Human Conflicts with Wildlife: Economic Considerations

THE ECONOMIC IMPACT OF INVASIVE SPECIES TO WILDLIFE SERVICES’ COOPERATORS

David L. Bergman et al. — Thu, 08 Feb 2007 13:07:29 PST

On February 3, 1999, the president of the United States signed an Executive Order 13112 on invasive species. Each federal agency was directed to detect and respond rapidly to control populations of invasive species, monitor invasive species populations, provide for restoration of native species and habitat conditions, conduct research on invasive species and develop technologies to prevent their introduction, and promote public education on invasive species and the means to address them. The United States Department of Agriculture’s Wildlife Services Program fulfills a federal responsibility for helping solve problems which occur when human activity and wildlife, including invasive species, are in conflict with one another. This is accomplished through the recommendation and/or implementation of integrated pest management strategies (IPM). IPM strategies often involve both technical assistance and direct management. This paper provides a summary of 8 years of Wildlife Services involvement in the resolution of invasive species conflicts with agricultural resources, property, human health and safety, and natural resources.

WILDLIFE IMPACTS ON FOREST RESOURCES

Dale L. Nolte et al. — Thu, 08 Feb 2007 13:06:17 PST

The negative impacts of wildlife on forest resources can be extensive. This paper provides some insight into the economic and environmental consequences of wildlife damage to forest resources and a brief overview of the damage inflicted by select wildlife species. Probably the most thorough measure of wildlife damage to forests in the Pacific Northwest was initiated in 1963 and 1964 by the Committee on Animal Damage Survey of the Western Forestry and Conservation Association. This study estimated that 30% of the tree seedlings planted would be damaged if no preventive practices were implemented; stocking rates on unprotected sites were 75% of those on protected sites; and trees protected from animal damage were 33% taller than unprotected trees after 5 years. Updating the economic numbers to reflect present day values, this damage results in an annual financial loss in Oregon of US$333 million. The total predicted reduction in value of the forest asset in Oregon, if no animal damage management was practiced, was estimated to be US$8.3 billion. Results from a recent survey conducted by the Oregon Forest Industry Council also provides insight into economic losses due to damage by select species: mountain beaver (US$6.8 million) and bear (US$11.5 million).

PIECES OF SILVER: EXAMPLES OF THE ECONOMIC IMPACT AND MANAGEMENT OF THE SILVER GULL (LARUS NOVAEHOLLANDIAE) IN MELBOURNE, AUSTRALIA

Ian D. Temby — Thu, 08 Feb 2007 13:04:05 PST

Like a number of gull species, the silver gull Larus novaehollandiae has expanded its population in response to human food subsidy. The major anthropogenic food source is food waste at rubbish tips. Other sources of human food waste are also exploited. Many problems result from the activities of these birds, including human health and safety, economic impacts, and effects on the conservation of other species. My study examines aspects of the economic impacts of the silver gull on the human community of the Greater Melbourne Area comprising approximately 4065 km2 (1569 square miles). My data collection method involves identifying sites where problems have been experienced and completing questionnaires during face to face interviews with the managers of those sites. Data collected at this early stage of the study demonstrate that there are significant, quantifiable economic impacts associated with the superabundance of the silver gull in this area. Other impacts, such as reduced amenity and potential health hazards are equally real but more difficult to quantify. Costs include damage to structures and products, damage prevention measures, and loss of production. Information about the costs of these problems will be presented to the relevant landfill management authorities to encourage them to consider alternative means of disposing of putrescible waste, rather than by open landfill disposal, because even current best practice management of open landfill sites (rubbish tips) provides ample opportunity for silver gulls and certain other bird species to exploit this food source. Controlling access by the silver gull to food at rubbish tips would be an important first step in managing the population of this species.

