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The concepts of “integrated control” and “integrated pest management” (IPM) were devised by entomologists, but they proved relevant to the monitoring and control of virtually any agricultural pest (i.e., weeds, fungi, vertebrates). Within IPM, economic threshold characterized pest densities that would have negative impacts and economic injury level characterized amounts of predicted crop injury (destruction) that would allow recovery of potential pest-control costs. Approximately 150 species or groups of vertebrates have been documented to pose human health/safety risks or to cause agricultural, natural resource, and property losses in North America. Rodent (e.g., mice, rats, ground squirrels) and bird (e.g., blackbirds, gulls, cormorants) populations are the most frequently cited species/groups of vertebrates linked with IPM. Uncertainty characterizes IPM applications to control damage by these species/groups. Uncertainty is a measure of variance, which occurs due to the myriad of biological, crop, economic, meteorological, pesticide, production, seasonal, and soil unknowns that impact IPM programs. Six uncertainty-reduction techniques are commonly used by economists: 1) worst-/best-case scenario, 2) contrived scenarios, 3) decision tree analysis, 4) sensitivity analysis, 5) Monte Carlo simulation, and 6) systematic projections. This paper reviews key IPM literature, especially economic literature, and discusses techniques that can reduce the economic uncertainty of using IPM programs with vertebrates.

California is the nation’s greatest agricultural producer. In 2006, California’s gross value of agriculture production was more than $38.3 billion, almost double the value of production for the second most important agriculture state, Texas. The agricultural sector is a fundamental segment of any economy because it not only contributes substantially to the general economy and employment of the region, but it is additionally linked to almost all other sectors in the economy (i.e., manufacturing, retail trade, and accommodation and food service) as a source of inputs. Damage to crops by birds and rodents can reduce total crop yield and increase pest control costs. This ultimately reduces the production output of the agricultural sector and all other linked sectors and could potentially have significant total economic impacts. One method to estimate the total impact to the California economy of a decrease in agricultural yields and increase in pest control costs as a result of bird and rodent damage is an input-output (IO) model. To capture the sub-regional effects of economic changes, IO modeling is done at the county level. For the initial phases of this project, a deductive process was used to systematically rank California counties according to gross value agricultural production, value of production of targeted crops, and concentration of targeted crops. This process was used to identify the 10 leading agricultural counties, out of California’s 58, that will be processed for IO modeling to measure economic impact of bird and rodent damage on employment and revenue in each of these counties.

This paper presents a general summary of an economic assessment of the United States Department of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), Wildlife Services (WS) Program in California (CA). Detailed analyses quantified WS economic benefits to each of the 38 counties that contributed cooperative funds in 2004, with an aggregate report of county results used to form an overall statewide estimate of the Program’s value. Four general categories of wildlife damage management activities were: Agriculture, Health and Human Safety, Natural Resources, and Property. Two general methods of determining economic valuation were employed to quantify benefits: replacement-cost method, and damage-avoided method. Results showed that the protection of livestock, particularly sheep, cattle, and goats, from predation was a main activity of WS–CA personnel in each of the cooperating counties. Annual estimated replacement costs for WS–CA operations for Year 1 and Year 2 of the analysis (i.e., approximately equivalent to fiscal years 2003 and 2004, respectively) totaled $6,605,234 and $8,602,590 for the combined counties, respectively. Mean replacement costs for WS operations in the cooperating counties in Year 1 and Year 2 equaled $173,821.95 and $226,373.13, respectively. Given that the counties paid an average $51,798.10 share to WS–CA in 2003, the counties would have incurred averaged net increased expenses of $122,023.85 and $174,575.03 for similar services offered by commercial wildlife damage management companies.

