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 27, 2016
From the outset, humans evolved with severe conflict with wildlife, but which they mastered with great ingenuity. We are the only primate that can exist on the ground with large predators, day and night, and are not dependent on climbing trees or cliffs for security. Consequently, we regressed in climbing adaptations and body strength. Without that mastery over predators, there would have been no human evolution. This mastery led to a transfer of resources from predators and competitors to our self, followed very early by dispersal out of Africa into Europa and Asia. The archaeological record keeps hinting at predator-free conditions. At the end of the last glaciation, mega-faunal extinctions generated new challenges for humans, as the virtual absence of mega-herbivores profoundly changed the ecosystems, as fires replaced herbivores in consuming vegetation. Also, wolves escaped extinction, but not their enemies and competitors. Consequently, since the natural limitations on their numbers had been diminished, wolves had to be controlled, and native people rose to the task. Only in societies with disarmed citizens were wolves a menace, and legislation that frees wolves from human control eventually recreates that very menace. North America’s Pleistocene native wildlife survived under extremes in predation, such as was not experienced in Eurasia or Africa. Consequently, our native wildlife species, being quick and accurate learners, readily habituate and are very good at taking advantage of us. Problem wildlife may be created by humans’ irrational wishes which conflict with the biology of a species. This is well illustrated by current efforts at wolf conservation here and in Europe, where the unintended consequence is the assured destruction of the wolf as a species.
Wildlife resources in southern Africa are remarkably beautiful, ecologically indispensable, and culturally critical to people of the region. Unfortunately, those who reside in rural areas (veldt) face remarkable risks every day when living and dealing with lions, leopards, elephants, crocodiles, and other creatures that go “bump” in the night. The loss of human life and limb is higher than most would ever think. In addition, loss of livestock and crops to wildlife is widespread and can be locally severe. The significance and severity of human-wildlife conflicts in southern Africa seem to be an order of magnitude greater than in North America. During the last decade, I have had the good fortune to work on several projects, including field research, lectures, symposia, keynote addresses, internships, and a reference book dealing with human-wildlife conflicts in southern Africa. It has been a lifechanging experience. This paper provides details on the projects we have established to help resolve human-wildlife conflicts in southern Africa.
Wildlife-livestock conflict is an ongoing challenge for both livestock production and conservation efforts. Predator kills of livestock are a serious economic concern for most ranching operations. In particular, small livestock such as sheep and goats are vulnerable to native predators including mountain lions and coyotes. Despite this challenge, livestock can be a powerful tool for habitat restoration and biodiversity conservation in disturbance-adapted landscapes such as coastal California. In 2014 and 2015 we used 1,400 goats to graze habitat in the Santa Lucia Mountains, California. To prevent wildlife-livestock conflict, we tested a livestock protection strategy that combines several methods: night penning goats within a double, portable electric mesh fence; using two guarding dogs inside the pen with the goats; monitoring predators with wildlife camera-traps placed on the fence’s periphery; and placement of the pen near the herders’ camp. Despite a predator-rich environment, no goats were lost to predators, and the only predator captured on the wildlife camera-traps over 161 nights was a single coyote. Often, when lions or other predators depredate livestock, the animal is lethally removed to prevent further depredation events. Preventing predators from killing livestock protects both livestock and predators.
Wide-ranging large carnivores pose myriad challenges for conservation, especially in highly fragmented landscapes. Over a 13-year period, we combined monitoring of radio collared pumas with complementary multi-generational genetic analyses to inform puma conservation in southern California. Our goals were to generate survivorship estimates, determine causes of mortality, identify barriers to movement, and determine the genetic and demographic challenges to puma persistence among >20,000,000 people and extensive urban, suburban, and exurban development. Despite protection from hunting, annual survival for radio collared pumas was surprisingly low (55.8%), and humans caused the majority of puma deaths. The most common sources of mortality were vehicle collisions (28% of deaths), and mortalities resulting from depredation permits issued after pumas killed domestic animals (17% of deaths). Other human-caused mortalities included illegal shootings, public safety removals, and human-caused wildfire. An interstate highway (I-15) bisecting this study area, and associated development, have created a nearly impermeable barrier to puma movements, resulting in severe genetic restriction and demographic isolation of the small puma population (~17-27 adults) in the Santa Ana Mountains west of I-15. Highways that bisect habitat or divide remaining “conserved” habitat, and associated ongoing development, threaten to further subdivide this already fragmented puma population and increase threats to survival. This study highlights the importance of combining demographic and genetic analyses, and illustrates that in the absence of effective measures to reduce mortality and enhance safe movement across highways, translocation of pumas, such as was done with the endangered Florida panther, may ultimately be necessary to prevent further genetic decline and ensure persistence of the Santa Ana Mountains population.
Science and Scholarship Abused, and the Counter-Productive “Conservation” of Wolves in North America and Europe
Although science forms the basis of wildlife conservation in the North American Model of Wildlife Conservation, advocacy and inadequate scholarship have led to conservation legislation that is destroying the wolf as a species. “Wolf science” is flawed due to the denial of historical information about wolves, ignoring how wolves explore new prey, ignoring long-standing research on the social organization and its changes in wolves, ignoring hybridization as a cause of the genomic extinction, the use of genetic data without a taxonomic verification of specimen, misuse of mathematics, and espousing meaningless statistics. Wolves cannot be conserved as a species in settled landscapes. So called wolf conservation in North America and in Europe is in need of reevaluation, as it is destroying a genuine canid species.
Habituation of wildlife, deliberate or accidental, can be a useful tool in research, a profitable tourist attraction, a serious nuisance, and even a mortal danger. It is the first stage of an animal gaining familiarity with humans and is always a state of unconsummated interest by the animal in us. The next stage following habituation, taming, is always initiated by a habituated animal, which thereby continues gaining information about us. In some carnivores this may be an attack to test for edibility. Even tame animals may continue to explore humans by addressing us in their species-specific sign language as if we were social companions of their own species. In my work with free-living but tame bighorn sheep, females began to treat me as a super-female, while males addressed me with dominance displays and attacked me. Since the sign language of different species of mammals may be unintelligible to us, it has led to “unpredictable” fatal attacks in zoological gardens and national parks. In reality, species that are testing us for dominance will signal the intention to attack redundantly and long before it happens. Inability to read the body language, coupled with ignorance of a species’ biology can have fatal consequences. Exemplary is a large and rather safe tourist industry that has developed around habituated and tame bears in North America, while some persons have lived with tamed black and grizzly bears for decades. Negative conditioning to habitat can lead to deliberate or inadvertent population crashes. The survival of large predators may depend on systematic conditioning to avoid humans. Cannibalism among predators involves larger stalking smaller, with predators made wary of being stalked. It is proposed that by targeting stimuli to which large carnivores cannot habituate, such as the sounds of stalking or the bold behavior of armed humans, they can be systematically conditioned to avoid humans. Inefficient and enduring hunting does that, generating a “Freedom of the Woods” – that is, safety for all outdoor users.
Among the many topics discussed under the broad category of urban ecology, few are as contentious as the management of unowned free-roaming cats. Like any public policy, the policies intended to effectively manage the population of these cats must, in addition to meeting other criteria (e.g., reflect broad public interest, economic feasibility, etc.), be based on sound science. Although many communities across the country have implemented programs based on the trap-neuter-return (TNR) method of managing “feral” cats, such efforts are often met with significant opposition by those claiming to have science on their side. However, this review of one of the most-often cited research papers on the subject reveals a number of significant shortcomings that undermine such claims. Public policy justified by such work is likely to prove costly and ineffective, and will very likely increase any legitimate threats unowned free-roaming cats pose to wildlife, the environment, and public health.
The oil produced by the anal glands of the striped skunk is known to be a strong deterrent to potential predators. However, it is also a common ingredient in many trap lures, especially those for carnivores such as the coyote. This paradoxical nature of skunk oil being both attractive and aversive has yet to be investigated, leaving a gap in the understanding of how predators of skunks respond to visual and olfactory information. In this project, camera traps with baited skunk models with either black-andwhite or brown pelage were deployed in natural areas around Southern California in order to study the effects of skunk oil and pelt coloration on predator behavior. Our study found scented models were less likely to be visited, indicating an avoidance of the oil and its scent.
In 2001, Marin County, California, replaced its USDA Wildlife Services (WS) cooperative predator damage management program with a county-run program that emphasized non-lethal methods for preventing and controlling coyote predation on sheep. This new “Livestock Protection Program” cost-shared with livestock producers’ efforts to improve fencing, obtain and maintain guard animals, and other such non-lethal methods, and initially it compensated producers for documented losses to predators. We surveyed sheep producers in Marin County in an effort to review the program over the past 15 years, evaluating the program in relation to livestock production, economics, predation management, and other measures of producer satisfaction. Lack of standardized data collection during the current program complicates its evaluation; however, from available information, we conclude the number of sheep and lambs are being produced in Marin County has continued to decline; some producers left the sheep business and other who remain graze less acreage with smaller flocks; predation by coyotes remains a high concern to producers; and most producers are dissatisfied with the Livestock Protection Program.
Beginning with the developing pattern of urban and suburban coyotes attacking humans in southern California in the late 1970s, we have gathered information on such incidents in an effort to better understand the causes of such changes in coyote behavior, as well as to develop strategies that can reduce the incidence of such attacks. Here, we update information from our knowledge of conflicts between humans and coyotes occurring largely in urban and suburban environments in the United States and Canada during the past 30 years. This problem emerged in states beyond California and in Canadian provinces in the 1990s, and it appears to be growing. We have documented 367 attacks on humans by coyotes from 1977 through 2015, of which 165 occurred in California. Of 348 total victims of coyote attack, 209 (60%) were adults, and 139 (40%) were children (age ≤10 years). Children (especially toddlers) are at greater risk of serious injury. Attacks demonstrate a seasonal pattern, with more occurring during the coyote breeding and pup-rearing season (March through August) than September through February. We reiterate management recommendations that, when enacted, have been demonstrated to effectively reduce risk of coyote attack in urban and suburban environments, and we note limitations of non-injurious hazing programs. We note an apparent growing incidence of coyote attack on pets, an issue that we believe will drive coyote management policy at the local and state levels.
Documented coyote attacks on humans are rare events distributed throughout North America. Geospatial monitoring and categorization of coyote behavior type provides essential information necessary for the focused management of coyotes that pose a risk to human safety. Indices of behavior have been used to measure trends in observed behavior with respect to management effort over time. A method is presented for evaluating coyote behavior density for use in developing a human dimension-based decision model with management implementation thresholds. The proposed model allows for the geo-specific adaptive management of coyotes while considering potential environmental, ecological, and social impacts in the course of protecting human safety.
Behind dire wolves and saber-toothed cats, coyotes rank as the third most commonly found mammal in the La Brea Tar Pits proving they have been residents of Los Angeles County for thousands of years. There has probably always been some degree of human-coyote conflict, but to many current residents, the situation seems to be getting worse. The Los Angeles County Department of Agricultural Commissioner/Weights and Measures is one of the last public agencies in the County attempting to manage coyotes in certain situations, which is proving to be challenging, given the changing nature of public opinion on coyote control issues and the public’s general knowledge of wildlife. I discuss how the Los Angeles County, Department of Agricultural Commissioner/Weights and Measures attempts to meet the expectations of the public in the light of these changing attitudes.