THE COSTS OF BIRD STRIKES AND BIRD STRIKE PREVENTION

John R. Allan — Thu, 08 Feb 2007 13:00:54 PST

Collisions between birds (and other wildlife) and aircraft are known to cause substantial losses to the aviation industry in terms of damage and delays every year. Techniques exist to control bird numbers on airfields and hence to reduce the number of wildlife strikes, but they are applied at widely different levels from airport to airport. Some of this variation may be due to differing levels of strike-risk at the different sites, but much of it is due to the unwillingness or inability of the airports concerned to invest in bird strike prevention. Part of the reason for this reluctance to invest in airport bird control is a lack of understanding of the true costs to the airlines in terms of direct damage to aircraft and in delays and cancellations. Previous estimates of the cost of bird strikes have concentrated only on measurable repair costs and have not attempted to assign costs to aircraft delays. My paper uses newly available data from major international airlines to provide the first estimate for the total cost of bird strikes to the world’s airline fleet. Much of the data are commercially confidential and sources cannot be quoted nor the accuracy of the data verified. The estimates also rely on information from a very small number of airlines to produce extrapolations for the worldwide costs of damage and delays. Although these are major international carriers, and as representative as possible of the world bird strike problem as a whole, the results should be interpreted with a suitable level of caution. A tentative and probably conservative estimate of US$1.2 billion per year in damage and delays is the outcome of this calculation. The costs of bird damage are evaluated relative to the ability of managers to pay for bird control programs and the derived benefits thereof. Reasons for the industry’s failure to invest further to reduce the costs of bird strikes are examined.

CORMORANT DEPREDATION LOSSES AND THEIR PREVENTION AT CATFISH FARMS: ECONOMIC CONSIDERATIONS

James F. Glahn et al. — Thu, 08 Feb 2007 12:56:00 PST

Although several piscivorous birds are involved in depredation conflicts with southern aquaculture, the double-crested cormorant causes some of the most widespread and significant problems to catfish, the dominant industry. Unlike other agriculture commodities, catfish losses due to predation cannot be directly measured, so we review several approaches taken to estimate these losses. Although these approaches are valid for predicting the costs of simply replacing these fish at the time of predation, they have been criticized because they failed to consider the functional relationships between predation and output parameters at harvest. Recent controlled experiments are reviewed that confirm previous estimates of predation losses and start to examine output parameters at harvest with and without cormorant predation. In the latter case, enterprise budgets suggested that the 20% production loss observed at harvest from simulating 30 cormorants feeding at a 6-ha catfish pond for 100 days (500 cormorant-days/ha) resulted in a 111% loss of profits. These results confirm previous estimates suggesting that efforts to repel these birds from ponds are well justified and are economically reasonable. We review cost estimates of the most widely used method at catfish farms, “the harassment patrol” and the limitations of this procedure. In addition to the harassment patrol, most Mississippi catfish farmers in recent years have participated in a cormorant roost dispersal program each winter. We review the costs of these programs and the benefits incurred. Although very little attention has been paid to the effect of changes in culturing practices on mitigating predation losses, increasing fish stocking rates is a current trend in the industry. We examine data from research ponds stocked at these high fish densities and relate various levels of observed fish mortality to production at harvest. Assuming that the observed fish mortality was caused by cormorant predation, regression models suggest a higher threshold for cormorant predation impact at these stocking rates.

HAS AN INTEGRATED PEST MANAGEMENT APPROACH REDUCED BLACKBIRD DAMAGE TO SUNFLOWER?

