Quantifying Eradication Success: the Removal of Feral Pigs from Santa Cruz Island, California

Abstract:  A major challenge facing pest-eradication efforts is determining when eradication has been achieved. When the pest can no longer be detected, managers have to decide whether the pest has actually been eliminated and hence to decide when to terminate the eradication program. For most eradication programs, this decision entails considerable risk and is the largest single issue facing managers of such programs. We addressed this issue for an eradication program of feral pigs ( Sus scrofa ) from Santa Cruz Island, California. Using a Bayesian approach, we estimated the degree of confidence in the success of the eradication program at the point when monitoring failed to detect any more pigs. Catch-effort modeling of the hunting effort required to dispatch pigs during the eradication program was used to determine the relationship between detection probability and searching effort for different hunting methods. We then used these relationships to estimate the amount of monitoring effort required to declare eradication successful with criteria that either set a threshold for the probability that pigs remained undetected (type I error) or minimized the net expected costs of the eradication program (cost of type I and II errors). For aerial and ground-based monitoring techniques, the amount of search effort required to declare eradication successful on the basis of either criterion was highly dependent on the prior belief in the success of the program unless monitoring intensities exceeded 30 km of searching effort per square kilometer of search area for aerial monitoring and, equivalently, 38 km for ground monitoring. Calculation of these criteria to gauge the success of eradication should form an essential component of any eradication program as it allows for a transparent assessment of the risks inherent in the decision to terminate the program.     

