The Child Adoption Marketplace: Parental Preferences and Adoption Outcomes

In the United States child adoption costs vary considerably, ranging from no out-of-pocket expense to $50,000 or more. What are the causes for the variability in adoption expenses? We administered a survey to a sample of Michigan adoptive families to link adoptive parent characteristics, child characteristics, and adoption-related expenses and subsidies. We then estimate “hedonic” regressions in which adoption cost is a function of child characteristics. The analysis shows that most of the variation in adoption costs is explained by child characteristics. In particular, costs lower for older children, children of African descent, and special needs children. Findings inform policies regarding the transition of children from foster care to adoptive families.child welfare, adoption, subsidy

Marine biological diversity : report of a meeting of the Marine Biological Diversity Working Group

On August 3 - 4, 1989, the Marine Policy Center of Woods Hole Oceanographic Institution hosted the initial meeting of the Marine Biological Diversity Working Group. The formation of this working group was fostered as part of an ongoing program of research concerning the oceans and biological diversity. Participants in the working group included professionals from the fields of biology, ecology, economics, statistics, law, environmental management, and international assistance, all of whom have expressed an interest in issues surrounding the conservation of marine biological resources. The proposed goals of the working group are to initiate an ongoing interdisciplinary dialogue on the topic, to establish a mechanism for two-way transfer of theory and empirical results between natural and social science, and to serve as a resource for policymakers by providing authoritative and timely information on important issues. This report contains information about the working group and the motivations for its formation, a description of the format of the initial meeting, key points from each of the sessions, abstracts of research/issue briefings delivered at the meeting by participants, selected excerpts from group discussions, and an amended version of a draft working group statement that was introduced to the group for purpose of discussion. The appendices contain the agenda of the meeting, a list of the names and addresses of working group participants, and a list of key questions and issues submitt before the meeting by the working group.Funding was provided by The Pew Charitable Trusts

The Ghost of Extinction: Preservation Values and Minimum Viable Population in Wildlife Models

The inclusion of a minimum viable population in bioeconomic modeling creates at least two complications that are not resolved by using a modified logistic growth function. The first complication can be dealt with by choosing a different depensational growth function. The second complication relates to the inclusion of the in situ benefits of wildlife into the analysis. Knowledge about the magnitude of the in situ benefits provides no guide for policy about conservation management. Simply knowing that people are willing to pay a large amount each year to protect a species says nothing about whether one should manage habitat to protect or enhance the species numbers, unless the species is in imminent danger of extinction. If willingness to pay is to be a guide, it needs to be better tied to population numbers, especially the minimum viable population.marginal willingness to pay, endangered species and extinction, minimum viable population, Resource /Energy Economics and Policy, Q20, Q24, C61,

Anthropogenic and Natural Determinants of the Population of a Sensitive Species: Sage Grouse in Nevada

This paper uses Nevada data to conduct regression analyses of the relationship between sage grouse (Centrocercus urophasianus) population sizes and potential causal factors. This is policy-relevant because of current petitions for listing this species under the Endangered Species Act. A key feature is that, although monitoring of sage grouse has occurred for many decades, data collection methods and level of monitoring effort have not been consistent. To account for this feature we use, as dependent variables, standardized measures such as population counts and harvest (hunting success) per unit of effort. Preliminary findings suggest that such measures have been particularly sensitive to whether or not humans used strychnine for predator control, with normalized measures of grouse populations higher in years when strychnine was employed. Our results also suggest a positive association between the number of cattle on the range and normalized measures of grouse population. This is a controversial finding as some studies suggest a negative impact of cattle grazing on grouse. Our data do not include indications of the timing and precise nature of grazing practices and so should be interpreted with caution.population viability analysis and endangered species, factors affecting decline of sage grouse

Dynamic Programming and Learning Models for Management of a Nonnative Species

Nonnative invasive species result in sizeable economic damages and expensive control costs. Because dynamic optimization models break down if controls depend in complex ways on past controls, non-uniform or scale-dependent spatial attributes, etc., decision support systems that allow learning may be preferred. We compare three models of an invasive weed in California’s grazing lands: (1) a stochastic dynamic programming model, (2) a reinforcement-based, experience-weighted attraction (EWA) learning model, and (3) an EWA model that also includes stochastic forage growth and penalties for repeated application of environmentally harmful control techniques. Results indicate that EWA learning models may be appropriate for invasive species management.Invasive weed species, optimal control, adaptive management

Prevention or Control: Optimal Government Policies for Invasive Species Management