George M. Linz et al. — Thu, 08 Feb 2007 12:53:49 PST

Since the mid-1970s many new and modified damage abatement methods have been implemented to reduce blackbird damage to ripening sunflower in the northern Great Plains. Concurrently, estimates were made of breeding blackbird densities and sunflower damage to track changes in population size and chart progress toward reducing damage. Breeding density estimates were made at both the regional and county levels, whereas sunflower damage estimates were made at the county level only. Periodic regional estimates of breeding densities, between 1967 and 1998, showed that numbers of red-winged blackbirds (Agelaius phoeniceus) and yellow-headed blackbirds (Xanthocephalus xanthocephalus) did not differ among years, while common grackle (Quiscalus quiscula) numbers tended to increase. To improve our ability to detect changes in breeding density, we started intensive county-level surveys in 1996. These surveys, conducted in 4 counties in North Dakota and South Dakota, showed that blackbird densities differed among years from 1996 to 1999. We surveyed sunflower damage in 2 of these 4 counties from 1994 to 1998 and found no difference in damage (Χ̅ = 1.8%) among years. In 1997 and 1998, with an additional 2 counties added to the survey, we again found that damage was similar between years, averaging 2.2%. Overall, breeding blackbird densities have increased in recent years, but dollar loss per hectare trended lower in three of the study counties that had historical databases for comparison. We will continue to use annual estimates of breeding densities and sunflower damage to assess the effects of an evolving integrated pest management program.

BROWN TREESNAKE CONTROL: ECONOMY OF SCALES

Daniel S. Vice et al. — Thu, 08 Feb 2007 12:49:38 PST

The accidental introduction of the brown treesnake (Boiga irregularis) to Guam led to the demise of most of the island’s native avifauna and herpetofauna. The snake is also responsible for significant economic losses through frequent power outages and consumption of poultry. Control of the snake, aimed at preventing its inadvertent dispersal from the island and protecting native wildlife and economic resources, is accomplished using specially designed snake traps, hand capture, snake detector dogs, and snake barriers. Although control tools capture large numbers of snakes, control efforts are labor intensive, costly, and ineffective in reducing snake populations across the unbroken forested landscapes found throughout much of the island. The efficacy of control methods has been widely researched; however, no comprehensive evaluation of the costeffectiveness or ideal integration of control tools in differing scenarios has been completed. In this paper, we present an overview of current federal control efforts and discuss the costs and limitations of snake control.

EVALUATION OF WILDLIFE DAMAGE TO FORESTS IN GERMANY

Markus J. Schaller — Thu, 08 Feb 2007 12:47:23 PST

Legal regulations concerning wildlife damage in Germany are totally different from regulations in the United States. In certain cases German game laws provide the right to compensation for wildlife damage to forests for forest owners. But not everyone has to be compensated. Liability exists only for damage caused by hooved game, rabbits, and pheasants, and only to important local tree species (Hauptholzarten). If, for example, red deer damage an afforestation of Norway spruce (Picea abies) by browsing, normally the shooting tenant has to compensate for the damage. The most important types of damage to forests in Germany are browsing and debarking by red deer (Cervus elaphus) and browsing and rubbing by roe deer (Capreolus capreolus). For a forest owner to gain compensation, a special procedure is prescribed in the game laws. If no amicable agreement between shooting tenant and forest owner can be reached, a forest expert has to evaluate the economic damage. Therefore, in Germany, several methods of economic assessment of damage to forests caused by wildlife have been developed. Two methods in use are presented and discussed.

ECONOMIC ANALYSIS OF A LARGE SCALE ORAL VACCINATION PROGRAM TO CONTROL RACCOON RABIES

Philip Kemere et al. — Thu, 08 Feb 2007 12:45:01 PST

Since the late 1980s, results of oral vaccination trials in several states have provided growing evidence that this vaccination method may be effective for controlling the spread of rabies in raccoons (Procyon lotor). This study examines the economic feasibility of using oral vaccination on a larger scale than previous trials. We analyze the benefits and costs associated with a hypothetical barrier that would stretch from Lake Erie to the Gulf of Mexico, combining natural geographic features provided by the Appalachian Mountains with oral vaccination zones. The goal of this barrier would be to prevent the raccoon rabies variant from moving west into broader geographic regions of the United States. The costs of establishing and maintaining this hypothetical barrier are compared to the avoided costs of not having to live with raccoon rabies west of its current distribution. The westward advance of raccoon rabies, if it is not contained, is projected using simple models based on constant rates of spread. Our results show that preventing the westward movement of raccoon rabies by combining an oral vaccination program with natural barriers may be economically feasible. Discounted costs of establishing and maintaining the barrier are estimated to total between US$58 million and US$148 million. Net benefits of program implementation range between US$48 million and US$496 million for a variety of models, including ones that exclude forgone pet vaccination expenditures. The analysis also provides a framework for developing future models to explore the benefits and costs of eliminating raccoon rabies from currently affected areas.