THIRD WORLD ENERGY OPTIONS AND THE ROLE OF THE SOLAR ENERGY RESEARCH INSTITUTE

Developing countries are now in a position to choose between further commitments to petroleum and development of sustainable solar resources. Many solar options are ready and some are already economically competitive, particularly for use in rural areas where most people in developing countries reside. Third World countries are becoming cautious about imitating industrial nations, and in some cases, are beginning to map out unique strategies based on their indigenous cultures and resources. Transitions to solar technologies will not be made without difficulty, however, as baseline data on energy needs and on availability of renewable forms of energy only marginally exist. This paper presents information on the potential and current status of a range of solar technologies. The United States Solar Energy Research Institute (SERI) is advancing a number of technologies that will have direct impact on life in developing countries; but in addition has established a programme to deal specifically with the use of renewable energy resources in developing countries. Technical development, planning, information compilation, and institution building are fundamental parts of the effort. As a research institute, SERI, in particular, wants to ensure that adequate attention is given to the technical problems associated with the use of renewables in developing countries. Too often, these problems are not recognized as being worthy of scientific attention resulting in the design and installation of less than optimal equipment. The limited resources available require optimal allocation and intelligent application. In addition, SERI manages bilateral assistance programmes with developing countries under the auspices of the US Department of Energy and the US Agency for International Development. Les pays en développement ont maintenant la possibilité de choisir entre un système basé sur le pétrole ou la mise en valeur des ressources solaires potentielles. Plusieurs systèmes de récupération de l'énergie solaire sont utilisables et quelques-uns sont déjà économiquement compétitifs, particulièrement dans les régions rurales où se rencontre la majeure partie de la population des pays en développement. Les pays du Tiers Monde exercent de plus en plus une certaine prudence à imiter les pays industriels et, dans certains cas, commencent à formuler des stratégies basées uniquement sur leurs ressources et cultures propres. Cependant, le passage à l'énergie solaire ne se fera pas sans difficulté étant donné que les données de base sur les besoins énergétiques et sur la disponibilité des formes renouvelables d'énergie sont marginales. Cet article donne des informations sur le potentiel et l'état actuel de toute une gamme de technologies solaires. L'Institut de recherche d'énergie solaire (IRES) des Etats-Unis est en train de promouvoir un certain nombre de technologies qui auront une portée directe sur le mode de vie dans les pays en développement. II a aussi élaboré un programme spécial concernant l'utilisation des ressources énergétiques renouvelables dans les pays en développement. Le développement technique, la planification, le rassemblement de l'information et la mise en place d'institutions représentent des composantes fondamentales de cet effort. En tant qu'institut de recherche, IRES en particulier voudrait s'assurer que les problèmes techniques concernant l'utilisation des énergies renouvelables dans les pays en développement soient étudiés sérieusement. Trop souvent ces problèmes ne sont pas reconnus comme méritant une étude scientifique ce qui entraîne la conception et la construction d'un équipement qui n'est pas le meilleur. Les ressources disponibles étant limitées, elles requièrent une répartition optimale ainsi qu'une utilisation intelligente. De plus, IRES dirige des programmes d'assistance bilatérale avec les pays en développement sous les auspices du Département de l'énergie et de l'Agence pour le développement international des Etats-Unis. Los países en desarrollo están ahora en la posibilidad de escoger entre una mayor dependencia del petróleo y el desarrollo de energía solar. Muchas alternativas de uso de energía solar están disponibles y algunas son economicamente competitivas, especialmente en las zonas rurales donde reside la mayor parte de la población de los países en desarrollo. Los países del tercer mundo están mas cautos en imitar los países industrializados, y en algunos casos, están empezando a establecer estrategias basadas en su cultura autóctona y sus recursos. Sin embargo la transición a la tecnología solar no va a ser fácil puesto que la información básica sobre las necesidades de energía y la disponibilidad de recursos renovables es muy escasa. Este artículo examina el potencial y la situación actual de las tecnologías de aplicación de energía solar. En los Estados Unidos, el Instituto de Investigación de Energía Solar (IIES) esta proponiendo ciertas tecnologías que tendrán impacto directo sobre la vida en los países en desarrollo, adicionalmente ha establecido un programa para tratar especificamente el uso de recursos renovables de energía en países en desarrollo. Desarrollo técnico, planificación, procesamiento de información y organización de instituciones son partes fundamentales de este esfuerzo. EL IIES quiere asegurar que se dé adecuada atención a los problemas técnicos relacionados con el uso de recursos renovables en los países en desarrollo. A menudo estos problemas se consideran como no importantes para ser objeto de investigación científica y como resultado se diseñan e instalan equipos que no son óptimos. Sin embargo los recursos limitados requieren que se hagan asignaciones óptimas de recursos y aplicaciones inteligentes. Además, el IIES administra programas de asistencia bilateral con los países en desarrollo bajo los auspicios del Departamento de Energía y la Agencia para el Desarrollo Internacional de los Estados Unidos de América.     

MAPPING TROPICAL DEFORESTATION IN CENTRAL AFRICA

The NASA Landsat Pathfinder Humid Tropical Deforestation Project was to map deforestation activities in the humid tropics using datasets from both the Landsat TM (Thematic Mapper) and MSS (Multispectral Scanner System). In Central Africa, its effort had been constrained by the availability of cloud-free satellite coverage, especially for the 1970s Landsat MSS imagery. Here, we reported the deforestation rate and its spatial variability in the region using 18 pairs of co-registered Landsat TM imagery from the 1980s to 1990s. Of the total classified area of 416000 km, there were approximately 217000 km² of dense forest and 24000 km² of degraded forest in the 1980s. A total of 1012 km² of forest, including 542 km² of dense forest and 470 km² of degraded forest, were cleared annually with an annual deforestation rate of 0.42%, varying among scenes ranging from 0.03 to 2.72%. Additionally, an average of 0.12% (ranging from 0.01 to 0.77% among scenes) or 257 km² of dense forest was degraded annually. Regression analyses indicated that extensive deforestation occurred in areas with larger forest cover, including dense and degraded forests. Image interpretation also confirmed the hypothesized relationship between deforestation and forest accessibility. The annual clearance of the dense forest was significantly related to the rural population density, and there was a positive relationship between the dense forest degraded during the 1980s–1990s and the degraded forest area in the 1980s.