Abstract: Subsistence game hunting has profound negative effects on the species diversity, standing biomass, and size structure of vertebrate assemblages in Amazonian forests that otherwise remain largely undis- turbed. These effects are likely to be considerably aggravated by forest fragmentation because fragments are more accessible to hunters, allow no (or very low rates of ) recolonization from nonharvested source popula- tions, and may provide a lower-quality resource base for the frugivore-granivore vertebrate fauna. I exam- ined the likelihood of midsized to large-bodied bird and mammal populations persisting in Amazonian forest fragments of variable sizes whenever they continue to be harvested by subsistence hunters in the aftermath of isolation. I used data from a comprehensive compilation of game-harvest studies throughout Neotropical for- ests to estimate the degree to which different species and populations have been overharvested and then cal- culated the range of minimum forest areas required to maintain a sustainable harvest. The size distribution of 5564 Amazonian forest fragments—estimated from Landsat images of six regions of southern and eastern Brazilian Amazonia—clearly shows that these are predominantly small and rarely exceed 10 ha, suggesting that persistent overhunting is likely to drive most midsized to large vertebrate populations to local extinction in fragmented forest landscapes. Although experimental studies on this negative synergism remain largely unavailable, the prospect that increasingly fragmented Neotropical forest regions can retain their full assem- blages of avian and mammalian species is unlikely.

Abstract: Policies to reduce global warming by offering credits for carbon sequestration have neglected the effects of forest management on biodiversity. I review properties of forest ecosystems and management op- tions for enhancing the resistance and resilience of forests to climate change. Although forests, as a class, have proved resilient to past changes in climate, today's fragmented and degraded forests are more vulnerable. Ad- aptation of species to climate change can occur through phenotypic plasticity, evolution, or migration to suit- able sites, with the latter probably the most common response in the past. Among the land-use and manage- ment practices likely to maintain forest biodiversity and ecological functions during climate change are (1) representing forest types across environmental gradients in reserves; (2) protecting climatic refugia at multi- ple scales; (3) protecting primary forests; (4) avoiding fragmentation and providing connectivity, especially parallel to climatic gradients; (5) providing buffer zones for adjustment of reserve boundaries; (6) practicing low-intensity forestry and preventing conversion of natural forests to plantations; (7) maintaining natural fire regimes; (8) maintaining diverse gene pools; and (9) identifying and protecting functional groups and keystone species. Good forest management in a time of rapidly changing climate differs little from good forest management under more static conditions, but there is increased emphasis on protecting climatic refugia and providing connectivity.

Abstract: Practical conservation activity is increasing globally and is being undertaken by many different government and nongovernmental organizations. In the majority of cases, justification for proposed actions is experience-based rather than evidence-based, action is often taken without monitoring or evaluation of effectiveness, and results are rarely widely disseminated. Conservation has been compared with medicine as a crisis discipline in which action is often required urgently in the absence of good information. The practice of medicine has recently gone through an effectiveness revolution that has improved the criteria upon which treatment strategies are based by progressing from reliance on personal experience to reliance on scientific evidence. We draw parallels between medicine and conservation and present a practical framework to encourage evidence-based conservation action. Our rationale is that conservation actions for which scarce resources are sought should be justified by good scientific evidence. In our view this will also encourage more research addressing practical issues in conservation management.

Abstract: The Amazon basin is experiencing rapid forest loss and fragmentation. Fragmented forests are more prone than intact forests to periodic damage from El Nino–Southern Oscillation ( ENSO) droughts, which cause elevated tree mortality, increased litterfall, shifts in plant phenology, and other ecological changes, especially near forest edges. Moreover, positive feedbacks among forest loss, fragmentation, fire, and regional climate change appear increasingly likely. Deforestation reduces plant evapotranspiration, which in turn constrains regional rainfall, increasing the vulnerability of forests to fire. Forest fragments are especially vulnerable because they have dry, fire-prone edges, are logged frequently, and often are adjoined by cattle pastures, which are burned regularly. The net result is that there may be a critical “deforestation threshold” above which Amazonian rainforests can no longer be sustained, particularly in relatively seasonal areas of the basin. Global warming could exacerbate this problem if it promotes drier climates or stronger ENSO droughts. Synergisms among many simultaneous environmental changes are posing unprecedented threats to Amazonian forests.

Abstract: Conservation biologists, policy makers, and citizens have identified the protection of native ecosystems in low-income nations as a global social objective. Among the more popular initiatives toward this objective is the use of development interventions in the peripheral areas of endangered ecosystems. Such interventions indirectly provide desirable ecosystem services by redirecting labor and capital away from activities that degrade ecosystems (e.g., agricultural intensification) and by encouraging commercial activities that supply ecosystem services as joint products (e.g., ecotourism). I examined the economics of such interventions and the available empirical evidence and concluded that development interventions are hindered by (1) the indirect and ambiguous conservation incentives that they generate, (2) the complexity of their implementation, and (3) their lack of conformity with the temporal and spatial dimensions of ecosystem conservation objectives. In contrast, paying individuals or communities directly for conservation performance may be a simpler and more effective approach. In recent years there has been widespread experimentation with contracting approaches to ecosystem conservation. Conservation contracting can (1) reduce the set of critical parameters that practitioners must affect to achieve conservation goals, (2) permit more precise targeting and more rapid adaptation over time, and (3) strengthen the links between individual well-being, individual actions, and habitat conservation, thus creating a local stake in ecosystem protection. In situations where performance payments are unlikely to work, indirect development interventions are also unlikely to work. Thus, despite the potential barriers to developing a system of conservation contracts in low-income nations, my analysis suggests that performance payments have the potential to improve the way in which ecosystems are conserved in these nations. Resumen: Los biologos conservacionistas, los legisladores y los ciudadanos han identificado la proteccion de ecosistemas en naciones con bajos ingresos como un objetivo social global. Entre las iniciativas mas populares para alcanzar este objetivo se encuentra el uso de intervenciones para el desarrollo en areas perifericas de ecosistemas en peligro. Estas intervenciones proveen servicios deseables del ecosistema indirectamente al re-direccionar actividades y capital lejos de las actividades que degradan el ecosistema ( por ejemplo, intensificacion agricola) y alentando actividades comerciales que provean servicios del ecosistema como los productos de coyuntura ( por ejemplo, ecoturismo). Examine la economia de estas intervenciones los y las evidencias empiricas disponibles y conclui que las intervenciones de desarrollo son entorpecidas por (1) incentivos indirectos y ambiguos que generan; (2) la complejidad de su implementacion y (3) la carencia de concordancia con las dimensiones temporales y espaciales de los objetivos de conservacion del ecosistema. En contraste, el pago directo a individuos o comunidades por la ejecucion de la conservacion podria ser una estrategia mas simple y mas efectiva. En anos recientes, ha habido amplia experimentacion con las estrategias de contratacion para la conservacion de ecosistemas. Los contratos para conservacion pueden (1) reducir el conjunto de parametros criticos que los practicantes deben afectar para alcanzar las metas de conservacion; (2) permitir el establecimiento de metas mas precisas; y (3) fortalecer los vinculos entre el bienestar individual, las acciones individuales y la conservacion del habitat, creando asi un interes local en la proteccion del ecosistema. En situaciones donde los pagos por rendimiento no son viables de funcionar, las intervenciones de desarrollo indirecto probablemente tampoco funcionen. Por ello, a pesar de las barreras potenciales al desarrollo de desarrollar un sistema de contratos de conservacion en naciones de bajos recursos, mi analisis sugiere que los pagos por rendimiento tienen el potencial para mejorar la forma en la que los ecosistemas son conservados en estas naciones.