ECONOMIC TOOLS FOR MANAGING IMPACTS OF URBAN CANADA GEESE

Nicole H. McCoy — Thu, 08 Feb 2007 12:42:53 PST

Management of urban Canada geese impacts can be assisted by the use of economic analyses of both the problem and the proposed solution. Management of a species that is both geographically mobile and stationary, protected by the Migratory Bird Act of 1918, and loved by much of the public while posing a significant risk of damage to both private and public property is a difficult task. The issue is further complicated by the scope and scale of urban goose impacts. While the presence of urban Canada geese results in both positive and negative impacts, this paper will focus primarily on the management problems involving overabundance and concentrated populations. The many negative impacts caused by Canada geese may occur at a “lawn” level, or be aggregated into a “community” level. Management actions that solely focus on the “lawn” level may shift the problem to other parts of the community. Economic analysis provides a venue for management strategies, either individually or in aggregate, to be evaluated in a common time frame that accounts for their real costs and resulting benefits. Three economic techniques can be used to evaluate management strategies at any geographic level: economic feasibility, economic efficiency, and cost-effectiveness analysis.

THE ECONOMICS OF MANAGING BELDING’S GROUND SQUIRRELS IN ALFALFA IN NORTHEASTERN CALIFORNIA

Desley A. Whisson et al. — Thu, 08 Feb 2007 12:38:40 PST

We used estimates of yield loss from 1995 to 1999 and the reported costs and effectiveness of available control methods to provide a basis for developing a cost-effective management strategy for Belding’s ground squirrels in alfalfa in northern California. Mean annual losses varied between US$110/ha and US$300/ha of alfalfa. Growers usually spend less than US$25/ha on control methods that are implemented haphazardly and provide poor control. We suggest that growers can afford to spend more on control methods such as burrow fumigation or exclusion fencing that previously have been viewed as being too expensive. Control efforts should be focused on new fields supporting low-density populations.

AN ANALYSIS OF DEER-VEHICLE COLLISIONS: THE CASE OF OHIO

Kurt A. Schwabe et al. — Thu, 08 Feb 2007 12:36:32 PST

The costs of deer-vehicle collisions (DVCs) in Ohio are estimated to be in excess of US$52 million annually. The intention of this paper is to identify factors contributing to the abundance of DVCs in Ohio, calculate the average cost of a deer-vehicle collision event, and illustrate the potential gains in economic efficiency from alternative approaches for reducing DVCs. Our results suggest that large potential economic gains from reducing DVCs in Ohio exist and that the optimal strategies for achieving these reductions seem to combine both changes in deer management schemes and deer-vehicle mitigation strategies.

ECONOMICS OF PREDATION MANAGEMENT IN RELATION TO AGRICULTURE, WILDLIFE, AND HUMAN HEALTH AND SAFETY

Michael J. Bodenchuk et al. — Thu, 08 Feb 2007 12:34:24 PST

Predation management is controversial and much recent debate has focused on the cost of management efforts. This manuscript considers the cost of predators to agriculture, big game or threatened and endangered species management, and human health and safety. Subsequently, the cost of efforts to manage predation in these contexts is discussed, and benefit:cost ratios are calculated. When properly applied, predation management shows benefit:cost ratios of between 3:1 to 27:1 for agriculture and 2:1 to 22:1 for wildlife protection. For human health and safety, benefit:cost ratios are more difficult to calculate, but we argue that benefits outweigh costs in many different areas. We conclude that in terms of benefit:cost returns on investment, predation management is an extremely efficient means of protecting livestock, wildlife species of concern, and human health and safety.