An Examination of Citizen-Provided Coyote Reports: Temporal and Spatial Patterns and Their Implications for Management of Human-Coyote Conflicts
In many cities across the United States, incidences of coyote encounters (Canis latrans) and human-coyote conflicts are rising. This is especially true for cities in Southern California, where conflicts including pet attacks have been recorded since the 1960s. The only coyote-related human fatality in the United States occurred in Southern California in 1981 and, although no fatal attacks have occurred since, coyote bites to humans are still occurring. Coyote attacks on pets appear to be common in Southern California; however, data are lacking in this area of human-coyote conflicts. This paper examines data from multiple sources that record human-coyote conflicts in Southern California. Coyote reports have been more frequently received by the entities involved in this analysis as their recording time progresses, with data from 243 cities and unincorporated areas suggesting that the majority of reports (68%) are related to non-conflict events. Conflicts were significantly higher in the pup-rearing season compared to the breeding season. There appears to be spatial clustering of coyote reports from Los Angeles County; however, complex analysis is needed to determine the relationship between frequency of complaints and land use in all of the counties to help determine what is driving human-coyote conflicts in Southern California.
Using Coyote Hazing at the Community Level to Change Coyote Behavior and Reduce Human-Coyote Conflict in Urban Environments
The concept of hazing (aversive conditioning) is often promoted as a tool for reducing human-coyote conflict in urban environments. Little scientific evidence exists on the effectiveness of hazing, particularly hazing applied by residents (i.e., community-level hazing). Many wildlife professionals question if residents will properly and consistently apply hazing techniques and if hazing impacts coyote behavior over short- and long-term periods. We describe two efforts in the Denver Metro Area (a citizen science program and an open space experiment) in which we evaluate community-level hazing in the short term. We designed both efforts to engage residents in the issue of human-coyote conflict and encouraged them to apply hazing techniques on coyotes. For our citizen science program, we offered 15 classes between October 2012 and December 2013 and trained 207 volunteers to haze coyotes and to gauge the coyotes’ short-term response to hazing. From 8/26/2012 to 12/26/2015, citizen scientists recorded 739 coyote observations of which 96 (13%) involved hazing. The most commonly used hazing method was voice (77%), followed by noise (33%), approach (33%), and body (28%). Fifty-three percent of the time, citizen scientists combined more than one and up to four methods at a time in their hazing application. Coyote response to hazing varied from rapid fleeing of the area to approaching the person doing the hazing. In the presence of domestic dogs, hazing was less effective. For the open space experiment, we selected four urban park and open space properties (two treatments and two controls) with prior histories of coyote conflict. Here, we report only on how people responded to our educational efforts at treatment sites where we provided passive, non-personal coyote hazing education via signs, email, and social media as well as education stations staffed by volunteers. Based on survey results, 23% of people that saw a coyote tried hazing it during our study trial period. Seventy-eight percent indicated that they would haze a coyote in the future, and 75% indicated the educational effort influenced their decision to haze or not. We conclude that hazing can be a useful tool for short-term relief from a coyote encounter, but the term “hazing” is confusing for some residents. We recommend that instead of using the term “hazing” that other terms such as “scare away” be incorporated into a proactive coyote conflict management strategy. For coyotes that have become exceptionally bold and demonstrated real aggression toward humans, we do not recommend hazing as a strategy to effectively deal with these problem individuals over the long term, but instead recommend the humane removal of these animals from the population.
Human-coyote conflict in urban environments is a growing issue in cities throughout the United States with the primary problem being the development of problem individuals that are overly bold and aggressive with people and pets. Little research has focused on management options to deal with this conflict. We better define lethal and non-lethal management strategies associated with proactive and reactive management of coyotes, with an emphasis on management of problem individuals. We then provide data from research in the Denver Metropolitan Area (DMA) that focused on reactive lethal removal of problem coyotes and reactive non-lethal hazing (i.e., community-level hazing). The primary lethal management strategy being used in the DMA is to remove problem coyotes only when severe conflict (primarily threats to people) occurs. From 2009-2014, there were 27 removal events (4.5/year) with the average number of coyotes removed per event being 2.1 (range 1-11) and the average number of coyotes removed per year being 9.3. The estimated percentage of coyotes removed per year from the population was between 1.0 and 1.8%. We also measured recurrence of conflict (i.e., length of time until another severe conflict occurred in the vicinity of a removal event) as a measure of efficacy. Of the 27 removals, there were nine with recurrence with an average of 245 days (range 30-546) between removals, and 18 events without recurrence and with a mean time since conflict event of 1,042 days (range 1332,159). For our community-level hazing experiment, we used wildlife cameras to record activity of both people and coyotes at four sites (two treatment and two control). At treatment sites with prior history of conflict, we educated and encouraged people to haze visible coyotes and hypothesized that hazing would decrease the activity overlap between people and coyotes on treatment sites. We recorded over 50,000 independent sightings of people and coyotes and found activity overlap between humans and coyotes to be either similar or greater on treatment sites compared to control sites. Our results indicate that reactive non-lethal hazing as conducted in this study was ineffective. However, due to a variety of reasons we detail below, we encourage readers to interpret the hazing results with caution. We conclude that reactive lethal removal of problem individuals is an effective means of managing conflict. We also maintain that proactive non-lethal strategies are critical and justify both conclusions.
Interest groups are lobbying local authorities nationwide to manage the increasingly dangerous problem of nuisance urban-coyotes by adopting a so-called “hazing” regime, whereby the populace is educated to actively engage coyotes with hostile actions, such as yelling and throwing objects at them. While there is some scientific basis for including an organized hazing regime as one component of a comprehensive urban-coyote management plan, these interest groups have been successful in convincing many local authorities that a public hazing regime is, aside from removing attractants, the only acceptable approach for addressing aggressive or habituated coyotes and that any lethal measures are not only inhumane but ineffective, as a matter of science. However, there is no mainstream scientific literature that supports their view. To the contrary, the only scientific literature on the subject casts doubt on the efficacy of hazing, at least as a long-term solution. Nevertheless, many municipalities have accepted these objectively biased groups’ representations as scientifically valid with little question and have adopted coyote policies based on such representations, without the usual hyper concern for public safety and liability that municipalities are famous for. This paper puts the urban-coyote management plans pushed by interest groups, like the Humane Society of the United States and Project Coyote, under the microscope to evaluate their scientific pedigree to show how widespread their campaign of misinformation reaches.
Food Habits and Anthropogenic Supplementation in the Diet of Coyotes (Canis latrans) along an Urban-Rural Gradient
Coyotes are recent colonists of the Southeast and have broadened their niche to include exploitation of urban areas. The aim of this study was to examine diet of coyotes inhabiting areas of differential development by humans and assess prevalence of anthropogenic feeding, to detect a possible shift in dietary trends. In urban, exurban, and rural areas of east-central Alabama, 159 fecal samples were collected and examined to reconstruct the diet. Consumption of anthropogenic food did not vary significantly along an urban-rural gradient and foods consumed were similar among habitats. While results of this study can provide insight to guide decisions about managing populations of urban-exurban coyotes in the Southeast, further research should be conducted in a diversity of developed areas to assist wildlife managers in evaluating strategies for managing populations of urban-exurban coyotes.
Grappling with Wild Pigs in California High Country: Wild Pig Population and Disturbance Research at Tejon Ranch
Wild pigs cause extensive damage to ecological resources, agricultural lands, and private property, and carry diseases that may pose a health risk to livestock and humans. At the Tejon Ranch in the Tehachapi Mountains of California, a population of wild pigs produce extensive ecological and economic damages, and share rangelands with cattle. Via the Tejon Ranch Conservation and Land Use Agreement, the Tejon Ranch Conservancy is charged with the science-based stewardship of over 970 km2 of conserved lands at Tejon Ranch. During the summer of 2014 we initiated pilot field research to develop monitoring and control methodologies to better manage wild pigs and associated disturbance across Tejon Ranch’s conserved lands. We compared line transect surveys (LTS) with remotely triggered wildlife trap-cameras as alternative methods to estimate pig abundance. Density estimates were made from LTS survey results using program DISTANCE, while indices of abundance were developed from camera trap data. We also estimated ecological disturbance by measuring the amount of pig rooting along segments of LTS transects. Wetland areas, along with higher elevation interior habitats received more damage than dryer, lower elevation habitats, which was expected given our summer surveys. Expanding on these pilot abundance surveys, we are now attempting to achieve more precise population density estimates using mark-resight techniques through a combination of trapping and collaring animals as well as individually identifying pigs from their unique pelage patterns.
Feral swine are a serious management issue for natural resource managers, farmers, ranchers, and increasingly even suburban, private property owners. The 270,000-acre privately-owned Tejon Ranch in the Tehachapi Mountains of California, the subject of an historic conservation and land use agreement that conserved 90% of the property, supports a population of feral pigs that originally escaped from a private hunting ranch in the Tehachapi. Pigs now established on Tejon Ranch produce extensive ecological and economic damages, but are also a revenue source for the landowner’s hunting program. The Tejon Ranch Conservancy serves as steward of the conserved lands and is evaluating management options to reduce feral pig damages, while respecting the landowner’s right to maintain a hunting operation. To inform our management, we have modeled pig population responses to age- and sex-specific harvest scenarios. Consistent with previous studies, our models show that >70% of the population must be harvested annually to maintain or reduce the population, and that high harvest of adult females and juveniles is most effective at reducing abundance. Our analysis shows that population growth rates, which dictate harvest rates required for population control, are most sensitive to reproductive rates, and we have no site-specific data to estimate reproductive or mortality rates. As part of the National Feral Swine Damage Management Program, the Conservancy is partnering with the USDA Animal Plant Health Inspection Service on a research and monitoring project to estimate feral pig population size and demography; habitat use and home ranges; and damages at Tejon Ranch. The ultimate objective of the program is to evaluate techniques for reducing damages cause by feral swine.
Feral swine are an invasive species within the U.S. and cause millions of dollars in damage annually. The management of feral swine may contrast with traditional wildlife management objectives and provides an opportunity to review wildlife damage management in a new context. The authors examine feral swine damage management in the context of the North American Model for Wildlife Management and note where feral swine management departs from traditional management. While wildlife management agencies are actively engaged in feral swine management and control, the traditional approach will need to be modified to prevent populations from spreading. A model feral swine management program is presented for consideration.
We report the results of one of the most comprehensive surveys on feral swine damage and control in 11 U.S. states (Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, Missouri, North Carolina, South Carolina, and Texas). The survey was distributed by the USDA National Agricultural Statistical Service in the summer of 2015 to a sample of producers of corn, soybeans, wheat, rice, peanuts, and sorghum in the 11 states listed above. A total of 4,377 responses were obtained. Findings indicate that damage caused by feral swine can be substantial. The highest yield loss estimates occur in peanut and corn production in the Southeast U.S. and Texas. We hope findings from this survey will help guide control efforts and research, as well as serve as a benchmark against which the effectiveness of future control efforts can be measured.
