of wildlife rabies management is oral vaccination with vaccine-laden baits. Consequently, maximizing bait uptake rates is critical to achieving sufficient population immunity to reduce rabies prevalence and achieve control. To that end, knowledge of raccoon food habits, especially at ORV bait delivery times (spring and fall on Cape Cod) is crucial. We undertook a study of raccoon food selection in southeastern Massachusetts to assess the presence of and interest in competing food resources. We collected intact stomachs from raccoons found dead or euthanized for rabies testing within the CCORVP zone during 2006 (n = 33) and 2007 (n = 109) for analysis. Stomach contents were dominated by vegetation (80%), followed by invertebrates (43%), non-food items (41%), vertebrates (35%), and hair (primarily raccoon based on appearance) (15%). Food item occurrence appears to be related to age. We present findings, potential management implications, and suggestions for assessing food use related to rabies control in other locations.
The raccoon variant of rabies is distributed throughout the eastern and southeastern United States. Historically, the westward spread of raccoon variant rabies has been prevented by geographical barriers and the distribution of oral rabies vaccines (ORV). In 2004, raccoons positive for raccoon variant rabies were discovered beyond the vaccination zone in northeastern Ohio, suggesting the potential westward spread of the disease. To evaluate the potential westward spread of rabies across Ohio, we are employing two strategies: telemetry, and genetics. We are radio-tracking raccoons to determine which factors, if any, may be considered barriers or corridors to raccoon movement. In addition, we are collecting genetic samples from raccoons in urban and rural areas in 9 distinct regions of northeastern Ohio. These samples will be used to evaluate relatedness between raccoon populations. We hypothesize that the degree of genetic relatedness will be proportional to the distance separating populations. Populations showing less or more relatedness may be indicative of barriers or corridors to movement, respectively. Preliminary movement data suggest that raccoons are remaining within their home ranges in greenbelt areas, although some have traveled over 2.0 km into urban and suburban areas before returning. Genetic sampling is 45% complete, and analysis will be performed once all samples have been collected. The results from this study will provide a more thorough understanding of raccoon movement in northeastern Ohio. This information will allow researchers to recommend ORV bait distribution strategies to more effectively stem the westward spread of raccoon variant rabies.
Risks Associated with the Transmission of Bovine Tuberculosis from White-Tailed Deer to Cattle in Michigan: Current Research
Bovine tuberculosis (bTB) is a contagious disease of livestock, wildlife, and humans. Typically, it is transmitted through inhalation of aerosolized bacilli and direct or indirect contact between animals. In northeastern Michigan, bTB is endemic in white-tailed deer, and evidence suggests deer have spread the disease to domestic cattle. Previous research indicates bTB transmission likely occurs through contamination of cattle feeding sources by infected deer and subsequent use by cattle. We are investigating deer movements in relation to farm management practices such as feeding schedules as well as locations of cattle feeding areas, hay storage sites, barns, and water sources. All locations are plotted using ArcMap software. Regular communication with cooperators allows for updates in feeding schedules and locations. We are capturing free-ranging whitetailed deer and fitting them with radio collars equipped with a global positioning system (GPS). As of 15 February 2008, we have retrieved GPS collars from 7 of 16 deer collared in 2007, and 7 new collars have been deployed since 1 January 2008. Each retrieved collar has recorded over 2,500 data points, and preliminary results suggest individual deer are staying within 1.5 km of their capture site. Spatial analysis on deer locations relative to livestock management practices and farm structures will take place when all data is retrieved in late 2008 and early 2009. Once complete, we hope this information will allow us to recommend mitigating measures for livestock producers to reduce the risk of transmission of bTB from free ranging whitetailed deer to domestic cattle.
Kansas is a major producer of livestock and has an abundance of over-wintering European starlings. Roost sizes for over-wintering starlings can be as large as 5 million individuals. Starlings cause a substantial amount of economic damage to farmers. Escherichia coli O157:H7 and Salmonella can cause illness in both livestock and humans, and cattle with Johne’s disease must be culled. Crohn’s disease in humans is suspected to be caused from Mycobacterium avium subsp. paratuberculosis (Johne’s disease). We banded, leg-flagged, and radio-tagged starlings using feedlots near Great Bend, Kansas. Our objectives were to track daily movements of starlings visiting feedlots in this area and screen starlings for E. coli O157:H7, Salmonella spp., and M. a. subsp. paratuberculosis. Preliminary data show that starlings in Kansas are moving among feedlots rather than remaining at one feedlot. Pathogens were detected at a low prevalence. Our results can be used to develop plans for the management of transmissible diseases carried by starlings.
The Ecology and Surveillance of the Deer Mouse Peromyscus maniculatus in San Diego County, California
Sin Nombre virus is the etiologic pathogen of hantavirus pulmonary syndrome. In the U.S., this pathogen is carried by the deer mouse. The deer mouse is more prevalent than any other mammal in North America. The biology and behavior of the deer mouse is described. Disease surveillance is critical and is conducted by monitoring reservoir populations; early detection can help prevent the possible spread of disease to human populations. In San Diego County, annual surveillance has been conducted since 1994, with the percentage of positive deer mice ranging from 0% to 5.3%, with an average of 2.6% positive. Preventive measures to reduce human – hantavirus contact are recommended.