USING BIOECONOMIC MODELS TO MAXIMIZE BENEFITS FROM VERTEBRATE PEST CONTROL: LAMB PREDATION BY FERAL PIGS

David Choquenot et al. — Thu, 08 Feb 2007 12:32:16 PST

The question “When should investment in pest control stop?” either explicitly or implicitly underpins decisions concerning pest control made at every level of enterprise or government, regardless of whether these decisions are tactical or strategic. Bioeconomic modeling provides a quantitative framework for considering the benefits and costs of alternative pest control strategies. In this case study, we develop 3 bioeconomic models that examine strategies based on helicopter shooting and 1080 poisoning, for reducing feral pig (Sus scrofa) predation of newborn lambs in wool-growing enterprises located in Australia’s rangelands. In the first model, marginal analysis indicated that helicopter shooting was more profitable than 1080 poisoning when pasture biomass was above 220 kg•ha^-1, and was most profitable when feral pig density was reduced to 1.5•km^-2. Below pasture biomass of 220 kg•ha^-1, 1080 poisoning became more profitable than helicopter shooting. The second model added logistic population growth for pigs so that control could be simulated through time. While the net benefit from helicopter shooting was still maximized when applied annually, and the profitability of 1080 poisoning was still dependent on pasture biomass, the return on investment from both strategies increased markedly. While the third model, which added stochastic environmental variation, further increased the profitability of control, it also introduced uncertainty to the net benefits realized. For helicopter shooting, annual application remained most profitable.

DEVELOPMENT OF A MODEL TO ASSESS RODENT CONTROL IN SWINE FACILITIES

Kurt C. VerCauteren et al. — Thu, 08 Feb 2007 12:30:10 PST

At the request, and with the support, of the National Pork Producers Council we are conducting a comprehensive economic analysis of rodent control in swine production facilities. The authors represent an interdisciplinary working group that has been assembled to identify all necessary input variables and values associated with rodent damage and control. The working group consists of specialists in swine production, facilities management, agricultural economics, swine health, rodent control, the pest management industry, systems modeling, and distance education. We incorporated data from the scientific literature and personal experience into an interactive STELLA systems model. The model generates benefit-cost analyses and predicts outcomes of various levels of rodent control. Our simulations suggested that rodent damage and rodent control costs were minimized when US$350/month was spent on control. Further, simulations showed that net costs of rodent damage and control could be optimized at US$0. Eventually, the decision-assisting model will be made available to swine producers through Extension Agents and the Internet.

IMPACTS OF HOUSE MICE ON CROPS IN AUSTRALIA - COSTS AND DAMAGE

Peter R. Brown et al. — Thu, 08 Feb 2007 12:26:52 PST

Rodents cause serious losses to crops in many different parts of the world. The house mouse (Mus domesticus, Schwarz and Schwarz 1943) is a serious pest to agriculture in Australia. The impacts of house mouse damage to crops in Australia were examined. Plagues of mice (>1,000 mice/ha) cause enormous economic and social stress to rural communities in Australia. The mouse plague in 1993/94 caused about US$60 million in damage to crops, intensive livestock industries, and rural communities. The impact of mouse plagues is generally well understood, but there is a dearth of knowledge about the relationship between mouse densities and the degree of mouse damage to particular crops types. This paper examines the relationships between the abundance estimates of mice and the damage they cause to crops at sowing and prior to harvest. Crop types examined were wheat, flood irrigated rice, irrigated soybean, and maize. Estimates of damage were obtained by counting the number of tillers (or pods) that were damaged by mice. The results from two field seasons show that mouse population abundance was low (< 75 mice/ha) and the damage to crops was low also (generally < 5%). The positive relationship between damage and the abundance was weak for wheat crops prior to harvest, strong for damage to soybean crops, and unclear for rice and maize crops. More data are required over a wider range of mouse densities. The available data on the effectiveness and costs of mouse control were summarized. These data were used to build an economic model to provide better options for the management of mice. The model will be incorporated into a system for information transfer and decision support for the management of mouse plagues (Mouser CD-ROM).