State officials first discovered free-roaming feral swine breeding in New York from 2000-2005. Escapes from highfence shooting facilities and Eurasian wild boar breeding operations, as well as intentional releases to create new hunting opportunities, allowed these animals to become established in four distinct populations. Utilizing a strategy of “whole sounder” management, in which entire family groups of swine are captured all at once, USDA APHIS, Wildlife Services and the New York State Department of Environmental Conservation removed 209 feral swine from 2008-2014. It appears that feral swine populations were eliminated from New York, as there have been no confirmed sightings since October 2014. Wildlife Services is leading a multi-faceted monitoring effort that includes the use of trail cameras, aerial surveys, detection dog surveys, and the development of an early detection network to reduce the risk of a reinvasion caused by failure to detect the last remaining individuals. Additionally, New York addressed the problem at its roots by passing legislation that prohibits hunting, propagation, trade, and possession of Eurasian wild boars and Eurasian wild boar hybrids. Much of the state’s feral swine elimination program success is attributed to lessons learned from successes and failures of past and ongoing wild pig elimination campaigns around the world. New York encountered unique challenges requiring innovative solutions that are informative to future invasive species eradication efforts. We provide an overview of the New York efforts to eliminate feral swine with an emphasis on education/outreach, regulatory action, lethal control, and monitoring.
Until 2006, San Diego County remained one of two counties in California that did not have a resident population of non-native wild pigs. Since that time, three or more introductions of pigs resulted in the establishment of several populations of wild pigs that grew and were believed to span the backcountry of San Diego County. Feral pigs have the potential to harm sensitive habitats, compete with native species, negatively impact drinking water quality, damage agriculture and rangelands, destroy archeological sites, and transmit diseases. They also pose a significant threat to the network of protected areas in San Diego County. In 2009, affected public land management agencies began working together to address San Diego’s pig problem in an alllands approach by forming an Intergovernmental Pig Group. The Group determined that eradicating pigs was feasible, especially given recent drought conditions, and should be the ultimate goal of the project. In the summer of 2014, USDA APHIS Wildlife Services began a large-scale effort to remove pigs across San Diego County. We provide an update on the status of the eradication effort and share information we have gathered on the San Diego pig population from remote cameras and samples collected from pigs taken during this effort. We also outline our strategy for the future to achieve eradication, including how an independent monitoring study will be used to certify that eradication has been, and remains, successful.
A Comprehensive Nine-Year Case History of Texas A&M AgriLife Extension’s Educational Impacts on Wild Pig Damage Abatement in Texas
Texas has the largest wild pig population in the nation, estimated at 2.6 million animals. Damage to agronomic enterprises was conservatively estimated in 2004 at $52 million annually with total economic damage to agriculture and the environment in urban, suburban, and rural Texas possibly reaching 10 times that figure. In response to damage caused by this invasive exotic species, the Texas A&M AgriLife Extension Service increased educational programming efforts of wild pigs and damage abatement. From 2006-2014, project funding from multiple sources facilitated the development and deployment of Texas A&M AgriLife Extension Service-led landowner education via one-on-one contacts, group meetings, demonstrations, and publications. Website availability and mass media contacts, including television and radio interviews and newspaper and magazine articles, were also utilized to increase public awareness and education on wild pigs and damage abatement. Participants (n = 21,752) attending Extension educational events were surveyed (n = 13,054) to characterize damage and control efforts as well as measure the impacts of education efforts. The most commonly reported negative impacts by landowners were pastures/hay meadows (72%) and owner/employee time (38%), while the most commonly used control technique prior to participation in an educational event was trap and destroy (51%). The average amount of losses attributable to wild pigs in the year prior to attending an educational program was $4,764 each and their predicted loss after participation decreased to $3,565. Over 98% of respondents indicated they increased their knowledge of wild pigs and damage abatement and planned to adopt an average of three new management practices each, with the most commonly cited new practices being using larger traps and pre-baiting wild pigs. A Net Promoter Score of 60.4% indicated that survey respondents were very pleased with the information they received by attending an Extension educational event directed at wild pigs and the abatement of their damage. This educational model can serve as a template for other states dealing with wild pigs as an emerging issue whenever their negative impacts on agriculture, the environment, and human health and safety occur.
Wild pigs, present in over 140 (of 159) counties in Georgia, cause significant problems. They are hunted and trapped for recreation, yet they are responsible for over $150 million in damage to property and crops. Research suggests that the public has divergent approaches to wild pig control, lacks knowledge about effective control strategies, undertakes a range of legal and non-legal control activities, and suffers significant financial losses from wild pigs. Not all landowners experience similar amounts of damage and therefore attitudes regarding the significance of the wild pig problem in Georgia differ widely among citizens. Respondents from a previous wild pig survey in Georgia (farmers in ¼ of the state) felt most control measures were ineffective and that state and federal agencies should provide more assistance. Previous respondents perceived a decline in some native game species and blamed wild pigs. I conducted a statewide survey of 3,000 landowners in February 2015 to assess broader perceptions towards wild pigs, estimate economic losses from wild pig damage, and determine attitudes toward wild pigs. Overall response rate was 38% (n = 1,109). Analysis suggests that farmers have more direct contact than other landowners with wild pigs and therefore shoulder more of the costs related to damage (e.g., crop loss, food plot, and timber damage). Statewide, respondents favor measures to reduce wild pig populations. Respondents believe wild pig populations are increasing due to lack of hunting, natural reproductive potential, and illegal trap and transfer. Generally, respondents felt that self-implemented lethal control measures were not effective at reducing wild pig populations or damage.
Although national surveillance is conducted throughout the United States for multiple pathogens associated with feral swine, many pathogens that persist in wild pigs globally have not been the subject of investigations within the U.S. We surveyed feral swine in Florida for two viruses that are ubiquitous in domestic and wild pigs in Europe: torque teno sus virus type 1 and porcine lymphotropic herpesvirus. We found these viruses to be prevalent in feral swine in Florida. We detected viral DNA in nasal and genital swabs or whole blood collected from animals at multiple locations throughout the state. Our results suggest that not only are animals infected with these viruses, but that they are actively shedding virus and capable of transmitting them at multiple, geographically disparate locations. These viruses have the potential to be pathogenic when an animal is coinfected with other porcine viruses, and these viruses pose a potential threat to other wildlife, livestock, and people.
Registration of a new toxicant for feral swine in the United States requires meeting test standards under the Federal Insecticide, Fungicide, and Rodenticide Act as regulated by the U.S. Environmental Protection Agency. A primary requirement is to compare the palatability and efficacy of the toxicant to a non-toxic challenge diet in a 2-choice test; however, no standardized challenge diet exists for feral swine. We conducted a series of 2-choice tests to examine four potential challenge diet items for preference by feral swine. We found that feral swine consumed the most and spent the most time feeding on rough rice (i.e., seed rice), although dog food and rough rye could not be wholly discounted as potential challenge diets. Rough rice was preferred, provided adequate nourishment, and is readily consumed by free-ranging feral swine. Therefore, we conclude that rough rice is an appropriate challenge diet for incorporating into 2-choice tests to meet test standards for evaluating the effectiveness of an oral toxicant for feral swine.
Feral hogs are known to be expanding their range in Brazil since late 1980s and reports of damage to crops and livestock predation have become more frequent lately. Just recently, the use of lethal methods for feral hog control was legalized in Brazil, and there are still several restrictions, particularly towards the purchase and transportation of guns and ammunition. Results of questionnaires from feral hog hunters showed that around half of them still act illegally, and hunting with dogs was the main technique used for controlling feral hogs. We believe that to enhance feral hog control in Brazil, legislation needs to be reviewed, and a national control program needs to be created involving researchers, government agencies, and hunters, working together on development and implementation of more efficient techniques for feral hog population control.
Feral swine in the United States are known to harbor both native and exotic Ixodid ticks. The expanding range, broad habitat use, high population potential, and large movements of feral swine may increase the distribution and density of certain tick species and tick-borne pathogens that can infect humans, livestock, and wildlife. This preliminary study was conducted to determine which tick species are present on feral swine as well as other mammals sympatric with feral swine in south-central Florida. We trapped large-, medium-, and small-bodied mammals at two study sites, Kissimmee Prairie Preserve State Park and MacArthur Agro-ecology Research Center, from February to May of 2014. We examined mammals for ticks and conducted drags for host-seeking ticks. We trapped five mammal species (feral swine, Florida mouse, marsh rice rat, Virginia opossum, and northern raccoon). From these animals we identified four native tick species (Amblyomma americanum, A. maculatum, Dermacentor variabilis, and Ixodes scapularis) and one exotic to the United States (A. auricularium). We also obtained carcasses of nine-banded armadillos in Brevard County, on which we found A. auricularium. This is the first report of I. scapularis in Okeechobee County and A. auricularium in Brevard and Highlands Counties. All four native tick species are known disease vectors. These data reiterate that many mammals that share habitat with livestock and commonly contact humans are hosts to many ticks of medical and veterinary importance. Coupled with the population, distribution potential, and movement of feral swine, the diversity of ticks found in this study highlights the need for further research on the ability of feral swine to host and distribute ticks and tick-borne pathogens among wildlife, livestock, and humans.
Feral hog population has been increasing significantly in the past few years in Brazil. Rio Grande do Sul state has the largest sheep herd in Brazil and predation reports had grown exponentially lately. In Santana do Livramento County, 20,000 lambs were reported predated by feral hogs in 2013, resulting on approximately US$700,000 direct losses. Rising domestic pigs free-ranging is still a common practice, which increases the opportunity for breeding and hybridizing with the feral population, resulting in better environmental adaptation and reproductive ability of the offspring. American literature suggests that females can produce 1.6 litters per year with an average of 5.7 piglets per litter. However, reports from feral hog controllers in Santana do Livramento, in the Campos grasslands with short riparian forest, suggest a higher reproduction rate, where pregnant females carry from 3 to 14 fetus, averaging 7.5 piglets per litter (n = 61). According to simulation from data collected in Southern Brazil, feral hog populations could be increasing at a rate of 36% higher than what thought before. Survival rates also seem to be high, with repots of up to 12 piglets per litter at weaning age. This could be attributed to favorable climatic conditions and resources abundance (i.e. water and feed). Data from camera-traps in Itamonte County, Minas Gerais State, identified females farrowing once per year with an average of 2.3±1.6 piglets (n = 55) in continuous fragments of Brazilian Atlantic Forest. The Araucaria angustifolia seeds and local small crops are known to be important resources for feral hog population. Those are preliminary data of investigation being done in Brazil, and several more questions need to be assessed. An estimation of economic losses and potential of population expansion need to be done in both south and southeast of Brazil, where the feral hog invasion are concentrated. Those are key information for warning competent attorneys to the problem and to start a broader and more effective control planning.
Economic impacts, risk factors, and deterrent strategies related to fruit damage by birds were investigated in a four year study across North America. Here we focus primarily on bird management strategies tested in the Pacific Northwest, including visual deterrents such as hawk-kites, inflatable tube-men, and falconry. Fields protected by professional bird-abatement falconry showed less blueberry damage than non-falconry fields. Neither hawk kites nor kite-falconry combinations showed strong damage prevention. A pilot trial of inflatable tube-men in blueberries showed a potential deterrent effect in one of three blocks. Bird management strategies that are biodiversity-friendly, such as falconry and predator nest boxes, may also be useful in marketing fruit.