Abstract: Vehicular traffic can be a major source of mortality for some species. Highly vagile organisms may be at a disadvantage in landscapes with roads because they are more likely to encounter roads and incur traffic mortality. To test this prediction, we assessed the population abundance of two anuran species of dif- fering vagility, the leopard frog ( Rana pipiens , more vagile) and the green frog ( Rana clamitans , less vagile), at 30 breeding ponds. Traffic density, an index of the amount of potential traffic mortality, was measured in concentric circles radiating from the ponds out to 5 km. We conducted multiple linear regressions relating population abundance to traffic density, pond variables, and landscape habitat variables and found that leopard frog population density was negatively affected by traffic density within a radius of 1.5 km. There was no evidence that the presence of vehicular traffic affected green frog populations. These results suggest that traffic mortality can cause population declines and that more vagile species may be more vulnerable to road mortality than less vagile species.

Abstract: Infectious and noninfectious diseases are being recognized by conservation biologists as an increasing challenge to the conservation of wildlife. The amplified role of diseases as a factor limiting species' survival can be traced to anthropogenic changes on a global scale that have direct and indirect influences on the health of wildlife species. These changes include human population growth, habitat fragmentation and degradation, the isolation of populations of species, and an increased proximity of humans (and their domestic animals) to wildlife. Further, some conservation projects have caused more harm than good by unwittingly introducing diseases to wildlife populations, whereas others have failed to meet their objectives because they did not take disease factors into consideration. Conservation biologists need to move quickly past the decades-old debate on the relative importance of wildlife health to conservation and begin using all the tools available to ensure the effectiveness of their efforts. We briefly review the literature on wildlife diseases, place wildlife health in the context of global changes affecting wild animal populations, and offer concrete suggestions for ways to integrate wildlife health sciences into conservation, such as including health assessment or monitoring programs and research on interspecies disease transmission in field biology projects, training wildlife professionals in the design and implementation of wildlife studies that incorporate health components, and encouraging interdisciplinary collaboration. Our goal is to raise awareness that conservation biologists working in disciplines ranging from field biology to policy making have an important role to play in facilitating a transition toward a new conservation paradigm that includes wildlife health. This paradigm shift will take an academic understanding of the importance of wildlife disease and turn it into practical actions that will help conserve wildlife more effectively. Resumen: Los biologos de la conservacion reconocen que las enfermedades infecciosas y no infecciosas son un reto cada vez mayor para la conservacion de vida silvestre. El papel de las enfermedades como un factor limitante de la sobrevivencia de especies se puede deber a cambios antropogenicos a escala global que tienen influencia directa e indirecta en la salud de especies de vida silvestre. Estos cambios incluyen el crecimiento de la poblacion, la fragmentacion y degradacion del habitat, el aislamiento de poblaciones y una mayor proximidad de humanos ( y sus animales domesticos) a la vida silvestre. Adicionalmente, algunos proyectos de conservacion han causado mas danos que beneficios al introducir, inconscientemente, enfermedades en las poblaciones de vida silvestre, mientras que otros han fallado en alcanzar sus objetivos porque no tomaron en consideracion a factores de enfermedades. Como biologos de la conservacion, necesitamos rapidamente superar el debate que se ha dado por decadas sobre la importancia relativa de la salud de la vida silvestre para la conservacion y comenzar a utilizar todas las herramientas disponibles para asegurar la efectividad de nuestros esfuerzos. Brevemente examinamos la literatura sobre enfermedades de vida silvestre, colocamos la salud de la vida silvestre en un contexto de cambios globales que afectan poblaciones silvestres de animales y ofrecemos sugerencias concretas para integrar las ciencias de la salud de vida silvestre en la conservacion, como incluir la evaluacion de la salud o programas de monitoreo e investigar la transmision de enfermedades entre especies en proyectos de campo, entrenar profesionales de la vida silvestre en el diseno e instrumentacion de estudios de vida silvestre que incorporen componentes de salud y colaboracion trans-disciplinaria. Nuestra meta es crear conciencia de que los biologos de la conservacion que trabajan en disciplinas que van de la biologia de campo a definicion de politicas juegan un papel importante en la transicion hacia un nuevo paradigma de conservacion que incluye la salud de la vida silvestre. Este cambio de paradigma tendra el entendimiento de la academia acerca de la importancia de las enfermedades de la vida silvestre y transformarlo en acciones practicas que ayudaran a conservar a la vida silvestre mas eficientemente.

Abstract: Conservation Biology, Pages 7–20 Volume 15, No. 1, February 2001 This paper is a much abridged version of World Bank Environment Department Paper 75, “Biodiversity Conservation in the Context of Tropical Forest Management,” by the same authors. It is the first paper in the bank’s Impact Studies Series, which addresses the broader questions of the positive and negative effects of human activities on biodiversity. A more complete set of data supporting the arguments herein are in the appendices and text of the World Bank paper, which can be accessed from http://www.worldbank.org/biodiversity.