This paper describes issues and concepts relevant to economic modeling of oral rabies vaccination (ORV) campaigns for managing wildlife rabies. Economic models of ORV are mathematical expressions used to predict and draw inferences about the costs and savings likely to be recouped by these rabies management efforts. Costs that are prevented due to ORV campaigns convert to savings. Comparison of campaign duration, bait cost, bait density, and bait distribution data for North American ORV campaigns showed that: 1) campaigns are lengthy, 2) those involving raccoons entail greater bait densities (i.e., related bait costs) and per unit area bait-distribution costs than those involving foxes and coyotes, and 3) all entail “enhanced” surveillance and establishment of maintenance barriers (i.e., deter translocation or reintroduction of new cases) upon completion. Key modeling issues were: model parameterization, ORV cost variables (i.e., bait costs, bait densities, and unit area distribution costs), time horizon, contingency costs, and ORV host specificity.

A comprehensive cost model of wildlife rabies is presented. A total of 11 factors were viewed to comprise the diverse agricultural, insurance, medical, and veterinary expenses associated with rabies (i.e., pet vaccinations, livestock vaccinations, pet replacements, livestock replacements, pre-exposure prophylaxis for humans, post-exposure prophylaxis for humans, adverse medical reactions, animal control activities, public health charges, quarantine costs, and human death settlements). These factor costs form the basis of potential savings to be gained from rabies control activities. Irrespective of incidence, per unit costs and ranges were found to be greatest for livestock replacement, post-exposure prophylaxis, adverse medical reactions, and human death settlements, with substantial costs of adverse medical reactions and human deaths occurring infrequently but due to potential insurance or litigation claims. Empirical studies are needed to document the incidence of these factors during pre-epizootic, epizootic, and post-epizootic phases of wildlife rabies.

Iterative (1 variable-changed-at-a-time) Lotus 1-2-3® spreadsheet calculations were used to derive hypothetical benefit:cost ratios (BCRs) based on the recommended-use patterns for a commercial turf repellent (Rejex-It®) to deter Canada geese from grazing/loafing on golf fairways and for a commercial shrub/plant repellent (Deer I Repellent®) to deter deer from browsing on landscape shrubbery. Scenarios were based on “real-world” costs of products and valuations of resources. Plots of the BCR-response surfaces for Rejex-It® on fairways showed that BCRs for these turf applications ranged between 63.9 and 0.73. These BCRs showed transitivity, with highest to lowest BCRs linked with revenues from 90+ foursomes per day, 28-day spray intervals, 3.34 ha of fairways, and a $2.00/ha application cost versus 45+ foursomes/day, 7-day spray intervals, 10.24 ha of fairways, and a $10.00/ha application cost, respectively. A plot of BCRs for using Deer I Repellent® based on replacement outlays for shrubs yielded BCRs between 47.12 and 0.52. This response surface yielded transitivity within shrub-size/-number classes and had enhanced “scallop;” all BCRs for 6 and 12 spray applications involving 10-40 shrubs, 0.305-1.122-m radius plants, and 20-100% damage were ≥2.27 (i.e., more than double the cost outlays for the chemical). Although requiring a number of assumptions, our approach provides useful decision-making aids for persons interested in the economics of wildlife damage management methods. The main advantage is that projections of the combinations of variables associated with the potential “break-even” point (BCRs =1.0) for these interventions are available a priori, and that scenarios can be modified with relative ease to view the benefit-cost impacts of other input variables or model assumptions.

Benefit-cost analysis (BCA) involves comparing all of the gains and losses from a given wildlife damage management action or management technique over time in similar units, thereby providing a total picture of potential gains and losses to society. This technique is at the core of justifications for wildlife damage management efforts. BCA has been noticeably absent from the study of vertebrate pest management problems, and in the few studies where a BCA has been included, the analysis is incomplete. This paper provides an overview of the steps in a BCA, using specific wildlife damage examples to highlight and expand the technique for researchers interested in documenting these effects.