Insect Pest Control and Bird Damage as a Function of Distance from Riparian Habitat in a California Vineyard
Farmers have few tools with which to objectively assess the true impact of avian species on crop production, partly because ecologists and conservationists have been slow to quantify the role of birds within agricultural settings. At an annual value of over $5.5 billion dollars, vineyards are the third-most-valuable agricultural crop produced in California. Vineyard area has rapidly expanded in California and now covers at least 820,000 acres. Encouraging growers to retain existing natural habitat around vineyards or install new habitat, such as hedgerows, is likely to have positive effects on biodiversity. However, viticulturists are often wary of actions that could increase wildlife numbers on their land, particularly birds, since they are considered one of the most damaging pests to vineyards worldwide. In California, over 67% of vineyard acres have some degree of bird damage, with estimates ranging from between 5.4% and 16.1% of crops damaged. Conversely, birds may provide vineyards with valuable pest control services by consuming insects in high numbers in the spring and summer. Quantifying these costs (bird damage) and benefits (insect pest control) for vineyards from birds as they relate to natural habitat is an essential step in understanding the net value of nature in vineyard ecosystems. In July 2015, I used a sentinel prey experiment in a California vineyard to measure the relationship between insect pest-control, bird damage, and distance from a riparian corridor. I found that over 40% of sentinel prey were consumed at the edge of the vineyard, and that birds damaged 12% of grapes. Depredation of sentinel prey and grape damage dropped at a similar rate with increasing distance from riparian habitat. These results suggest that birds may remove insect pests at a rate that could offset the damage caused by avian foraging once grapes are ripe, but further studies are needed to confirm this.
Some species of birds form large flocks that forage on agricultural fields and frequently damage the crop, resulting in significant economic losses. Additionally, by defecating they potentially contaminate the crop and farm equipment with pathogens, which is of special concern for leafy greens that are consumed uncooked. There is a need to find an effective deterrent that is also environmentally friendly, and falconry is an ideal candidate for this purpose. To evaluate falconry as deterrent of nuisance birds in leafy greens field in northern California, we performed a set of trials on a control ranch and a treatment ranch of similar production and landscape characteristics. We identified avian species, counted individuals, and recorded flock size in daily surveys pre-treatment, during treatment (falconry), and post-treatment. Bird abundance was lower in spring than in fall, probably because many fields were fallow in spring. In both seasons, we observed a large daily variation in the bird abundance and their use of the fields in the surveys pre-treatment. In fall, the first trial was interfered by the activity of a falconer in an adjacent vineyard and the harvest of the grapes. Importantly, in the second trial, use of the field (e.g., foraging, etc.) decreased during five days of treatment and continued to be low for three days post-treatment, suggesting a “memory effect” after hazing by falconry. Interestingly, the third fall trial coincided with the end of the leafy greens growing season and showed that falconry successfully minimized use of the field by nuisance birds during peak activity. These results indicate that falconry is an effective measure to protect leafy green crops from fecal contamination and damage, but further research is needed at more farms in different regions, and the effect of using falconry in combination with other non-lethal bird abatement approaches (e.g., audio-visual deterrents) should also be evaluated.
The purpose of this study was to gather information on the feral pigeon population living in the central business district (CBD) of Butte, MT. Pigeons in the CBD have historically been part of the urban landscape and have contributed to local biodiversity. We report on an aspect of a larger study that was initiated to address complaints from business owners concerning damage caused by pigeons. To better understand feral pigeon population dynamics, we used live trapping, marking with leg bands, and survey transects to study the pigeons’ distribution, habitat selection, and dispersal. Our results thus far indicate minimal dispersal between colonies. Two individuals have shown dispersal movements of up to 6.1 km from the tagging site. Transect surveys revealed an average of 173.3 birds present, with a maximum count of 254 and minimum of 101.
Blackbirds are reported to cause between 1-2% crop damage per year, but the distribution of damage is not uniform, with some fields this number can be as high as 20%. With many consumers in today’s market concerned with animal welfare, nonlethal management techniques have become more important. Many of these techniques exploit natural predator-prey systems. One area of research that has not been previously addressed is the physiological response of birds to visual and auditory scare devices designed to imitate predators. The current project is part of a series of studies that aim to develop knowledge of both physiological and behavioral trade-offs of female red-winged blackbirds when exposed to predation risk as a chronic stressor. Breeding colonies were exposed to an avian predator, avian nest parasite, or a non-threatening avian effigy with corresponding bird call at the beginning of the breeding season. Behavioral responses were monitored across the season, including general response to the predators and reproductive trade-offs. We predicted that female response to perceived predation risk would be greater than response to parasites or control treatments, and that females would make a greater reproductive trade-off in favor of future breeding seasons when presented with the perceived risk and stress of predation. Results suggest that red-winged blackbirds do have a greater response to the perceived risk of predation than to the parasites or control treatments. In terms of nest success and lay date, females do not seem to have different reproductive behavioral trade-offs under different treatments. However, there is a trend for larger clutches in nests found within the predator treatment, suggesting that females may actually be making a trade-off for the current rather than future seasons. Future work will focus on analyzing the physiological trade-offs that females make during the breeding season, especially while under chronic stress of predation risk. Results will help provide a basis for applied research aimed at improving bird damage management.
We studied the causes of mortality for the California Ridgway’s rail at multiple tidal marshes in the San Francisco Bay Estuary, California. We radio-marked 196 individual rails and examined the evidence from 152 recovered California Ridgway’s rail mortalities from our radio-marked sample and determined plausible cause of death from a wide array of evidence. We also included 10 additional California Ridgway’s rail mortalities (unmarked) that we encountered during our normal field operations. We assigned a likely cause of death to 130 of the recoveries, of which 127 were determined to be caused by predation. Of those, 103 could be divided into class of cause (avian or mammalian), and avian predators were responsible for 64% of those events. Primary predators identified include domestic or feral cats, red fox, owl, and northern harrier. We did find seasonal differences between avian and mammalian predation rates, with higher proportions of avian predation in the winter and early spring. Time of day and tide height were correlated with predation events, with a greater proportion of known mortalities found during periods of high tides (over 60% marsh inundation) and during daylight hours. Predation is the primary source of mortality for California Ridgway’s rail. Management actions that try to reduce avian predation may be the most effective at improving rail survival rates, given the proportion of avian predation detected.
Nest predation is pervasive and debatably the most vital factor limiting avian productivity. Studies have shown that avian and mammalian predator control programs for the protection of shorebirds have been successful in increasing overall nesting success. Our work focused on the management of both native and non-native predator populations at Naval Base Coronado (NBC) in an effort to minimize predation pressure upon the California least tern and western snowy plover populations during the breeding season. We had a total of 580 tern and plover egg and non-egg predation events on NBC between 2012 and 2015. Predation by corvids was responsible for 63% of total predations, raptors 24%, mammals 7%, and other animals 6%. We captured 60% (n = 93) of the corvids with modified goshawk traps and 90% (n = 17) of the raptors with Bal-chatri traps. Our predator management program focused on the control of corvids, rather than mammals and raptors, as corvids were historically responsible for the greatest loss of tern nests compared to other taxa. We used a variety of trapping and hunting techniques over the years and, through trial and error, have enhanced our removal success and overall predator management program on Naval Base Coronado.
The USDA APHIS WS Unified Model for Estimating DRC-1339 Bait Application Take Estimates as Effected by French Fry Bait Size
DRC-1339 (CPTH, 3-chloro-p-tolouidine) is an avicide registered to reduce local populations of selected bird species at feedlots, dairies, and staging areas near rice fields, and to prevent livestock depredation. Additionally, two registrations are specifically for controlling gulls and pigeons. U.S. Department of Agriculture Wildlife Services personnel historically have used a variety of methods to estimate take, including counting carcasses and quantifying reduction in bird activity. Because this avicide is slow-acting and birds usually succumb away from the bait site, carcass recovery provides poor estimates of take. Because of natural variability in bird numbers and activity, quantifying reductions in bird activity is also a poor gauge of efficacy. Scientists at the U.S. Department of Agriculture APHIS Wildlife Services National Wildlife Research Center developed and continue to adapt and refine a model using a bioenergetics approach to estimate consumption and the resulting mortality from DRC-1339 bait consumption. The model estimates take for the major baits used under the feedlot and staging area labels for European starlings, blackbirds, brown-headed cowbirds, and common grackles. Consumption of homogeneous baits (rice, cracked corn, fat pellets) has been well characterized, and take (i.e., mortality) is accurately predicted in the model. However, predictions of take when french fries were used as a bait for controlling starlings at feedlots in Washington State were less accurate. Thus, we modified the model to capture the feeding behavior of birds using this highly heterogeneous bait by removing the dependence on bait mass and simplifying the calculation of dose ingested. The modified model calculates dose directly from the amount of DRC-1339 per calorie consumed instead of from the DRC-1339 concentration per bait consumed. In this paper, we compare estimates of take based on french fry bait mass distributions and caloric contents determined for five different french fry bait types.
Raptor-aircraft collisions (bird strikes) pose a serious safety risk to civil aircraft. Even smaller raptors, such as American kestrels, can be problematic within many airport environments. Given public interest, logistical and financial constraints, and other factors, managing raptors at airports presents some unique challenges. Although a variety of damage reduction methods are often used, non-lethal tools are typically favored by the public. Like many airports, American kestrels are commonly struck at the Los Angeles International Airport (LAX). Wildlife mitigation efforts at LAX (primarily live-capture and translocation away from the airport) were directed toward reducing the presence of kestrels. Management actions (e.g., pesticide applications) to reduce the availability of grasshoppers on the airfield at LAX were unsuccessful. On-airfield monitoring of American kestrel abundance was correlated (r = 0.84, p = 0.003) with the annual rate of kestrel-aircraft collisions at LAX, demonstrating the importance of continuing efforts to monitor populations of hazardous wildlife. Although an integrated wildlife damage management program is used at LAX, the extensive use of non-lethal methods (i.e., live-capture and translocation) to reduce the abundance of American kestrels at LAX appears to be an important part of that program.
Managing Raptor-Aircraft Collisions on a Grand Scale: Summary of a Wildlife Services Raptor Relocation Program
Bird-aircraft collisions (bird strikes) pose a serious safety risk to aircraft. Raptors (i.e., hawks and owls) are one of the most frequently struck guild of birds within North America. Integrated wildlife damage management programs combine a variety of non-lethal and lethal management tools to reduce the presence and duration of raptors at airports. Live-capture and translocation away from an airport is a commonly used method to reduce the risk of raptor-aircraft collisions. In 2007, USDA APHIS Wildlife Services (WS) developed an airport program-specific plastic leg band (i.e., black with yellow alpha-numerics) for use in operational raptor management activities by the agency at airports. As part of this nation-wide effort, WS airport biologists live-captured, marked with auxiliary markers (i.e., project-specific leg band), and conducted over 3,900 raptor translocations from airports and military bases located in 16 states during January 2008-May, 2015. This represents a large portion of the raptors that were managed using this non-lethal method by WS during these years. Not unexpectedly, raptor translocation efforts and the raptor species managed varied among geographic regions/states and at specific airport locations due to a variety of logistical factors. Fifteen different raptor species were marked and translocated during this effort. Red-tailed hawks, American kestrels, and great horned owls accounted for 58%, 14%, and 6% of marked/translocated birds, respectively. Although research is needed to better understand and increase the efficacy of such management efforts, this non-lethal method of reducing the presence of individual raptors at airports will be an important component of future wildlife damage mitigation programs.