Abstract: Forest fragmentation leads to a dramatic increase in forest edge, and these edges may function as traps and concentrators for wind-borne nutrients and pollutants. We assessed the influence of forest edges on atmospheric deposition and subsequent inputs to the forest floor in deciduous-forest fragments in the eastern United States. To quantify these inputs, we collected throughfall—water that has passed through the forest canopy—from edge and interior zones of forests adjacent to open fields. During the 1995 growing season, atmospheric input (wet and dry deposition) of sulfur to forest edge zones was elevated compared with input to forest interiors. Throughfall fluxes of dissolved inorganic nitrogen and calcium were also greater at edges than interiors. The mean edge increases ranged from 17% to 56% for the nutrients and pollutants we measured. When we manipulated the structure of forest edges by removing all vegetation below half the canopy height, throughfall flux in the edge zone declined sharply and was less than that of the respective interior zone. Changing the vegetation structure of the edge also shifted the zone of highest throughfall flux farther into the interior of the forest. Our data suggest that forest edges can function both as significant traps for airborne nutrients and pollutants from adjoining agricultural or urban landscapes and effective concentrators of below-canopy chemical fluxes. These enhanced fluxes may have cascading effects on soil-nutrient cycling, microbial activity, seedling dominance, and other ecological processes near forest edges.

Abstract: The growing prevalence of fragmentation and fire in tropical forests makes it imperative to quantify changes in these disturbances and to understand the ways in which they interact across the landscape I used a multitemporal series of Landsat images to study the incidence and coincidence of fire and fragmentation in two areas of Para state in the eastern Brazilian Amazon: Tailândia and Paragominase In both areas, deforestation and forest fires were quantified for time series of 6–10 years The Tailândia study area typifies a landscape with the herringbone pattern of government-settled colonists, and the Paragominas area is dominated by large cattle ranches In both areas, over 90% of the forests affected by fire were associated with forest edges Although most burned forest occurred within 500 m of forest edges, some fires occurred in deep forest, several kilometers from any edge The obvious synergism between forest fragmentation and fire poses serious risks to tropical ecosystems and has important implications for land management Resumen: La creciente prevalencia de la fragmentacion y los incendios en bosques tropicales hacen imprescindible cuantificar los cambios en estas perturbaciones y entender las formas en las que estos interactuan a lo largo del paisaje Utilice series multitemporales de imagenes de Landsat para estudiar la incidencia de incendios y la coincidencia de estos con la fragmentacion en dos areas del Estado de Para en la Amazonia Brasilena del Este: Tailâ·ndia y Paragominase En ambas areas, la deforestacion y los incendios forestales fueron cuantificados para series de tiempos de 6–10 anos El area de estudio de Tailâ·ndia tipifica un paisaje con un patron de ‘hueso de arenque’ poblado por colonizadores establecidos por el gobierno, mientras que el area de Paragominas esta dominada por establecimientos ganaderos grandes En ambas areas, mas del 90% de los bosques afectados por incendios estuvieron asociados con los bordes del bosque Aunque la mayoria de los bosques quemados se encontraban a menos de 500 m de la orilla del borde, algunos incendios ocurrieron en la profundidad del bosque, a varios kilometros adentro de cualquier borde El sinergismo obvio entre la fragmentacion del bosque y los incendios presenta serios riesgos para los ecosistemas tropicales y tiene implicaciones importantes para el manejo de la tierra

Abstract: This paper represents a work in progress by the World Conservation Union (IUCN). Earlier drafts of the work have appeared in IUCN publications, but the “International Issues” section of Conservation Biology seems an appropriate and important place to publish the penultimate version of the document. Comments on this issue in general or on the approach taken by the IUCN should be sent to the authors directly. Joshua Ginsburg

Abstract: The African elephant ( Loxodonta africana ) experienced a poaching-related 60% population decline between 1979 and 1988 that was inordinately concentrated on adults. This, coupled with political pressures to delist the elephant, has created a need for noninvasive physiological measures that can quantify the long- term effects of past mortality patterns of this long-lived species. We collected fresh fecal samples from 16 female elephants in three different groups over 23 months at Tarangire National Park, Tanzania, and analyzed them for fecal progesterone and cortisol metabolites. Social and ecological measures were collected concur- rently. Fecal progesterone metabolite measures corresponded significantly with stage of gestation, and appear to be able to confirm pregnancy in female elephants from as early as 3 months of gestation. We found that progesterone metabolite concentrations were significantly lower during the dry season than during the wet season after controlling for stage of gestation. Fecal cortisol metabolite concentrations showed the opposite seasonal pattern, being significantly higher in the dry season and inversely correlated with rainfall across seasons. Fecal cortisol metabolite concentrations also increased with group size and were correlated posi- tively with dominance rank in the largest group. Our results suggest that measures of progesterone and corti- sol metabolites in feces provide indices of reproductive function and physiological stress that can quantify both natural and human disturbances in African elephants. These measures are ideally suited for monitoring the long-term effects of social disruption from poaching and a variety of other management concerns. Estres No Invasivo y Medidas Reproductivas de Presiones Sociales y Ecologicas en Elefantes Africanos Libres Resumen: Debido a la caceria furtiva, la poblacion de elefante africano ( Loxodonta africana ) declino en un 60%, principalmente adultos, entre 1979 y 1988. Esto, aunado a presiones politicas para eliminar al elefante de las listas de especies en peligro, ha creado la necesidad de medidas fisiologicas no invasivas que puedan cuantificar efectos a largo plazo de patrones de mortalidad en el pasado de esta especie longeva. Recolecta- mos muestras fecales de 16 elefantes hembras en tres grupos diferentes en el Parque Nacional Tarangire, Tanzania a lo largo de 23 meses, y las analizamos para detectar metabolitos de progesterona fecal y de corti- sol. Al mismo tiempo se recolectaron medidas sociales y ecologicas. Las medidas de metabolitos de progester- ona fecal correspondieron significativamente con la etapa de gestacion, y parecen permitir la confirmacion de prenez en elefantes hembras tan temprano como a los tres meses de gestacion. Las concentraciones de me- tabolitos de progesterona fueron significativamente menores durante la epoca de sequia que en la de lluvias despues de controlar para la etapa de gestacion. Las concentraciones de metabolitos de cortisol fecal mos- traron un patron estacional opuesto, siendo significativamente mas altas en la epoca de sequia e inversa- mente correlacionados con la precipitacion en todas las estaciones. Las concentraciones de metabolitos de cortisol fecal tambien incrementaron con el tamano del grupo y se correlacionaron positivamente con el rango de dominancia en el grupo mas grande. Nuestros resultados sugieren que las medidas de metabolitos de progesterona y cortisol en las heces proporcionan indices de la funcion reproductiva y del estres fisiologico