As part of efforts to develop The Livestock Protection Collar (U .S. EPA Reg. No. 56228-22), we videotaped sheep-predation events by 23 (15 male and 8 female) wild-caught, confined coyotes (Canis latrans) in a 31 × 41-m enclosure. Coyotes were paired individually with a sheep (Ovis aries) during 1-h daily trials. Nineteen (13male and 6 female) of the coyotes made 75 fatal attacks of 1 to 7 sheep each; 4 coyotes (2 male and 2 female) made no fatal attacks despite 19 to 39 daily pairings. Of coyotes that made fatal attacks, 13 (9 male and 4 female) always attacked at the neck of sheep; 5 (4 male and 1 female) always attacked by nipping at the legs/head/back of sheep; and 1 attacked at the legs/head/back of sheep during two initial events, but subsequently attacked at the neck of sheep. Greater time in captivity was not correlated with trials preceding a fatal attack (rho= +0.23). Among coyotes making ≥2 fatal attacks, subsequent predation events occurred after fewer intervening pairings with sheep. Initial feeding sites occurred most frequently at the flanks/ribs of sheep. Although collected between 1976 to 1980, these observations represent a never-to-be-acquired-again data set that remains timely. Data showed that not all coyotes display sheep-predation behaviors or kill sheep efficiently. Instrumental learning and stimulus-habituation models of coyote predation behavior are discussed.

Factors affecting soil-contact and -manipulation behaviors of pocket gophers (Thomomys and Geomys spp.) are poorly understood. Delineation of these behaviors is crucial to development of new repellent systems that seek to exploit the fossorial activity of these rodents. In a laboratory study involving northern pocket gophers (Thomomys talpoides), I examined the effects(s) of gravimetric soil moisture (i.e., 0%, 5%, 10%, 15%, 20%, and 25%) upon soil-contact and -use behaviors. Six gophers received successive, 0.5 h/day exposures to one of the moist soils compared to dry (0%) soil in a 2-choice apparatus. Times in each compartment and observed behaviors were recorded. A chamber × moisture interaction was attributed to the avoidance of 25% moist soil. A qualitative description of 37 locomotor, postural, sniffing, grooming, feeding, and soil-manipulation responses is provided.

This paper describes several unexpected benefits of rodenticide-registration research funded by the California Bait Surcharge Program. An enclosure-type study was conducted to determine efficacy of single, pre- and test-bait broadcasts (10 lb./ac.) of 0% and 2% zinc phosphide (Zn3P2, CAS #1314-84-7) steam-rolled-oat (SRO) groats to control voles (Microtus spp.) in alfalfa (Medicago sativa). Unexpected research spinoffs resulted from the use of: 1) eight randomly-located, sieved-dirt plots per enclosure to monitor bait distribution, bait removal, and rodent/avian (non-target) activity; 2) a bait-weathering plot and bait-sample analyses to monitor Zn3P2 biodeterioration; and 3) a C++- language program to derive theoretical benefit-cost ratios associated with Zn3P2-bait broadcasts

Zinc phosphide (Zn3P2, CAS #1314-84-7) is an acute rodenticide having numerous agricultural applications. This paper estimates the risk of mortality posed to domestic cats (Felis domesticus) and dogs (Canis familiaris) from ingestion of voles (Microtus spp.) that succumb to 2.0% Zn3P2 baits. Following a brief review of direct/indirect studies and incident reports relevant to nontarget-Zn3P2 effects and vole control, four scenarios of vole-carcass ingestions needed for light and heavy cat and dog predators/scavengers to receive approximate lethal doses (ALDs = 40 mg/kg) of undigested rodenticide are described. Scenarios were derived using values reported by Sterner and Mauldin (1995) as the maximum 8.2 mg Zn3P2 ingested (ad libitum) and average 1.7 mg Zn3P2 whole-carcass residue. Extrapolating these "worst-case" loads to 2 and 6 kg cats and 1 and 36 kg dogs showed that between 5 and 847 Zn3P2-baited vole carcasses must be consumed in fairly rapid succession for these nontargets to ingest cumulative ALDs. The likelihood that even light (≤ 1-2 kg) cats and dogs will find and rapidly (≤ 24 h) ingest multiple (≥ 5) Zn3P2-dosed vole carcasses under registered applications seems remote.