Behavioral Responses of Red-winged Blackbirds to Simulated Predators: Evidence of Potential Habituation to Video Stimuli
Wildlife damage to crops has a significant impact on crop productivity, and mitigating the impacts of damage requires managers to employ multiple and creative solutions. The development of Unmanned Aerial Systems (UAS, drones) provides a new tool that may be effective in managing bird damage to crops. We used multisensory video/audio playback to assess the behavioral responses of red-winged blackbirds (RWBL) to videos of UAS. Captive birds were individually exposed to movies comprised of five video clips that varied in stimulus content on two occasions. Video stimuli included a known predator, UAS, and avian controls (birds that are not predators of RWBL). Although all test birds interacted with the movies, not all displayed the behaviors that were measured. Of those that did display the behaviors measured, responses to most video stimuli were reduced during the second trial compared to the first. These findings suggest that blackbirds are responding to videos; however, they habituate to video stimuli perceived as a non-threat and adjust their behavioral responses accordingly.
Pathogen Risks Related to the Movement of Birds Frequenting Livestock and Fresh Produce Growing Areas in the Southwestern U.S.
Concentrated animal feeding operations (CAFOs) are sometimes located in close proximity to fresh produce fields, both of which serve as easily accessible food and water sources for wild birds. When birds travel between these two areas, they have the potential to transfer pathogens from cattle, a documented source of enteric zoonotic foodborne pathogens, to fresh produce crops through fecal deposition. However, the presence of pathogens in wild birds is not a risk unless the birds or their fecal material come into contact with fresh produce crops. Therefore, the objective of this study was to determine if birds visiting CAFOs use flyways that cross fresh produce fields, thereby increasing the risk for contaminating fresh produce intended for human consumption. During 2014, birds trapped at a CAFO in southern Arizona were fitted with Lotek nano-coded radiotransmitters. Two receivers were placed at the CAFO and two receivers were placed in nearby fresh produce fields. A total of 103 birds were fitted with radiotransmitters, including 66 red-winged blackbirds, 21 Eurasian collared doves, 11 brown-headed cowbirds, four common ravens, and one European starling. Over four million data points were collected indicating the date, time, and bird ID number for each time a bird was recorded within 1 km of a receiver. Radiotelemetry results showed that birds travel regularly between the CAFO and fresh produce fields. Using PCR and culture techniques, 2 (1.9%) birds tested positive for Salmonella, and 5 (4.9%) tested positive for non-O157 Shiga toxin-producing Escherichia coli (STEC). During the same time period, Salmonella (4%), STEC O157 (16%), and non-O157 STEC (44.5%) were detected in 400 cattle fecal samples from the CAFO. Our results will aid in determining the pathogen risks that birds pose to fresh produce when they are frequent visitors to a CAFO and fresh produce fields.
This one-year study focused on the impact of hedgerows of native California plants on rodents and food safety in adjacent crops in the Sacramento Valley. Deer mice, house mice, California voles, and western harvest mice were live trapped in four different walnut orchards at zero, 10, 75, 175-m transects from hedgerows. The abundance and richness of rodents was compared to control sites with conventionally managed field edges that were mowed or sprayed for weed control. Unique rodent capture data showed two peaks in activity: 1) in the middle of the orchard regardless of field border type, and 2) in the hedgerow across all seasons with winter being the most active overall. Fewer captures were recorded in the conventional field border, likely because they lacked vegetative structure. Deer mice were the most prevalent species captured throughout the study (>96% of unique captures). House mice and California voles were almost always found in hedgerows and not in adjacent crops. Fecal samples from captured rodents showed a low prevalence of Escherichia coli (non-O157 STEC 1.4%, n = 438; O157 STEC 0%, n = 434) and Salmonella (0.92%, n = 434). Giardia (28.6%, n = 210) and Cryptosporidium (23.8%, n = 210) were more prevalent in captured rodents, but the distribution was not affected by field-edge habitat.
Identification of Zoonotic and Vector-borne Infectious Agents Associated with Opossums (Didelphis virginiana) in Residential Neighborhoods of Orange County, California
Opossums and cat fleas have been epidemiologically linked to flea-borne rickettsial disease transmission in residential backyards of Orange County, California. In 2013, a study was initiated to better elucidate the life history of opossums and their role as vectors of disease and hosts for both internal and external parasites. The study population consisted of adult opossums collected year-round from flea-borne rickettsial disease exposure sites, and moribund opossums submitted by wildlife rehabilitators in Orange County. Carcasses were examined for ectoparasites and necropsied, which included the removal and collection of endoparasites, organ tissues, feces, and urine. Reproductive life history data suggested one brood of young per year, with an average litter size of 7 (n = 9, range 2-11). Average adult weight was 2.49 kg (range 1.30-4.41 kg). Cat fleas were present on each opossum with an average of 96 fleas per opossum (n = 82, range 2-725). Thirty of 33 cat flea pools tested PCR-positive for one of the following bacteria: Rickettsia felis (53%), R. typhi (3%), the R. felis-like organisms, Candidatus Rickettsia senegalensis (28%) and Ca. Rickettsia asemboensis (3%), or Bartonella vinsonii subsp. arupensis (1.5%). Sticktight fleas (Echidnophaga gallinacea), the only other flea detected, were present on less than 6% of opossums, and ticks were not detected on any carcasses (n = 83). Endoparasitic nematodes Cruzia americana and Physaloptera turgida were present in each stomach and cecum, and Didelphostrongylus hayesior or Heterstongylus heterostrongylus was noted in lung samples of opossums (n = 83). Salmonella spp. were detected in 52% of fecal samples (n = 50), with subsequent typing of strains indicating the presence of human pathogens in all but three of the samples (n = 26). Blood and spleen samples were negative for Bartonella spp., Brucella spp., and Yersinia pestis (n = 33). Sera were negative for Leptospira-specific antibodies and Leptospira DNA was not detected in urine (n = 83). Results from this multi-agency study show that the presence of opossums in the backyard environment put Orange County residents and their pets at risk of flea-borne bartonella and rickettsial diseases and salmonellosis.
In 2006, flea-borne rickettsiosis (flea-borne typhus), a zoonotic disease caused by either Rickettsia typhi or R. felis and transmitted primarily by two flea species, the Oriental rat flea and the cat flea, re-emerged as an important vector-borne disease in Orange County, California. The Orange County Mosquito and Vector Control District (OC Vector Control) has investigated 142 human cases of flea-borne rickettsiosis. Results of these investigations have established a link with Rickettsia-infected cat fleas, opossums, feral cats, and disease transmission to humans; no cases have been associated with rats and their fleas. Since initiation of a Trap-Neuter-Return (TNR) Program by Orange County (OC) Animal Care in 2009, OC Vector Control has been working with OC Animal Care to minimize the potential public health risks associated with the TNR Program. Interagency discussions have led OC Animal Care to prohibit the release of TNR cats at locations with a high risk for zoonotic disease transmission to humans, such as schools, parks, and health care facilities, and also to disclose the release sites to OC Vector Control. OC Animal Care has not agreed to OC Vector Control’s request for a zoonotic disease review of its TNR Program, nor has it provided a procedural manual to verify the verbal agreements reached by the two agencies. In agreement with OC Vector Control’s concerns, an investigation in 2015 by the Orange County Grand Jury of OC Animal Care’s TNR Program recognized the Program’s potential to increase zoonotic disease transmission to the public and other wildlife. We discuss the conflicting views arising from two governmental agencies, which perceive the zoonotic diseases risk associated with a TNR program at significantly different thresholds of concern.
Vector Control Has a Role to Play in Mitigating the High Incidence of Flea-borne Typhus in Los Angeles County, California
More than 500 human cases of flea-borne typhus have been reported from Los Angeles and Orange Counties over the past 20 years. Only West Nile virus exceeds flea-borne typhus as an important vector-borne disease in these counties. Despite this, flea-borne typhus garners insignificant public attention compared to West Nile virus. In Los Angeles County alone there were 121 human cases of flea-borne typhus from 2000 to 2009, and 292 human cases from 2010 to 2015. Results from previous studies in Los Angeles and Orange Counties identified a suburban cycle of flea-borne typhus transmission involving backyard wildlife, pets, and the cat flea Ctenocephalides felis. Prior studies and recent observations in Los Angeles County showed that the flea burden of opossums and feral cats is onerously high, and the cat flea is the main vector of the pathogens (Rickettsia typhi and R. felis) responsible for human typhus. The rise of cases in recent years has been accompanied by policy changes in public and private animal control groups that manage nuisance animals in Los Angeles and Orange Counties. Instead of trapping and removing strays and supporting a policy of not feeding wild or stray animals, some governmental agencies and private organizations prefer trap, neuter, and release (TNR) programs and support rehabilitating/relocating feral animals. We believe these policy changes have contributed to the increased incidence of human typhus.
West Nile Virus Activity in a Winter Roost of American Crows (Corvus brachyrhynchos): Is Bird-to-Bird Transmission Important in Persistence and Amplification? (Abstract)
Since its emergence in North America, West Nile virus (WNV) has had a large impact on equines, humans, and wild bird communities, yet gaps remain in our understanding of how the virus persists at temperate latitudes when winter temperatures preclude virus replication and host-seeking activity by mosquito vectors. Bird-to-bird transmission at large communal American crow roosts could provide one mechanism for WNV persistence. Herein, we describe seasonal patterns of crow and Culex mosquito abundance, WNV infection rates, and the prevalence of WNV-positive fecal samples at a winter crow roost to test the hypothesis that bird-to-bird transmission allows WNV to persist at winter crow roosts. Samples were collected from large winter crow roosts in the Sacramento Valley of California from January 2013 until August 2014, encompassing two overwintering roost periods. West Nile virus RNA was detected in local crow carcasses in both summer [13/18 (72% WNV positive)] and winter [18/44 (41% WNV positive)] 2013-2014. Winter infections were unlikely to have arisen by recent bites from infected mosquitoes because Culex host-seeking activity was very low in winter and all Culex mosquitoes collected during winter months tested negative for WNV. Opportunities existed for fecal-oral transfer at the overwintering roost: most carcasses that tested positive for WNV had detectable viral RNA in both kidney and cloacal swabs, suggesting that infected crows were shedding virus in their feces, and >50% of crows at the roost were stained with feces by mid-winter. Moreover, 2.3% of fecal samples collected in late summer, when mosquitoes were active, tested positive for WNV RNA. Nevertheless, none of the 1,119 feces collected from three roosts over two winters contained detectable WNV RNA. This study provided evidence of WNV infection in overwintering American crows without mosquito vector activity, but did not elucidate a mechanism of WNV transmission during winter.