We present a conceptual, but empirically applicable, model for determining the optimal allocation of resources between exclusion and control activities for managing an invasive species with an uncertain discovery time. This model is used to investigate how to allocate limited resources between activities before and after the first discovery of an invasive species and the effects of the characteristics of an invasive species on limited resource allocation. The optimality conditions show that it is economically efficient to spend a larger share of outlays for exclusion activities before, rather than after, a species is first discovered, up to a threshold point. We also find that, after discovery, more exclusionary measures and fewer control measures are optimal, when the pest population is less than a threshold. As the pest population increases beyond this threshold, the exclusionary measures are no longer optimal. Finally, a comparative dynamic analysis indicates that the efficient level of total expenditures on preventive and control measures decreases with the level of the invasive species stock and increases with the intrinsic population growth rate, the rate of additional discoveries avoided, and the maximum possible pest population.invasive species, exclusion, control, eradication, public expenditures, Environmental Economics and Policy, Resource /Energy Economics and Policy,

Economic Impacts of Yellow Starthistle on California Ranchers

While the significant ecosystem damage caused by invasive weeds has been well documented, the economic impacts of specific invasive weed species are poorly understood. Yellow starthistle (Centaurea solstitialis L., hereafter YST) is the most widespread non-crop weed in California, resulting in serious damage to forage on natural range and improved pasture. A survey was administered to California cattle ranchers to investigate YST infestation rates, loss of forage quantity and value, and control or eradication efforts. The results were used to estimate county-wide economic losses for three focus counties, as well as state-wide economic losses, due to YST in California. Total losses of livestock forage value due to YST on private land for the state of California are estimated at $7.96 million/year, with ranchers’ out-of-pocket expenditures on YST control amounting to$9.45 million/year. Together, these costs are the equivalent of 6-7% of the total annual harvested pasture value for the state. Therefore, while the impacts are relatively small within the statewide total agricultural production system, costs due to YST infestation significantly constrain California’s livestock grazing sector.nonnative species, invasive weeds, yellow starthistle, ranching profitability, forage, livestock

THE PLIGHT OF CRANES: A CASE STUDY FOR CONSERVING BIODIVERSITY

Cranes provide an exemplary case for evaluating conservation policy because (1) they are a charismatic group with high public visibility, (2) as migratory vertebrates they provide an umbrella for the protection of aquatic habitats and a wider set of species, (3) they are a widely-distributed avian family, consequently protection efforts have favored international cooperation, (4) genetic and taxonomic relationships have been studied, and (5) populations of at least 7 crane species are threatened, endangered, or otherwise considered at direct risk. We use comparisons among the world\u27s cranes to show how biogeographic, taxonomic, and genetic data bases can be linked for conservation decisions. We show that decisions typically faced by a conservation planner are themselves diverse (e.g., choosing species for captive propagation, or identifying priority habitats for maintaining taxonomic distinctiveness), thereby obviating the utility of any single, all-purpose measure of diversity. Conservation priorities are shown to change with successive informational input regarding phylogenetic relationships, extinction risks, and popUlation trends, and to differ greatly from priorities based on species richness alone

Managing Nonindigenous Invasive Species: Insights from Dynamic Analysis

Accidental introductions of nonindigenous invasive species impair ecosystems, increase the risk of native species extinctions, and cause substantial economic damages on a worldwide basis. Despite the magnitude of the problem, very little economic analysis has been focused on this topic to date. This manuscript develops an optimal control model of the management of a nonindigenous species stock following its introduction and establishment. We find that the influence of changes in ecological and human factors (such as the invader's intrinsic growth rate, carrying capacity, and the effectiveness of invasive species management technologies) on the optimal level of management are analytically (mathematically) ambiguous in sign and depend on the values of other parameters and variables. To estimate actual numerical solutions to the model and conduct sensitivity analyses, we construct a case study illustration based on invasive plant species on arid lands. The illustration shows that the optimal level of management effort is sensitive to biological and ecological factors (the stock's intrinsic rate of growth, the carrying capacity afforded the invasive species, and the form of the invader's growth function) that are species- and site-specific as well as uncertain given currently available scientific information. This highlights the need for better collaboration and information transfer between economists and scientists interested in this topic. Given that resources for addressing nonindigenous species threats typically are quite constrained, and complete eradication in a particular area is often technically infeasible, the model provides useful insight on optimal levels of ongoing management and how they may vary according to bioeconomic factors. Copyright Kluwer Academic Publishers 2002bioeconomic modeling, biological invasions, invasive species, nonindigenous species, optimal control,

Using Dynamic Optimization for Integrated Environmental Management: An Application to Solvent Waste Disposal

The choice of disposal strategy for a residuals stream often determines the environmental medium into which the pollution is released. In turn, choice of medium may influence both the kinds of adverse effects that the pollution will have and the timing of those effects as well. As an illustration of the way in which these factors may be taken into account in integrated environmental management, this paper demonstrates the application of a dynamic optimization model to the problem of allocating a pollutant between two different disposal methods. The alternatives examined are incineration and land disposal for metal-bearing solvent waste.