Abstract: We analyzed the usefulness of woodpecker species ( family Picidae) in predicting the diversity of other forest bird species using the Polish Ornithological Atlas data on species distribution in Poland. We used the database (n = 2317) to examine the patterns of woodpecker occurrence in atlas plots and to test how well the occurrence of woodpecker species is related to the occurrence of other forest birds. The occupancy of atlas plots by particular species varied from 98.5% in the Great Spotted Woodpecker ( Dendrocopos major) to only 2.4% in the Three-toed Woodpecker ( Picoides tridactylus). Woodpecker species richness in plots varied between 0 and 10 species, with a mean value of 4.3 species per plot. The occurrence of particular woodpecker species in plots with different woodpecker species richness was associated with the degree of specialization in particular species. Examining the entire data set, we found a positive relationship between woodpecker species richness and the number of species of other forest birds. These relationships were confirmed in three smaller regional data subsets with at least eight woodpecker species present (northeast Poland, r 2 = 0.78, p = 0.0001; east Poland, r 2 = 0.53, p = 0.0001; Carpathians, r 2 = 0.53, p = 0.0001). The mean number of forest specialists increased from 6 to over 30 species in plots with 0 and 9 woodpecker species, respectively. Also, the mean number of woodland generalists increased steadily with woodpecker species richness. Our results confirm the suitability of the woodpecker group as part of an indicator system for assessing avian diversity at the landscape scale. We suggest that in countries or regions in Europe where data on bird diversity are not readily available, woodpecker surveys could serve as a good tool for assessing the diversity of forest birds at the landscape scale. Resumen: Analizamos la utilidad de las especies de pajaros carpinteros ( Familia Picidae) en la prediccion de la diversidad de otras aves forestales usando datos de cooperacion del Atlas Ornitologico Europeo sobre la distribucion de especies de Polonia. Usamos la base de datos (n = 2317) para examinar los patrones de presencia en parcelas del atlas y para evaluar que tan bien se relaciona la presencia de los pajaros carpinteros con la presencia de otras especies de aves del bosque. La ocupacion de parcelas del atlas por especies en particular vario desde un 98.5% para el gran pajaro carpintero manchado ( Dendrocopos major) hasta un 2.4% para el carpintero de tres dedos ( Picoides tridactylus). La riqueza de especies de pajaros carpinteros en parcelas vario entre 0 y 10 especies, con un valor promedio de 4.3 especies por parcela. La aparicion de especies especificas de pajaros carpinteros en parcelas con diferente riqueza de especies de pajaros carpinteros estuvo asociada con el grado de especializacion de ciertas especies en particular. Al examinar el juego de datos completo, encontramos una relacion positiva entre la riqueza de especies de pajaros carpinteros y el numero de especies de otras aves del bosque. Estas relaciones fueron confirmadas en tres subgrupos de datos regionales con al menos 8 especies de pajaros carpinteros presentes (Polonia nororiental r 2 = 0.78, p = 0.0001; Polonia oriental r 2 = 0.53, p = 0.0001; Carpatos, r 2 = 0.53, p = 0.0001). El numero promedio de especialistas del bosque se incremento respectivamente de seis a mas de 30 especies en parcelas con cero y nueve especies de pajaros carpinteros. Asimismo, el numero promedio de generalistas del bosque incremento aceleradamente con la riqueza de especies de pajaros carpinteros. Nuestros resultados confirman la viabilidad del grupo de los pajaros carpinteros como parte de un sistema indicador para evaluar la diversidad de aves a escala de paisaje. Sugerimos que en paises o regiones de Europa donde los datos sobre diversidad de aves no son faciles de obtener, se pueden usar reconocimientos de pajaros carpinteros como una buena herramienta para evaluar la densidad de aves del bosque a escala de paisaje.

Abstract: The introduction of alien, or nonindigenous, animals and plants has been identified by scientists and policy makers as a major threat to biodiversity in marine ecosystems. Although government agencies have struggled to control alien species on land and freshwater for decades with mixed success, the control of alien marine species is in its infancy. Prevention of introduction and establishment must be the first priority, but many populations of alien marine species are already well established worldwide. National and interna- tional policies leave loopholes for additional invasions to occur and provide only general guidance on how to control alien species once they are established. To address this issue, a multinational group of 25 scientists and attorneys convened in 1998 to examine options for controlling established populations of alien marine species. The discussions resulted in a framework for control of alien marine species to provide decision-mak- ing guidance to policymakers, managers, scientists, and other stakeholders. The framework consists of seven basic steps: (1) establish the nature and magnitude of the problem, (2) set objectives, (3) consider the full range of alternatives, (4) determine risk, (5) reduce risk, (6) assess benefits versus risks, and (7) monitor the situation. This framework can provide guidance for control efforts under the existing patchwork of national laws and can help provide a foundation for international cooperation.

Abstract: In farmlands, the population viability of many amphibians is suspected to depend on the resistance the matrix of crop fields presents to movements between ponds and terrestrial sites and movements among ponds. Over recent decades the increase in cereal growing at the expense of cattle breeding has caused a drastic change in habitat matrix in many European regions. We investigated the effect of such change on populations of three newt species ( Triturus helveticus, T. alpestris, and T. cristatus) by comparing their abundances in sites that varied in amount of cultivated ground. A multivariate regression analysis of the relationship of newt abundance to both pond and landscape variables demonstrated the negative influence of cultivated ground on abundance. The width of the uncultivated sector linking the pond to the forest was a good predictor of abundance after the influences of both pond area and fish presence were removed. Moreover, newt presence was positively related to the number of ponds within that 50-ha surrounding area, highlighting the role of metapopulation functioning in newt occupancy of ponds. The relationship between newt abundance and width of uncultivated sectors agrees with present knowledge of the orientation mechanisms that underlie migration movements in urodeles. Such a relationship between connectedness and sector width shows that narrow, linear corridors such as hedgerows may not be useful in newt conservation. Our study also highlights the need to incorporate a behavioral component of habitat use into models of connectivity in conservation biology. Resumen: Se considera que en tierras de cultivo la disponibilidad poblacional de muchos anfibios depende de la resistencia que la matriz de las tierras de cultivo presentan a los movimientos entre estanques y los sitios terrestres, y entre estanques. Durante las decadas recientes el incremento en la produccion de cereal a cambio de la cria de ganado ha ocasionado un cambio drastico en la matriz del habitat en muchas regiones de Europa. Investigamos los efectos de estos cambios en las poblaciones de tres especies de tritones ( Triturus helveticus, T. alpestris y T. cristatus) comparando sus abundancias en sitios que variaron en la cantidad de tierra cultivada. Un analisis de regresion multivariado de las relaciones entre la abundancia de tritones y las variables de los estanques y del paisaje demostro las influencias negativas de las tierras de cultivo sobre la abundancia. La amplitud de sectores sin cultivar que conecto a los estanques con el bosque fue un buen pronosticador de la abundancia despues de remover las influencias del area del estanque y la presencia de peces. Mas aun, la presencia de tritones estuvo positivamente relacionada con el numero de estanques dentro de un area adyacente de 50 ha, resaltando el papel del funcionamiento de la metapoblacion en la ocupacion de estanques. La relacion entre la abundancia de tritones y la amplitud de sectores sin cultivar concuerda con el conocimiento actual sobre los mecanismos de orientacion que delimitan los movimientos de migracion en urodelos. Esta relacion entre la conectividad y la amplitud del sector muestra que los corredores estrechos y lineales como lo son los cercos podrian no ser utiles para la conservacion de tritones. Nuestro estudio tambien resalta la necesidad de incorporar un componente conductual del uso del habitat cuando se modela la conectividad en estudios de conservacion biologica.