Vole populations in southern Idaho experienced a significant peak in 2009-10. Following 2010, a decline in the population was observed. However, in 2014-15, vole populations increased dramatically with more reported crop losses than in 2009-10. Reported crop losses for 2014-15 were 30% and higher. In extreme cases, producers experienced over 50% crop losses and removed fields from production. An Idaho producer tracked vole populations using a GIS/GPS mapping app and reported vole numbers of 200 and more per acre (per 0.4 ha). Increased vole populations significantly reduced yields in rangeland, alfalfa, pastures, and other agricultural crops. In addition, homeowners and gardeners experienced significant vole damage in lawns, gardens, and small acreage orchards. Hypotheses for increased vole populations include a series of mild, open winters allowing for higher winter survival rates and wet springs and falls that produced abundant vole forage and habitat. Voles have remarkable reproductive capacity, which further amplifies problems associated with these rodents. Extension educators and specialists have estimated average losses due to increased vole pressure in Idaho at 30% to 50% and higher in crops, pastures, alfalfa, and rangeland. If current climatic and management trends continue, populations may continue to increase. Knowledge and implementation of an integrated vole management program has become necessary to decrease damage to crops, pastures, lawns, and gardens. To address this significant problem, we informally tested several effective vole management methods. Information and data were collected on rodent biology and management techniques from existing literature and field observations. Voles are not a protected species in Idaho and can be legally managed on private and public lands. We have developed an integrated approach to managing these rodents through the use of monitoring for vole sign, habitat modification, protecting desirable plants, trapping and other mechanical control measures, and use of effective toxic baits. Lastly, we developed and implemented an integrated, multi-faceted vole education program for Idaho clientele that was critical to effectively manage increased vole populations.
We compared trapping vs. traditional strychnine baiting to control pocket gophers in alfalfa fields in southern Utah. Additionally, we compared trapping efficiency of three different pocket gopher traps: Macabee, Cinch, and DK-1. Baiting and trapping resulted in similar levels of pocket gopher activity and reduced pocket gopher activity in study plots (P = 0.02). When comparing the three trap types, Macabee was the most successful at trapping pocket gophers (P = 0.004). Macabee traps were also the most time-efficient (P = 0.02). Trapping success was very low; future work needs to focus on increased study plot size, trapping density, and modifying traps to improve trapping success of larger animals.
Control of invasive mammals is central to the conservation and restoration of native habitats, especially in unique and vulnerable island ecosystems. While methods for eradication of pest mammals on offshore islands are well-established, long-term suppression at mainland sites and in other locations with an extremely high risk of re-invasion remains challenging. We examined the use of CO2-powered, self-resetting traps for control of rats during a beech forest mast on the New Zealand mainland. Goodnature® A24 automatic traps installed on a 100 × 50-m grid reduced tracking indices for ship rats from 68% to 0% within a 200-ha area over a period of four months. The extent of the trapped area was then increased to 700 ha, with the resolution of the trapping grid reduced to 100 × 100 m. Tracking indices within the expanded area decreased from 44% to 0% within an additional two months. Activity of rats in a non-treatment site remained at around 70% for the duration of the project. Tracking indices for house mice decreased from 22% to 0% within four months and remained low for the duration of the project, indicating that non-targeted control of house mice was also achieved within the project area. Our results show that Goodnature® A24 self-resetting traps can successfully knock down and suppress rats from plague levels within an unprotected, mainland site.
Free Ranging Wild-Caught Norway Rats Have Reduced Fecundity after Consuming Liquid Oral Fertility Bait Containing 4-Vinylcyclohexene Diepoxide and Triptolide
Norway rats cause extensive crop loss, infrastructure damage, and are vectors for zoonotic diseases. Due to growing efficacy, environmental, and animal welfare concerns related to traditional pest management tools, it is important to find new methods for controlling commensal rodents. Fertility control is emerging as a safe, humane, and effective method of long-term pest population management. SenesTech Inc. has developed an oral, liquid fertility management bait with two active ingredients: 4-vinylcyclohexene diepoxide (VCD) and triptolide. Previously, a 95% reduction in pups was observed through three breeding rounds when wild-caught Norway rats were caged in pairs and offered this bait for 50 days. Following these results, wild-caught Norway rats (n=6 males; n=15 females per group) were placed in open arenas, offered bait (in the presence of rat chow and water) ad libitum for 56 days, and allowed to breed for four rounds. Animals were bred within their treatment paired groups (control or treatment) for the first three rounds and then treatment cross-bred during the fourth round. Through three breeding rounds, 255 pups were born to control breeding pairs, compared to 12 pups born to treated breeding pairs. In the final round, 93 pups were born to control females paired with treated males and 80 pups were born to treated females paired with control males. A significant reduction in epididymis weight, and in testis weight and volume, was observed in treated males, while ovarian weight was reduced in treated females. These results indicate that fertility was dramatically reduced in wild caught Norway rats after consuming fertility management bait. Rats voluntarily consumed the treatment bait, and this free selection is essential for future field trials where the ability of the bait to reduce wild rat populations will be assessed in agricultural and urban settings.
The Development of Semiochemical Lures for Invasive Rats: An Integrated Chemical Image and Response-Guided Approach
Olfactory lures are important tools in pest-species management, being widely used to monitor and trap populations. For vertebrates like rats, lures are most commonly foods such as peanut butter. However, these are perishable and require frequent replenishment; factors that decrease control operation efficacy and increase costs. Synthetic semiochemical-based lures might address these limitations, but their identification and use for vertebrate population management remains an underexploited opportunity. We used headspace solid-phase microextraction and gas chromatography-mass spectrometry to characterise the volatile chemical profiles of 19 food products previously presented to wild, free-ranging rats and assessed for attraction. Partial least squares regression identified 10 of the 111 compounds found in two or more analysed products to be statistically significant predictors of attraction. The identity of nine of the compounds was verified using authentic samples, while one was not commercially available. Field trials used tracking tunnels to present compounds at seven different concentrations from 10,000 ppm to 0.01 ppm. Inked cards inside tracking tunnels were used to quantify visitations using species tracking marks, with the presence of rat tracks on inked cards scored to provide a tracking rate. Five compounds outperformed peanut butter while eight individual semiochemical-based lures each statistically outperformed peanut butter. Nearly half of all confirmed visits to compounds were with lures presented at 0.1 and 0.01 ppm. A trend of increasing tracking rates with decreasing lure concentration was identified for aggregated compound data. Our results suggest a number of compounds have the potential for onward development as synthetic attractants for rats. Further, the results support our integrated chemical image and response-guided approach that statistically associated behavioural responses to a range of products with the volatile compounds in those products. This approach has the potential to identify semiochemical compounds, either allelochemical or pheromone, for use as olfactory lures for managing and monitoring a range of vertebrate pest species.
Evaluation of Forage Preferences and their Corresponding Nutritional Content for Northern Pocket Gophers (Thomomys talpoides)
Pocket gophers cause substantial damage in a number of western states. A better knowledge of their forage preferences and the nutritional attributes of those preferences could result in better management of populations and reduction of damage. We live-trapped northern pocket gophers in northern Idaho and brought them into captivity at Washington State University, Pullman, WA. We tested their preferences for several species of forbs, grasses, and woody species. Preferences varied in all plant groups. Forbs were highly preferred in early summer but dropped off in late summer, perhaps due to senescence. However, preference for woody species increased in late summer and winter. There were few consistent correlations between forage preferences and nutri-tional levels of those forages. However, in one late summer trial, gophers did seem to prefer forage species high in crude protein and apparent digestible protein. This suggests the importance of protein levels in foods of gophers as has been found with other wildlife species and situations.
Pocket gophers are fossorial rodents that cause substantial damage to crops, reforestation, and property. We tested potential repellents to identify candidates to reduce irrigation tubing damage. We dipped carrot chunks in the test materials, using mineral oil as the solvent. Gophers prefer tuberous roots and, when kept in captivity, are often fed carrots as part of their maintenance diet. None of the materials tested proved effective as repellents, even at concentrations as high as 20% active ingredient or in combinations. Wood blocks soaked in a few of the repellents received nearly significantly less damage than the control blocks and could be looked at further as repellents. However, it appears that the quest for an effective gopher repellent will continue to elude researchers.
In terms of internet access, California farmers are some of the most well-connected in the country. According to the USDA, 70% of farms in the U.S. have access to the web as of 2015. In California, 93% of counties exceed that national average. This prompts us to take advantage of the opportunity to employ passive extension approaches, such as websites, which can save both time and resources for Extension audiences and personnel alike. Because digital media can be distributed without the expenses associated with static print resources, this allows us to update our information platforms with greater ease and frequency. Our goal is not to replace print publications, but to adapt Extension resources for a web context and thus connect with a large and geographically extensive audience, especially those who may not customarily seek or have access to more traditional Extension services. A website allows homeowners, landowners, and pest-control professionals to consult this resource freely, at their leisure, and to adopt best management practices more quickly. However, the movement toward cloud-based resources comes with greater web familiarity and thus greater expectations for the websites people use. We are currently developing a ground squirrel best management practices website. In order to provide a user-oriented experience comparable to that of other digital media resources, we need to consider the specific needs and behaviors of a web-based audience. We aim to achieve this by synthesizing new and existing resources into consumable, approachable content on a website that focuses on usability, clarity, visual impact, and site-wide cohesion. We will discuss these goals and how we achieved them.
Barn owls produce large numbers of young, will nest in close proximity, are easily attracted to nest boxes, and occasionally form dense colonies. Their diet consists largely of various species of rodent pests. These characteristics suggest barn owls could contribute to pest control in agriculture. Studies have been conducted in Israel and Malaysia, but little quantitative research has documented their effectiveness. This study measured the effect of a population of barn owls on a rodent population in a 40-ha vineyard near Sacramento, California. In 2011, 11 of 20 boxes were occupied by breeding pairs, fledging 40 young. In 2012, 18 of 24 owl boxes were occupied, fledging 66 young; and in 2013, three of 24 boxes were occupied, fledging nine young. Nocturnal observations revealed the owls hunted the study area heavily. Monthly pocket gopher surveys using the mound-count method indicated that gophers declined on the vineyard with barn owl boxes relative to a control vineyard without barn owl boxes. Pellet analysis showed diet was composed mainly of Botta’s pocket gophers (70.4%) and California voles (26.2%). An infrared camera recorded 316 deliveries to a nest with three chicks (105.3 per chick) over the first eight weeks. Using these figures, and adding conservative estimates of adult consumption over the 165-day breeding season, and adult and fledgling consumption prior to dispersal, the total number of prey taken over the three breeding seasons was estimated to be 30,020 rodents. Cost comparison analysis showed an average cost of $8.11 per pocket gopher trapped versus $ 0.34 per rodent taken by barn owls.