Public and governmental concerns about the health, safety, and environmental impacts of pesticides have led to increased regulatory requirements to determine the hazards and risks associated with their manufacture, distribution, and use. Vertebrate pesticides are regulated by the U.S. Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), as amended. Much of the data required for registration of these pesticides will be generated by commercial testing laboratories under contract to the product registrants or sponsors. In this paper, we address aspects of the contract research process including: 1) an overview of FIFRA requirements, 2) the nature of the contract research process, 3) guidelines for setting up and administering a contract for this type of work, and 4) several case studies to illustrate some of the "pitfalls" that may be encountered. The information presented is based on the collective experience of the authors' involvement with 49 contracted studies over a three-year period.

The U.S. Department of Agriculture (USDA), Animal Plant and Health Inspection Service (APHIS) maintains six federal registrations for zinc phosphide (Zn3P2); three of these address the control of eight rodent species using steam-rolled oats (SRO) or wheat grains in diverse applications. Optimal foraging theory (OFT) and "particle dose analysis" (PDA) afford predictions relevant to the efficacy, acceptance, bait shyness, and non-target hazards of these Zn3P2 baits. For PDA, numbers of SRO groats or whole wheat grains associated with acute oral median lethal (LD50) or approximate lethal (ALD) doses of Zn3P2 were compared among nine target rodent and eleven non-target avian species. Key outcomes were: 1) mean (±S.D.) SRO groats and wheat grains weighed 23 (±9) and 18 (±9) mg [assumed to carry ≈0.46 (2.0%) and ≈0.33 (1.82 %) mg Zn3P2, respectively; 2) published acute oral LD50 values for the target rodents ranged between 16.2 and 18.0 mg/kg, with a 42.0 mg/kg ALD cited for the white-footed mouse (Peromyscus maniculatus); 3) estimated minimum-maximum number of SRO groats and wheat grains needed for ingestion of the LD50/ALD doses by target species were 1.6 to 39.1 and 1.7 to 3.8, respectively; and 4) estimated minimum-maximum number of SRO groats and wheat grains associated with primary LD50/ALD hazards to nontarget avian species were 1.3 to 175.8 and 1.8 to 245.1, respectively. Theoretical implications of OFT and PDA to efficacy, acceptance, bait shyness, and specificity of Zn3P2 baits in rodent control are provided; the potential effects of food-handling time, bait-search time, predator density, social-dominance hierarchy, food-intake pattern, and bait-distribution pattern are discussed.

The 1988 Amendments to the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) accelerated the reregistration schedule for pesticide products registered with the Environmental Protection Agency (EPA) prior to 1984. The compound 3-chloro-p-toluidine hydrochloride (DRC-1339), an avicide registered to control 14 pest bird species, was included on Pesticide List B published by EPA. For the reregistration of DRC-1339, 44 studies were required− 22 product chemistry, 7 wildlife/aquatic hazards, 8 human/domestic animal hazards, 5 environmental fate, and 2 residue chemistry studies. In 5 acute human-health-hazards studies, DRC-1339 was found to: (1) have an oral LD50 of 330 (272-401) mg/kg in rats, (2) have a dermal LD50 of >2.0 g/kg in rabbits, (3) cause corrosive effects to the eyes of rabbits, (4) cause corrosive effects to the skin of rabbits, and (5) induce dermal sensitization in guinea pigs. Results support the current precautionary statements on the "use labels" warning of harmful ingestion, inhalation, dermal absorption and eye irritation effects to users of the active ingredient.

Rabies continues to pose major public health concerns in Canada and the United States (1-5). Effective pet vaccination programs have controlled rabies in domestic dogs (Canis familiaris) in both countries, [...]

The use of LiCl-treated baits and carcasses has been advocated as a means of controlling coyote predation on sheep through a process known as "aversive conditioning or taste aversion." While some investigators have made well publicized claims of damage reduction through the use of LiCl on sheep ranges, other researchers have experienced difficulty establishing prey aversion in captive coyotes. The conflicting results suggest a need for extensive, carefully controlled research in both pen and field situations before valid conclusions can be reached regarding aversive conditioning as a depredations control method.