Abstract: Historical variability in fire regime is a conservative indicator of ecosystem sustainability, and thus understanding the natural role of fire in chaparral ecosystems is necessary for proper fire management. It has been suggested that the "natural" fire regime was one of frequent small fires that fragmented the land- scape into a fine-grained mixture of age classes that precluded large, catastrophic fires. Some researchers claim that this regime was lost because of highly effective fire suppression and conclude that if fire managers could "restore" a regime of frequent fires with widespread prescription burning, they could eliminate the haz- ard of catastrophic fires. The primary evidence in support of this model is a study that compared contempo- rary burning patterns in southern California, U.S.A., a region subject to fire suppression, with patterns in northern Baja California, Mexico, where there is less effective fire suppression. We found that differences in fire regime between these two regions are inconclusive and could not be ascribed conclusively to differences in fire suppression. Historical records suggest that the natural fire regime in southern California shrublands was rather coarse-grained and not substantively different from the contemporary regime. There is no evi- dence that fire-management policies have created the contemporary fire regime dominated by massive Santa Ana wind-driven fires. Increased expenditures on fire suppression and increased loss of property and lives are the result of human demographic patterns that place increasing demand on fire-suppression forces.

Abstract: A commonly held belief is that if people can benefit financially from enterprises that depend on nearby forests, reefs, and other natural habitats, then they will take action to conserve and sustainably use them. The Biodiversity Conservation Network brought together conservation and development organizations and local communities to systematically test this hypothesis across 39 conservation project sites in Asia and the Pacific. Each project implemented one or more community-based enterprises such as setting up an ecotourism lodge, distilling essential oils from wild plant roots, producing jams and jellies from forest fruits, harvesting timber, or collecting marine samples to test for pharmaceutical compounds. Each project team collected the biological, enterprise, and social data necessary to test the network's hypothesis. We present the results of this test. We found that a community-based enterprise strategy can lead to conservation, but only under limited conditions and never on its own. We summarize the specific conditions under which an enterprise strategy will and will not work in a decision chart that can be used by project managers to determine whether this strategy might make sense at their site. We also found that an enterprise strategy can be subsidized and still create a net gain that pays for conservation. Based on our experiences, we recommend developing “learning portfolios” that combine action and research to test other conservation strategies. Resumen: Una creencia comunmente difundida es que la gente se puede beneficiar financieramente de empresas que dependen de bosques, arrecifes, y otros habitats naturales cercanos y por lo tanto llevarian a cabo acciones para conservar y usarlos sostenidamente. La Red de Conservacion de la Biodiversidad junto a organizaciones de conservacion y desarrollo y a comunidades locales para probar sistematicamente esta hipotesis en 39 proyectos de conservacion en sitios de Asia y el Pacifico. Cada proyecto implemento una o mas empresas basadas en la comunidad, tales como el establecimiento de alojamiento para ecoturismo, destilacion de aceites esenciales a partir de raices de plantas silvestres, produccion de jaleas y mermeladas de frutas del bosque, tala de madera, o la colecta de muestras marinas para probar compuestos farmaceuticos. Cada equipo de trabajo colecto los datos biologicos, empresariales y sociales necesarios para probar la hipotesis de la red. Nosotros presentamos aqui los resultados de esta prueba. Encontramos que una estrategia de las empresas basadas en la comunidad puede conducir a la conservacion, pero solo bajo limitadas condiciones y nunca por si sola. Resumimos las condiciones especificas bajo las cuales una estrategia empresarial trabajaria o no en un diagrama de decisiones que puede ser usado por administradores para determinar si esta estrategia tendria sentido para su sitio. Tambien encontramos que una estrategia empresarial puede ser subsidiada y aun crear una ganancia neta que pague por la conservacion. En base a nuestras experiencias, recomendamos desarrollar “portafolios de aprendizaje” que combinen acciones e investigacion para probar otras estrategias de conservacion.

Abstract: It has been suggested that restoration of roadsides to native habitat can benefit wildlife by adding habitat and restoring connectivity between fragmented reserves. In Iowa, which has one of the highest road densities in the United States, roadside vegetation has traditionally been managed to maintain a monoctil- ture of exotic grass. Recently, several Iowa counties have begun integrated roadside vegetation management, a program that both restores roadsides to native prairie vegetation and restricts the use of herbicides and mowing. We eval.uated the effect of this management regime on butterfly populations along central Iowa roadsides. We surveyed 12 separate prairie roadside areas, comparing the abundance and species richness of disturbance-tolerant and habitat-sensitive butterflies in roadside prairies with those of nearby roadsides dominated by either weeds (primarily non-native legumes) or non-native grasses. We found that manage- mnent of roadsides profoutndly affected the butterfly community. Species richness of habitat-sensitive butter- flies showed a two-fold increase in prairie compared with grassy and weedy roadsides (p < 0.0001), and abundance increased almostfive times more on the prairie than on grassy roadsides (p < 0. 02). Species rich- ness of disturbance-tolerant butterflies showed no response to roadside management, although abundance was slightly higher in weedy and prairie roadsides than on grassy roadsides (p < 0.01). Of all habitat vari- ables explored, the species richness ofplants inflower showed the, strongest effect on mean richness and abun- numbers indicated that mortality risk was more than twice as high on grassy roadsides (p < 0.0001). Track- ing studies showved that butterflies were less likely to exit prairie roadsides, indicating that their mortality rates may be lower and offering preliminary evidence that roadsides have the potential to be used as corri- dors. Overall, our results indicate that roadside restoration benefits butterfly populations. More detailed de- mographic data are necessary, however, to explore tle possibility that roadsides are acting as sink habitatfor some habitat-restricted species.