SPREADSHEETS, RESPONSE SURFACES, AND INTERVENTION DECISIONS IN WILDLIFE DAMAGE MANAGEMENT

Ray T. Sterner — Thu, 08 Feb 2007 12:15:00 PST

An a priori approach to examining the economics of performing management activities to reduce agricultural and resource damage by wildlife is described. Computer spreadsheet procedures are used to derive response surfaces of potential net savings and benefit:cost indices for selected crop- or resource-protection activities. Tabular and graphical displays of these indices afford decision-making aids for wildlife-damage interventions. An example based on the use of an acute rodenticide, zinc phosphide (Zn₃P₂), for vole (Microtus spp.) control in alfalfa (Medicago sativa) is described. Iterative calculations were derived for 1,260 possible combinations of 3 field-size, 6 crop-loss, 7 bait-effectiveness, and 10 application-fee variables. Average 1998 USDA alfalfa yield and price data (7.77 Mton•ha^-1 and US$100.33•Mton^-1), plus commercial placebo- and Zn₃P₂-bait costs (US$0.42•kg^-1 and US$2.73•kg^-1), served as the point of comparison. Effects were transitive, with greater net savings and benefit:cost ratios linked with larger field-size, crop-damage and bait-effectiveness variables, but decreased bait-application fees. Potential net savings were essentially negative when damage was <10%. Minimum and maximum benefit:cost ratios were 0.40 and 6.45; ratios ≥2.0 occurred typically when damage was ≥15%. The utility of the illustration and the approach are discussed.

ECONOMIC CONSIDERATIONS OF DAMAGE ASSESSMENT

Richard M. Engeman — Thu, 08 Feb 2007 12:10:37 PST

Cost-effectiveness is the fundamental economic test of any damage control or damage mitigation strategy, and damage assessment is the essential component for determination of cost-effectiveness. However, there are many potential costs associated with making damage assessments. The sampling and measurement required to produce a damage assessment have associated effort and costs, but even greater costs can be incurred due to inappropriate management decisions resulting from inaccurate damage assessments. Other costs can result from using an assessment method that is unsuited to management objectives, or by misinterpreting or not understanding the relationship between observed damage and actual losses. The concepts of sampling, measuring and estimating damage for producing relevant inferences and management decisions are examined with the aid of a variety of examples and simulations.

THE ENDANGERED SPECIES ACT AND PRIVATE LANDOWNER INCENTIVES

Jeffrey A. Michael — Thu, 08 Feb 2007 12:09:33 PST

While intended to increase the habitat available to endangered species, the restrictions of the Endangered Species Act (ESA) increase the costs of harboring an endangered species to private landowners and create incentives for private landowners to reduce habitat. This paper illustrates the incentive for habitat destruction with a simple model of private land use under the ESA, and uses it to predict the effects of changes in policy or biological conditions on private landowner incentives. Many anecdotal accounts and recent empirical research support the predictions of the model. Because of the ESA’s perverse incentives, many have proposed replacing the punitive regulations of the ESA with positive incentives for habitat creation, including takings compensation, negligence compensation rules, tradable development rights, and land purchase programs. The paper concludes by reviewing economic analysis of these proposals’ effectiveness.

DAMAGE ABATEMENT AND COMPENSATION PROGRAMS AS INCENTIVES FOR WILDLIFE MANAGEMENT ON PRIVATE LAND

Jonathan K. Yoder — Thu, 08 Feb 2007 12:08:28 PST

Public damage abatement and compensation programs may be used to alter private incentives for damage abatement and habitat provision. A model is developed that explains the economic logic behind prevalent characteristics of public wildlife damage programs. The model is supported with an examination of a broad cross-section of wildlife agency policy and law. The model can be used by wildlife managers and policy makers as a conceptual framework for understanding the incentive effects of compensation and abatement policy.