While many raptor species consume rodent pests, the behaviors and habits of barn owls make them particularly suitable candidates for consideration as a viable pest control strategy. As a cavity-nesting species, barn owls will readily nest in man-made structures including nest boxes. Barn owls are also less territorial than many other raptor species and will tolerate other pairs nesting nearby if prey is abundant. Barn owls preferentially consume rodents including voles (Microtus spp.) and pocket gophers (Thomomys spp.) in habitats where they occur, but will also switch to more abundant prey so they may be able to sustain populations even if preferred prey numbers fall. These life-history traits allow for people to inflate barn owl populations in target areas, and this has been a factor in the widespread popularity of encouraging barn owls to nest in agricultural areas to provide natural pest control of small nocturnal vertebrate pests. However, the ability of barn owls to control rodent pests has only been formally tested in Malaysian rice and palm oil agriculture, and whether barn owls are capable of controlling rodent pests to economically acceptable levels in areas such as California is as yet unknown. We extracted and combined data from field studies of barn owl nesting behavior and diet in California vineyards to predict that annually, a pair of nesting barn owls and their progeny will consume 97.85 kg of prey. We predicted that an average barn owl nest in a California vineyard will therefore consume 843 pocket gophers, 578 voles, and 1,540 other prey items, most of which are mice. At these values, a barn owl population density of one nest/10 ha may be able to offset the annual productivity of an average population of pocket gophers, but even the highest barn owl densities of one nest/2 ha would be unable to control pocket gopher populations at maximum densities and reproductive rates. While valuable for making initial predictions of the ability of owls to control small rodent pests, our prediction methods are crude, and accurately assessing the capability of barn owls to control rodent pests will require more field data and more sophisticated modeling techniques.
Field rodents such as common voles cause significant pre-harvest damage during population outbreaks in European agriculture, and commensal rodents such as house mice are of concern worldwide. Usually, rodenticides are applied to minimize damage by these species. Rodenticides are not species-specific and may cause environmental problems. Plant secondary metabolites (PSM) could be used as a tool for sustainable rodent control, potentially minimizing damage and environmental risk. We screened volatile PSMs in feeding trials and in enclosure trials to identify if the odor of herbal substances repelled the target species. In feeding trials, the odor of two PSMs considerably reduced food intake in both rodent species. The use of underground chambers in enclosures indicated three repellent odors were effective for house mice, based on visitation rates of these rodents. Common voles visited the chambers equally independent of treatment and hence showed no avoiding behaviour. Further PSMs, combinations, and varying concentrations will be screened to support development of products. Effective repellents could be used to treat commodities to be protected from rodents and to develop an “odor barrier” against common voles to reduce migration from refuge areas to crops. Our preliminary findings suggest species-specific effects of some PSMs (impact on common voles but not on house mice, and vice versa); this may offer an option to repel unwanted species. Our results contribute to the development of non-lethal management tools for rodent pest species that are potentially more target-specific than traps or rodenticides.
In New Zealand, bovine tuberculosis is a major problem for livestock industries (i.e., dairy, beef, and deer). The disease is managed by TBfree New Zealand (formerly the Animal Health Board) under a National Pest Management Plan with a fixed annual budget of about $53 million. The strategy used to reduce herd infection involves: 1) herd testing and slaughter to remove infection from herds, 2) herd movement controls to minimise the risk of TB being spread between farms, and 3) control of the key wildlife TB vector, the brushtail possum. The management of brushtail possums is the most costly of the three strategy components, and those costs have driven the development of a highly cost-effective possum control contracting industry. Development of an integrated TB management programme involving possum control contractors has required: 1) a defined control target/threshold density for possums that requires numbers be reduced to and maintained at or below for five-seven years for TB to be eliminated, 2) an industry-accepted method for independently assessing whether the control target has been achieved, and 3) training and certification of contractors to independently monitor the possom control contractors. The successful implementation of these three requirements has enabled the industry to develop a performance-based control contract system in which control contractors get paid only if they achieve the required trap-catch target (i.e., contractors take all the risk). PDA/GPS systems with related online databases have been developed to support the management and auditing of contractors, and to capture data about both spatial coverage and control of possums (about 30,000 point data collected per month). The effectiveness of this integrated vector-control programme has enabled more than 1.5 million hectares to be declared TB-free, and reduced infected herds from about 1,700 in the early 1990s to 35 by February 2016.
A Tour de Force by Hawaii's Invasive Mammals: Establishment, Takeover, and Ecosystem Restoration through Eradication
Invasive mammals, large and small, have irreversibly altered Hawaii’s ecosystems in numerous cases through unnatural herbivory, predation, and the transmission of zoonotic diseases, thereby causing the disproportionate extinction of flora and fauna that occur nowhere else on Earth. The control and eradication of invasive mammals is the single most expensive management activity necessary for restoring ecological integrity to many natural areas of Hawai‘i and other Pacific Islands, and has already advanced the restoration of native biota. Science applications supporting management efforts have been shaped by longstanding collaborative federal research programs over the past four decades. Consequently, feral goats have been removed from >1,358 km2, and feral pigs have been removed from >723 km2 of lands in Hawai‘i, bringing about the gradual recovery of forest ecosystems. The exclusion of other non-native ungulates and invasive mammals is now being undertaken with more sophisticated control techniques and fences. New fence designs are now capable of excluding feral cats from large areas to protect endangered native waterfowl and nesting seabirds. Rodenticides that have been tested and registered for hand and aerial broadcast in Hawai‘i have been used to eradicate rats from small offshore islands to protect nesting seabirds and are now being applied to montane environment of larger islands to protect forest birds. Forward-looking infrared radar is also being applied to locate cryptic wild ungulates that were more recently introduced to some islands. All invasive mammals have been eradicated from some smaller islands, resulting in the restoration of some ecosystem processes such as natural forest regeneration, but changes in other processes such as fire regimes and nutrient cycling remain more difficult to reverse at larger landscape scales. It may soon be possible to manage areas on larger islands to be free of invasive mammals at least during seasonally important periods for native species, but at the same time, new mammal introductions continue to occur.
A unique wireless communications and sensor network has been developed by Encounter Solutions Ltd, New Zealand, with a specific aim of fundamentally changing the way pest control operations can be carried out. This wireless technology has the potential to open up new, safer, and more efficient and cost-effective ways of monitoring and servicing control devices. The network is designed for deployment over large areas and can operate where there is no cell phone coverage by making efficient use of satellite technology. It requires very little power to run, and complex high-power radio equipment is not needed. This makes it readily portable, with each sensor node able to operate on small inexpensive batteries for several years. With the help of Hawke’s Bay Regional Council and Auckland Council, the system is presently undergoing trials at a number of New Zealand sites with promising results. Landcare Research New Zealand Ltd has been engaged to evaluate the performance, the effect on contractor behaviour, and to undertake economic analyses of the potential benefits of large-scale roll out of such wireless technology. The first large-scale installation of wireless technology is planned for the 26,000-hectare multi-agency Cape-to-City project. This multi-species predator control project is considered a world-leading programme that will focus on ultra-low-cost, large-scale predator control across productive landscapes. The project aims to restore native biodiversity, whilst at the same time delivering economic benefits to farmers through reduced risk to livestock diseases. If successful, it is anticipated that the Cape-to-City model will be expanded across hundreds of thousands of hectares of the Hawke’s Bay region of New Zealand, with the wireless network being integral to this expansion.
European rabbits threaten ecological, agricultural, forestry, and production assets in Australia, New Zealand, and many oceanic islands where they have become established as invasive pests. Managing rabbits in conservation lands often requires managers to prioritise allocation of funding, while managing them in production lands often requires farmers to know what the benefits and costs are of undertaking control. We aimed to design two Decision Support Systems (DSS) to aid various rabbit management decisions in both conservation and agricultural settings. We describe how our approach: 1) engaged stakeholders to gain their thoughts on the type of decisions that needed support, the issues that they thought were important regarding rabbit management, and the scale and shape of the decision tool they wanted; and 2) produced DSS that were user-friendly, open-sourced, and, most importantly, able to evolve beyond our involvement, which ensures that they stay relevant and current, and are able to improve as new knowledge becomes available. Our approach also placed the DSS within the wider context of rabbit management which highlighted other steps necessary to achieve the ultimate objective of the DSS tool: effective rabbit management to protect and enhance conservation, social, and economic assets. This approach should increase acceptance of the DSS and their limitations but, more importantly, should increase the probability of achieving effective rabbit management.
The California Healthy Schools Act is a right-to-know law that provides parents and staff with information about pesticide use taking place at public schools and child care centers. The Department of Pesticide Regulation (DPR) is committed to encouraging the adoption of integrated pest management to protect children from the potential risks associated with pesticide use in schools. DPR currently offers a suite of training opportunities. New pesticide use reporting and training mandates have allowed DPR to explore new IPM training models that will help increase the adoption of IPM in California schools and childcare centers.
American bullfrogs were introduced to Hawaii’s wetlands from California in the late 1800s. As in other areas where American bullfrogs have been introduced, these voracious predators threaten Hawaii’s native fauna. Of particular concern are Hawaii’s federally endangered endemic waterbirds: the Hawaiian stilt, Hawaiian coot, Hawaiian gallinule, and Hawaiian duck. Wetland managers in Hawaii control bullfrogs for the benefit of these endangered waterbirds. The U.S. Fish and Wildlife Service manages several core wetlands on national wildlife refuges in Hawaii that are necessary for survival of the waterbirds. These refuges include bullfrog control as a management strategy. Unpublished studies on James Campbell National Wildlife Refuge have documented bullfrogs as a major predator of newly hatched endangered waterbird chicks. This refuge currently maintains a year-round bullfrog trapping program with increased effort in the spring during the peak of waterbird breeding. Existing trapping methods employ a simple fish-style funnel trap with red flagging used as an attractant. As part of an effort to improve efficacy of current bullfrog capture methods, we investigated the effectiveness of different attractants for the traps. In addition to the current attractant of red flagging, we tested light, bullfrog call acoustic recordings, and life-size bullfrog decoys. The results showed that most of the treatments were no more effective than the control (no attractant). If we can improve bullfrog trap yields, we expect greater chick survival for the endangered Hawaiian waterbirds.
Influence of Visual Input on Behavior of White-tailed Deer (Odocoileus virginianus) to an Auditory Alert Recording
The objective of this study was to determine the importance of visual verification in the behavioral response of white-tailed deer to an auditory alert recording. We utilized a portable, remote-controlled sound system to play recordings of the white-tailed deer alert “blow.” In Phase I, the sound treatment was administered from a single location in a 1.3-ha grass lawn surrounded by wooded areas and roads with limited visibility, to free-ranging white-tailed deer on the Berry College campus during day and night hours. In Phase II, sound treatments were administered from varying locations in open lawn and hay fields. Recordings of deer activity were obtained from a digital camcorder and a FLIR thermal imagery camera. Behavior of white-tailed deer in response to the audio recording was classified as Passive (no altered behavior), Alert (actively observing and/or listening toward the recorded sound), Active (slow to moderate intentional movement toward or away from the recorded sound), or Flight (running away from the recorded sound). Six 10-sec periods of activity were evaluated. The pretreatment period (Pre Treat) began one minute prior to activation of the alert sound. The next four time periods [Sound (T1-T3)] represent the four consecutive 10-sec time frames from initiation of the sound treatment. A post-treatment (Post Trt) period was approximately 60 sec following the T3 period. In both phases, deer exhibited decreased Passive Behavior and increased Alert Behavior and Active Behavior following administration of the sound treatment. In the more confined area (Phase I) at night, deer tended to exhibit Alert and Active Behaviors longer than during the day. In the more open areas (Phase II), the degree of Active Behavior was diminished, with deer in the day tending to seek out the location of the sound. The results indicate that the use of visual verification to the auditory alert influenced behavioral response of white-tailed deer, and may be more critical in the areas where that process is limited compared to more open landscapes.