Abstract: Although the poaching of nestlings for the pet trade is thought to contribute to the decline of many species of parrots, its effects have been poorly demonstrated. We calculated rates of mortality due to nest poaching in 23 studies of Neotropical parrots, representing 4024 nesting attempts in 21 species and 14 coun- tries. We also examined how poaching rates vary with geographic region, presence of active protection pro- grams, conservation status and economic value of a species, and passage of the U.S. Wild Bird Conservation Act. The average poaching rate across all studies was 30% of all nests observed. Thirteen studies reported poaching rates of � 20%, and four reported rates of � 70%. Only six studies documented no nest poaching. Of these, four were conducted on islands in the Caribbean region, which had significantly lower poaching rates than the mainland Neotropics. The other two studies that showed no poaching were conducted on the two species with the lowest economic value in our sample (U.S. retail price). In four studies that allowed direct comparison between poaching at sites with active nest protection versus that at unprotected sites, poaching rates were significantly lower at protected sites, suggesting that active protection efforts can be effective in re-

Abstract: Consumption of bushmeat is an important component of household economies in most tropical forested regions of the world and is resulting in unsustainable levels of hunting, even in relatively isolated regions. We conducted standardized surveys of household consumption, income, wealth, and education level among Amerindian societies in Central and South America. Results suggest 1) demand for bushmeat may follow an inverted ∪ pattern with income, 2) consumers, particularly the most well-off, reduce their consumption of bushmeat as the price increases; and 3) a small decrease in the price of meat from domesticated animals is likely to lead to a large decrease in the consumption of fish but not of bushmeat. Policy makers may be able to reduce demand for bushmeat by raising the price of bushmeat, by increasing the direct and opportunity costs of hunting, and by raising household income. Resumen: El consumo de carne silvestre es un componente importante de las economias caseras en la mayoria de las regiones tropicales boscosas del mundo y esta resultando en niveles insostenibles de caza, aun en regiones relativamente aisladas. Llevamos a cabo prospecciones estandarizadas de consumo familiar, riqueza y niveles de educacion entre sociedades Amerindias en America del Sur y Central. Los resultados sugieren que 1) la demanda de carne silvestre podria seguir un patron de ∪ invertido con los ingresos; 2) los consumidores, particularmente la mayoria de los persistentes, reducen el consumo de carne silvestre en tanto que el precio aumenta; y 3) una disminucion pequena en el precio de carne de animales domesticados es posible que conduzca a una disminucion grande en el consumo de peces, pero no de carne de animales silvestres. Los politicos deberian de reducir la demanda de carne silvestre incrementando su precio, incrementando los costos directos y de oportunidad de la caza e incrementando los ingresos familiares.

Abstract: We investigated the habitat use and movements of two turtle species to assess the importance of conserving multiple wetlands and the upland matrix in which they occur. Spotted turtles ( Clemmys guttata) and Blanding's turtles ( Emydoidea blandingii) are considered threatened and endangered, respectively, in Maine where they are near the northeastern periphery of their geographic range. We used resightings of marked individuals (69 spotted, 16 Blanding's) and radiotelemetry (13 spotted, 9 Blanding's, radiotagged for one or two seasons) to investigate the movements and habitat use of both species. Individuals of both species used multiple wetlands throughout the year, including permanent and seasonal pools, forested swamps, and wet meadows. Pools occupied by spotted and Blanding's turtles were small (<0.4 ha), and they were less isolated from other wetlands than pools that did not contain turtles. Both species used uplands extensively for nesting, dormancy, and traveling between wetlands. Turtles traveled 70–570 m (spotted) and 100–1620 m ( Blanding's) to nest, and nests were located 1–120 m (spotted) and 70–410 m ( Blanding's) from the nearest wetland. Spotted and Blanding's turtles entered relatively dormant stages for 15–89 and 3–21 consecutive days, respectively, and upland dormancy sites were 12–80 m (spotted) and 30–110 m ( Blanding's) from the nearest wetland. Total distance traveled overland throughout a season was 0–1680 m and 0–6760 m for radiotagged spotted and Blanding's turtles, respectively. Most spotted turtles followed a seasonal pattern of habitat use: pools for spring activity, upland forest for relative dormancy during part of the summer, and wet meadows or forested swamps for overwintering. A seasonal pattern in the habitat use of Blanding's turtles was not as evident. Our study suggests that protecting small wetlands, maintaining generous terrestrial buffers around individual wetlands, and conserving wetlands in groups are important components of a landscape approach to species conservation. Resumen: Investigamos el uso de habitat y los movimientos de dos especies de tortugas para evaluar la importancia de conservar multiples humedales y la matriz terrestre en la que ocurren. Tortugas manchadas (Clemmys guttata) y tortugas de Blanding ( Emydoidea blandingii) estan consideradas como amenazadas y en peligro, respectivamente, en Maine donde se encuentran cerca de la periferia noreste de su rango geografico. Utilizamos reavistamientos de individuos marcados (69 manchadas, 16 de Blanding ) y radiotelemetria (13 manchadas, 9 de Blanding, radiomarcadas por 1-2 temporadas) para investigar los movimientos y uso de habitat de ambas especies. Los individuos de ambas especies utilizaron multiples humedales a lo largo del ano incluyendo charcas permanentes y temporales, cienagas boscosas y praderas inundadas. Las charcas ocupadas por tortugas manchadas y de Blanding fueron pequenas (<4 ha), y estaban menos aisladas de los demas humedales que no contenian tortugas. Ambas especies usaron terrenos elevados extensivamente para anidar, para los periodos de aletargamiento, para moverse entre humedales. Las tortugas viajaron entre 50 y 570 m (manchadas) y entre 100 y 1620 m (de Blanding ) para anidar, y los nidos se localizaron entre 1 y 120 m (manchadas) y entre 70 y 410 m (de Blanding ) del humedal mas cercano. Las tortugas manchadas y de Blanding entraron en etapas relativo de letargo por 15-89 y 3-21 dias consecutivos, respectivamente, y los sitios de letargo estaban entre 12 y 80 m (manchadas) y 30 y 110 m (de Blanding ) del humedal mas cercano. La distancia total recorrida en tierra en una temporada vario entre 0 y 1680 m y entre 0 y 6760 m para las tortugas manchadas y de Blanding radiomarcadas respectivamente. La mayoria de las tortugas manchadas tuvieron un patron estacional de uso del habitat: charcas para la actividad de primavera, bosque elevado cuando la etapa en letargo la etapa de lefargo relativo durante parte del verano y praderas inundadas o cienagas boscosas durante el invierno. En los movimientos de la tortuga de Blanding no fue evidente un patron estacional de uso de habitat. Nuestro estudio sugiere que la proteccion de humedales pequenos, la presencia de amortiguadores terrestres alrededor de los humedales y la conservacion de humedales en grupos son componentes importantes de una aproximacion de paisaje a la conservacion de especies.