The Economic Impacts of Bird and Rodent Damage to California Crops: A Methodology to Select Counties for Input-Output Modeling
California is the nation’s greatest agricultural producer. In 2006, California’s gross value of agriculture production was more than $38.3 billion, almost double the value of production for the second most important agriculture state, Texas. The agricultural sector is a fundamental segment of any economy because it not only contributes substantially to the general economy and employment of the region, but it is additionally linked to almost all other sectors in the economy (i.e., manufacturing, retail trade, and accommodation and food service) as a source of inputs. Damage to crops by birds and rodents can reduce total crop yield and increase pest control costs. This ultimately reduces the production output of the agricultural sector and all other linked sectors and could potentially have significant total economic impacts. One method to estimate the total impact to the California economy of a decrease in agricultural yields and increase in pest control costs as a result of bird and rodent damage is an input-output (IO) model. To capture the sub-regional effects of economic changes, IO modeling is done at the county level. For the initial phases of this project, a deductive process was used to systematically rank California counties according to gross value agricultural production, value of production of targeted crops, and concentration of targeted crops. This process was used to identify the 10 leading agricultural counties, out of California’s 58, that will be processed for IO modeling to measure economic impact of bird and rodent damage on employment and revenue in each of these counties.
In May 2007, The Humane Society of the United States launched a for-fee business called Humane Wildlife Servicessm to engage in wildlife control jobs in the Washington, D.C. metro area. We had several purposes in launching this service. First, we felt it necessary to offer a service to customers in our home base area that allowed them to choose a wildlife removal company that did not trap and relocate, or trap and kill, animals. Second, we wished to directly experience and test the operational and conceptual challenges associated with this sort of service. Third, we wished to develop a model that could eventually be shared with others wishing to provide similar services in their communities. This paper describes how this operation works and discusses some of the concepts underlying what we call a “humane” wildlife service.
Animal protectionists John Hadidian, Camilla Fox, and William Lynn exhorted wildlife professionals to engage the ethical issues associated with wildlife damage management. After outlining several ethical principles, they raised three common “nuisance” wildlife scenarios to illustrate the ethical difficulties they believe need thoughtful consideration. Despite their honorable desire, their paper exemplifies why the substantive dialogue on the ethics of wildlife control has not been achieved. First, their presentation neglected to wrestle with the role of competing worldviews. Second, the authors avoided acknowledging how animal protectionists’ rhetoric and behavior has undermined the trust necessary for wildlife managers to engage in dialogue. I conclude by offering several ways animal protectionists can build the fund of good will essential to initiating dialogue and finding common ground.
The watersnakes (Nerodia) are a group of semi-aquatic snakes native to North America, primarily east of the Rocky Mountains. Five populations of 3 watersnake species have become established in California. In the northern Sacramento area, more than 100 southern watersnakes (N. fasciata), including numerous gravid females, have been captured since their discovery in 1992. Thus far, this population is known from two tributaries of the American River. In southern California, another southern watersnake population is known from Harbor Park Lake, a semi-isolated urban lake in Los Angeles County. A population of northern watersnakes (N. sipedon) has become established in Roseville, CA, and until the mid-1990s a dense population of diamondbacked watersnakes (N. rhombifer) flourished at Lafayette Reservoir in Contra Costa County. These are potentially worrisome introductions because watersnakes share numerous traits with other invasive aquatic species, including a wide breadth of physiological tolerances, large native distributional ranges, and they occur in many different freshwater types. Watersnakes can be highly fecund, are viviparous, and readily disperse. They are generalist predators that coevolved with many of the aquatic vertebrates now inhabiting western waters. As such, introduced Nerodia pose potential threats to native wildlife, including special status species such as the federally-listed threatened giant gartersnake. To address issues surrounding the management, eradication, or control of Nerodia populations in the western states, concerned biologists formed the multi-agency Nerodia Working Group. Short-term goals of the group include experimental eradication/control of the southern California population, listing Nerodia as a restricted genus under Section 671 of Title 14 of California’s Code of Regulations, and conducting outreach to the pet trade and other groups to raise awareness about these potentially invasive species.
Hawai`i Volcanoes National Park acquired the 115,000-acre Kahuku Ranch Unit in 2003. The Kahuku Unit contains numerous exceptional natural resources including endemic plants and birds, many of which are federally listed threatened and endangered species. Eleven European mouflon sheep were introduced to Kahuku from 1968-1974 for private trophy hunting. Because Hawaiian plants did not evolve with mammalian herbivores, managers began to control the large mouflon population with a closely directed volunteer program. Since 2004, more than 1,900 mouflon have been removed through this program. We estimated that there were 2,586 ± 705 (90% CI) mouflon at Kahuku in November 2004, but by December 2006 the population decreased 30%. Although the ram:ewe ratio did not change significantly after this population decrease, the mean (±95% CI) overall ratio in 2004 was 1:2.4 (1:2.1-1:2.7) and 1:2.7 (1:2.4-1:3.1) in 2006. We found that 82.6% of adult ewes (n = 26) were pregnant with a single fetus in early 2007, and there was a significant increase in the number of lambs per ewe from 2005 to 2007 consistent with a density-dependent response. The maximum (±95% CI) number of lambs per ewe was 0.484 (0.412-0.558) in 2005 and 0.667 (0.587-0.750) in 2007. The directed volunteer program has been more successful in reducing mouflon abundance at Kahuku than species such as feral pigs elsewhere on Hawai`i Island, but some population-level responses such as increased reproduction could result from density decreases.