Internationally, over the last 20 years the number of tools available for the control of small mammals has declined. Through the efforts of research we have bucked this trend and retained and developed new tools. Three new toxins have been extensively researched and registered, namely para-aminopropiophenone (PAPP) in 2011 for stoats and feral cats; zinc phosphide for possums in 2012; and encapsulated sodium nitrite (ESN) in 2013, for possums and feral pigs. The development of PAPP and ESN, coined red blood cell toxins, developed for humaneness, represent the first new vertebrate pesticides registered for field control of mammalian pests anywhere in the world for >30 years. Research on rodenticides including diphacinone with the additive cholecalciferol (D+C) and a palatable form of norbormide continues. A New Zealand EPA application for D+C was filed in June 2015. More effective killing systems are being researched, and the first successful field trials of resetting toxin delivery devices for possum and stoat control were completed in 2013 and 2014. Improved deployment strategies, integration of humane and selective toxins, lures of greater potency, and improved killing devices aided by species’ recognition will transform ground control for endangered species protection. Sodium fluoroacetate (1080) and other important tools have been retained as new tools are emerging from a research and development pipeline. It is important for the future of New Zealand’s biodiversity that this focused research continues and we continue to learn and advance new technologies. Our goals are shifting to enable reduction in density of rat, stoat, and possum populations to zero over large scales (i.e., elimination at landscape scale), and to hold these at zero through detection and response, including the use of new technologies for perimeter control as part of barrier systems for conservation.
Prolonged persistence of second-generation anticoagulant rodenticides (SGARs) in animal tissues facilitates trophic transfer of residues, with exposure of predatory and scavenging non-target wildlife now widely reported. In many instances, antico-agulant residue levels measured in wildlife are apparently sublethal, although longer-term effects of such exposures are currently not well understood. Conversely, prolonged metabolic persistence is of practical utility when compounds are used as biological markers to determine food uptake by animals. We required two effective and distinct marker compounds to progress field-based research on optimal baiting strategies to manage introduced brushtail possums in New Zealand. Two SGARs (flocoumafen and bromadiolone) were evaluated, as neither are currently registered for application as rodenticides in areas typically subject to possum management. All captive possums ingesting small, sublethal (2-6 g) quantities of food containing 0.0005% (by weight) of either SGAR were reliably marked by the presence of residual concentrations in liver as measured by HPLC analysis. This marking persisted for at least six weeks, and liver concentrations in marked possums did not decline between three and six weeks after the marker was ingested. Marking was also quantitative for both SGARs with a correlation between liver residue concentration and the amount of marker ingested. Using such marker baits would provide at least a six-week period in which to recover possums in field research. By recording bodyweight and testing liver samples from such possums for both markers, regression equations generated from the work reported here will enable back-estimation, with confidence intervals, of the amounts of marker bait eaten by each possum.
In a joint program, Innolytics and the USDA National Wildlife Research Center collaborated in the development of nicarbazin as an avian contraceptive, initially for resident Canada geese and subsequently for feral pigeons. Unfortunately, the introduction of the original goose product, OvoControl G, in 2005, was a commercial failure. Political and social barriers as well as goose reproductive biology effectively thwarted attempts to establish the new technology with any meaningful market success. The introduction of the pigeon contraceptive has been less difficult and the new technology continues to gather momentum. Nevertheless, given the focus on instant results and gratification, contraceptive technology for birds – which works over time – continues to be challenging, and broad market acceptance remains elusive. Especially for short-lived and rapidly reproducing species, however, the market continues to replace outdated or ineffective techniques with the safer and more effective contraceptive tools.
Burrowing rodents, such as pocket gophers (Geomyidae) and voles (Microtus spp.), often cause extensive damage in agricultural, urban/residential, and natural resource areas. Effective management of burrowing rodents typically follows an integrated pest management (IPM) approach that involves a number of tools including rodenticide baiting. However, some of the more commonly used rodenticides have limitations including the development of resistance (e.g., first-generation anticoagulants and strychnine), secondary-toxicity concerns (e.g., anticoagulants), and limited availability (e.g., strychnine). Initial research with combination cholecalciferol plus anticoagulant rodenticides has indicated potential promise at overcoming some of these limitations. As such, we tested the efficacy of several different cholecalciferol plus anticoagulant combinations to determine if they were efficacious in managing Botta’s pocket gophers and California voles in both cage and field trials. Two-choice cage trials for California voles indicated that both pelletized (0.03% cholecalciferol plus 0.005% diphacinone, efficacy = 80%) and bract baits (0.012% cholecalciferol plus 0.002% diphacinone, efficacy = 70%) containing cholecalciferol plus diphacinone (C+D) were efficacious. Further field testing indicated that C+D-coated bract baits (0.014% cholecalciferol plus 0.003% diphacinone) were highly efficacious for vole control (efficacy = 85%), while pelletized baits were less promising (efficacy = 60%). Cage trials indicated that both C+D (0.03% cholecalciferol plus 0.005% diphacinone, efficacy = 80%) and two concentrations of cholecalciferol plus brodifacoum (C+B1 = 0.015% cholecalciferol plus 0.0025% brodifacoum, efficacy = 100%; C+B2 = 0.03% cholecalciferol plus 0.0025% brodifacoum, efficacy = 100%) pelleted baits showed promise as pocket gopher rodenticides. Further field testing of C+D and C+B2 resulted in efficacy significantly >70% (efficacy = 83% and 75%, respectively), although strychnine (0.5%) applications were the most efficacious (efficacy = 100%). Collectively, these results suggest that cholecalciferol plus anticoagulant rodenticides are effective options for managing burrowing rodent populations; they deserve further consideration for registration against these potentially damaging species.
The use of fumigants has been commonly practiced for decades to manage burrowing rodent populations in both agricultural and urban habitats. Stories abound about farmers and ranchers illegally fumigating rodent burrows by inserting toxic gas-producing road flares into burrow openings or by simply piping automotive exhaust into burrows systems. Legal fumigant technology includes incendiary devices such as gas cartridges that produce carbon monoxide, and highly reactive magnesium and aluminum phosphide pellets that produce toxic gasses by reaction with the atmosphere. These devices rely on passive diffusion of the toxic gasses through the burrow system. Recently, products have been introduced to the market that force toxic gasses into burrow systems by using blowers or pressurized gas systems. The effectiveness of fumigation systems where toxic gasses, such as carbon monoxide, are allowed to passively infiltrate burrow systems are limited in their geographical range, and as a result are limited in the potential risk to humans or other organisms. Regardless, these products have traditionally had use restrictions based on the proximity to structures and other inhabited areas. The use of systems where toxic gasses are forcefully blown into burrow systems present a greater hazard potential. This manuscript examines the potential risk, in terms of US EPA Standards, for carbon monoxide exposure; published data on carbon monoxide levels in burrow systems; burrow morphology of various burrowing species; and suggests safe distance standards for burrow fumigation activities conducted around structures and other human-occupied habitats.
Bromethalin is being used more widely for commensal rodent control because of increased regulation on second-generation anticoagulant rodenticides. Wildlife losses in California are tracked by the California Department of Fish and Wildlife. Bromethalin is a neurotoxicant which is not thought to cause secondary poisoning. From August 2014 to January 2016, 24 cases of bromethalin intoxication were investigated in California. These include 11 raccoons, 11 striped skunks, one gray fox, and one fox squirrel. Most of these occurred in Marin County, where active surveillance of wildlife for rodenticide exposure is occurring. Bromethalin exposure should be evaluated when a wild animal that may have accessed bait is showing neurological signs. Trauma and distemper should be ruled out. Histological changes may be found in the central nervous system but are not always present. The tissue of choice for toxicological analysis is adipose. It is likely that bromethalin intoxication is under-reported in the rest of the state and may be mistaken for distemper infection or trauma. Primary exposure of wildlife to bromethalin could be prevented by placing baits in tamper-resistant bait stations.
A Decision Support Tool for Determining Federal Regulatory Authority over Products for Vertebrate Animals
Products developed for vertebrate animals, including toxicants, repellents, contraceptives, vaccines, drugs, antimicrobials, diagnostic kits, and some devices, are regulated under a suite of federal laws. Authorization for the production, sale, and use of these products is primarily controlled by three federal agencies: the U.S. Environmental Protection Agency’s (EPA) Office of Pesticide Programs, the U.S. Food and Drug Administration’s (FDA) Center for Veterinary Medicine, and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS). Furthermore, regulatory oversight of these products extends to research activities conducted during their development. However, determining the regulatory jurisdiction of new products can be confusing for researchers and product developers. In fact, the same product could be regulated under different laws and by more than one agency depending on its intended target population, function, product claims, and route of administration. Adding to this complexity, EPA, FDA, and APHIS have reached a series of formal and informal agreements on which agency will have primary oversight for a number of novel product types that do not clearly fall into established product categories. Here, we present a decision support tool that helps researchers and product developers identify the regulatory jurisdiction of new products, allowing them to comply with federal laws and consult with the appropriate agency early in the research and development phase. Such consultations ensure that resources are spent on studies that satisfy agency-specific data requirements for product registration, approval, and licensing.
The Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), enacted in 1947 and amended in 1972, 1978, and 1988, established federal regulation of pesticides in order to protect human and environmental health. FIFRA has been under the jurisdiction of the U.S. Environmental Protection Agency (EPA) since the EPA’s inception in 1970. Although FIFRA requires EPA to consider the benefits of a pesticide’s use, EPA must ensure that the pesticide is used without posing unreasonable adverse effects to human health or the environment. Furthermore, the Endangered Species Act (ESA), enacted in 1973, requires federal agencies to protect species vulnerable to extinction without consideration of costs. The amendments to FIFRA in 1972, 1978, 1988, and 1996 mandated the EPA review and reevaluate the eligibility of older pesticide products for reregistration under the updated FIFRA standard, while also complying with the new environmental laws of the 1970s. Today EPA’s goal is to review existing pesticide product registrations at least every 15 years under “Registration Review.” To meet their responsibilities under the ESA, EPA is initiating consultations with the U.S. Fish and Wildlife Service (USFWS) during the Registration Review process. The first pesticide active ingredients to advance to consultations under Registration Review are those in gas cartridge products. The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) holds two gas cartridge product registrations. As a federal agency, APHIS also must comply with the ESA and consults with the USFWS on wildlife damage management activities, including tools such as pesticide products. This discussion presents APHIS’ unique ground view as a federal agency navigating the EPA’s ESA consultations during the Registration Review process, and describes the mitigation measures and their impacts on APHIS Wildlife Services’ activities.