Abstract: Residential development is occurring at unprecedented rates in the Rocky Mountain region of the United States, with unknown ecological consequences. We conducted our research in exurban development in Pitkin County, Colorado, between May and June in 1998 and 1999. Unlike suburban development, exur- ban development occurs beyond incorporated city limits, and the surrounding matrix remains the original ecosystem type. We surveyed songbirds and medium-sized mammals at 30, 180, and 330 m away from 40 homes into undeveloped land to examine the effect of houses along a distance gradient, and in developments of two different housing densities as well as undeveloped sites to examine the effect of housing density. We placed bird species into one of two groups for the house-distance effect: (1) human-adapted species, birds that occurred in higher densities close to developments and lower densities farther away and (2) human-sensitive species, birds that occurred in highest densities farthest from homes and in lowest densities close to develop- ment. For both groups, densities of individual species were statistically different between the 30- and 180-m sites. Six species were classified as human-adapted, and six were classified as human-sensitive for the house- distance effect. Dogs ( Canis familiaris ) and house cats ( Felis domesticus ) were detected more frequently closer to homes than farther away, and red foxes ( Vulpes vulpes ) and coyotes ( Canis latrans ) were detected more fre- quently farther away from houses. With respect to the effect of housing density, most avian densities did not differ significantly between high- and low-density development but were statistically different from undevel- oped sites. Six species were present in higher densities in developed areas, and eight species were present in higher densities in undeveloped parcels. Similar results were found for mammalian species, with dogs and cats detected more frequently in high-density developments and red foxes and coyotes detected more fre- quently in undeveloped parcels of land. From an ecological standpoint, it is preferable to cluster houses and leave the undeveloped areas in open space, as opposed to dispersing houses across the entire landscape.

Abstract: Logging is considered the most important threat to species in boreal forests. In contrast to eastern Canada, where most boreal forests remain largely untouched, in Fennoscandia it is possible to assess the cumulative, long-term effects of intensive forestry on wildlife. But harvesting of stands is rapidly changing Canadian boreal forests, which represent an important proportion of the world's boreal forests. We show that Fennoscandia and eastern Canada present striking similarities in terms of forest-age structure, natural-disturbance regime, and structure of bird assemblages, and we provide an assessment of the long-term effects of forestry on eastern Canadian birds of the boreal forest. We used life-history traits from habitat, nesting site, and geographical range to calculate an index of sensitivity to changes induced by modern forestry for boreal species of each region. Tropical migrants commonly found in eastern Canadian boreal forests have life-history traits that are not threat factors in relation to changes caused by modern forestry. Therefore, the general belief that tropical migrants in North America are more sensitive to landscape changes than those in Europe may not hold for species found in the boreal coniferous forests of eastern Canada. Nine Fennoscandian species present high levels of sensitivity, and at least eight eastern Canadian species are of similar concern. In both regions, most of the sensitive species are resident cavity nesters. Given the important similarities between the two regions, the northern expansion of commercial forestry in eastern Canada is likely to result in the significant decline of several resident species, as has occurred in Fennoscandia. Resumen: La tala es considerada la amenaza mas importante para las especies de los bosques boreales. En contraste con el este de Canada donde los bosques boreales permanecen practicamente sin tocar, es posible evaluar los efectos acumulativos de largo plazo de la actividad forestal intensiva sobre la vida silvestre en Fennoscandia. Sin embargo, la explotacion de madera esta cambiando rapidamente los bosques boreales canadienses, que representan una proporcion importante de los bosques boreales del mundo. Mostramos que Fennoscandia y el este de Canada tienen similitudes notables en terminos de la estructura de edades del bosque, el regimen de perturbaciones y la estructura de las comunidades de aves, y aportamos una evaluacion de los efectos a largo plazo de las actividades forestales sobre aves de los bosques boreales del este de Canada. Utilizamos rasgos de la historia de vida como habitat, sitio de anidacion y rango geografico para calcular un indice de sensibilidad a cambios inducidos por actividades forestales modernas en especies boreales de cada region. Los migrantes tropicales que son comunes en los bosques boreales del este de Canada tienen rasgos de historia de vida que no son factores de amenaza en relacion con cambios causados por la actividad forestal moderna. Por lo tanto, la creencia generalizada de una mayor sensibilidad de los migrantes tropicales a cambios en el paisaje en Norte America en comparacion con Europa puede no ser valida para las especies de los bosques boreales de coniferas del este de Canada. Nueve especies de Fennoscandia presentan altos niveles de sensibilidad, mientras que por lo menos ochos especies del este de Canada son de interes similar. En ambas regiones, la mayoria de las especies sensitivas son residentes y anidan en cavidades. Dadas las importantes similitudes entre las dos regiones, es probable que, como en Fennoscandia, la expansion de las actividades forestales comerciales en el este de Canada resulte en la declinacion significativa de varias especies residentes.

Abstract: The practice of supporting weak wild populations by capturing a fraction of the wild individuals, bringing them into captivity for reproduction, and releasing their offspring into the natural habitat to mix with wild ones is called supportive breeding and has been widely applied in the fields of conservation biology and fish and wildlife management. This procedure is intended to increase population size without introducing exogenous genes into the managed population. Previous work examining the genetic effects of a single generation of supportive breeding has shown that although a successful program increases the census population size, it may reduce the genetically effective population size and thereby induce excessive inbreeding and loss of genetic variation. We expand and generalize previous analyses of supportive breeding and consider the effects of multiple generations of supportive breeding on rates of inbreeding and genetic drift. We derived recurrence equations for the inbreeding coefficient and coancestry, and thereby equations for inbreeding and variance effective sizes, under three models for selecting captive breeders: at random, preferentially among those born in captivity, and preferentially among those born in the wild. Numerical examples indicate that supportive breeding, when carried out successfully over multiple generations, may increase not only the census but also the effective size of the supported population as a whole. If supportive breeding does not result in a substantial and continuous increase of the census size of the breeding population, however, it might be genetically harmful because of elevated rates of inbreeding and genetic drift.

Abstract: Various factors influence animal movements in fragmented landscapes, and determining these factors is key to understanding ecological processes at a landscape scale. My goals were (1) to determine what factors influence movements of Keel-billed Toucans ( Ramphastos sulfuratus ) in a fragmented landscape in southern Mexico and (2) to use this information to predict how movement patterns might change if the landscape was altered. I developed a cost-distance geographic information system model that adjusts Euclidean distances by a cost of moving through a certain habitat type. Cost was based on habitat preferences exhibited by toucans. I then used this model to predict how movements might be affected by removal of isolated trees and living fences from the pasture matrix and by removal of forest remnants. Toucans moved more frequently between remnants separated by a low cost-distance value. There was a cost-distance threshold beyond which movements between remnants were rare. Below this threshold, fruit abundance influenced toucan movements but remnant area was not influential in that toucans did not preferentially move to large patches. Remnants close to various other remnants were more frequently visited by toucans, indicating that landscape connectivity influences toucan movements. Toucans incurred a 10–30% cost increase when moving in computer-simulated landscapes, indicating that changes in forest cover or configuration of habitats may negatively affect toucan populations, assuming that increased cost has a fitness consequence. Cost-distance modeling has been relatively unexplored and may be a valuable tool for determining how the configuration of a landscape impedes or facilitates animal movements. Resumen: Diversos factores influyen sobre los movimientos de animales en paisajes fragmentados, y la determinacion de esos factores es clave para entender los procesos ecologicos a nivel de paisaje. Mis metas fueron (1) determinar los factores que influyen sobre los movimientos de tucanes ( Ramphastos sulfurarus ) en un paisaje fragmentado en el sur de Mexico y (2) utilizar esta informacion para predecir cambios en los patrones de movimiento si se altera el paisaje. Desarrolle un modelo de sistema de informacion geografica de costo-distancia que ajusta las distancia Euclidianas por el costo de moverse a traves de un cierto tipo de habitat. El costo se baso en las preferencias de habitat que mostraron los tucanes. Luego utilice esto modelo para predecir como se afectarian los movimientos por la remocion de arboles aislados y cercos vivos de la matriz de pastura y por la remocion de remanentes de bosque. Los tucanes se movieron con mayor frecuencia entre remanentes separados por un bajo valor de costo-distancia. Hubo un umbral de costo-distancia mas alla del cual los movimientos entre remanentes fueron raros. Por debajo del umbral, la abundancia de frutos influyo los movimientos pero la superficie del remanente no influyo escuanto los tucanes no prefirieron moverse a parches grandes. Los remanentes cerca de otros remanentes fueron visitados por tucanes mas frecuentemente, lo que indica que la conectividad influye sobre los movimientos de tucanes. Los tucanes incurrieron en un incremento del 10–30% del costo cuando se desplazalan en paisajes simulados en computadora, lo que indica que cambios en la cubierta forestal o en la configuracion de habitats pueden afectar negativamente a las poblaciones de tucanes, suponiendo que el incremento de costo tiene consecuencias en la adaptabilidad. El modelaje de costo-distancia ha sido relativamente poco explorado y los puede ser una valiosa herramienta para determinar como la configuracion de un paisaje impide o facilita movimientos de animales.

Abstract: It has been 30 years since environmental concern was first expressed over the prospect of large- scale resource development in the Arctic. Human effects are more extensive within the tundra biome now than at any time in the past. With or without predicted climatic changes, interaction among different natural and contemporary anthropogenic disturbance regimes are bound to have a significant effect on local and re- gional vegetation patterns and plant migration. We summarize the results of recent studies of patchy anthro- pogenic disturbance. We pay particular attention to the natural regeneration of plant communities, empha- size patch dynamics over the medium term (20- 75 years), and discuss the data in the context of popular models of vegetation change following disturbance. Disturbance is important because it produces patches of partially or totally denuded ground that permit propagule establishment but may also open affected areas to erosion. Even relatively low-intensity, small-scale disturbances have immediate and persistent effects on arc- tic vegetation and soils. On all but the wettest sites, the patches support new, relatively stable vegetation states. Where slope is minimal, such disturbances are capable of expanding over large areas in as short a time as 4 years. The effects result in an artificial mosaic of patches of highly variable quality and quantity that comprise feeding and nesting habitats for terrestrial herbivores.

Abstract: This study examines the effects of the short-lived insecticide carbaryl, a neurotoxin, on amphibian communities experiencing natural stresses of competition and predation. Tadpoles of three species ( Woodhouse's toad [Bufo woodhousii], gray treefrog [Hyla versicolor], and green frog [Rana clamitans]), representing a commonly encountered assemblage in Missouri, were reared in outdoor polyethylene pond mesocosms. We determined the effects of initial tadpole density ( low or high), predation (newts [ Notophthalmus viridescens] absent or present), chemical exposure (0, 3.5, or 7.0 mg /L carbaryl), and their interactions on body mass, larval period, and survival to metamorphosis. Green frogs in high-density ponds did not reach metamorphosis, but metamorphs in low-density ponds and tadpoles in high-density ponds were not significantly affected by treatments or their interaction. Carbaryl reduced survival to metamorphosis in toads and treefrogs and increased mass at metamorphosis in treefrogs. Effects of carbaryl varied with predator environment and initial larval density. Interactions of carbaryl with predator and with density may result in an indirect effect of carbaryl causing increased food resources through the elimination of zooplankton populations that may compete for similar resources. Our results indicate that differences in biotic conditions influenced the potency of carbaryl and that even low concentrations induce changes that may alter community dynamics in ways not predicted from single-factor, laboratory-based studies. Resumen: Este estudio examina los efectos de un insecticida de vida corta (carbaryl, un neurotoxico) en comunidades de anfibios que se encuentran experimentando estreses naturales de competencia y depredacion. Los renacuajos de tres especies (el sapo casa de madera [Bufo woodhousii], la rana arboricola gris [Hyla versicolor] y la rana verde [Rana clamitans]), representantes de un ensamblaje comun en Missouri, fueron mantenidas en mesocosmos de estanques de polietileno. Se determinaron los efectos de la densidad inicial de los renacuajos ( baja o alta), la depredacion (tritones [Notophthalmus viridescens] ausentes o presentes), la exposicion quimica (0, 3.5 o 7.0 mg /L de carbaryl) y sus interacciones sobre la masa corporal, el periodo larval, y la supervivencia a la metamorfosis. Las ranas verdes en estanques con altas densidades no alcanzaron la metamorfosis, pero los metamorfos en los estanques con baja densidad y los renacuajos en estanques con alta densidad no fueron afectados significativamente por los tratamientos ni por sus interacciones. El carbaryl redujo la supervivencia a la metamorfosis e incremento la masa corporal durante la metamorfosis de las ranas arboricolas. Los efectos del carbaryl variaron dependiendo del ambiente de depredacion y de la densidad larval inicial. Las interacciones de carbaryl con el depredador y con la densidad pueden resultar en un efecto indirecto del carbaryl al ocasionar un incremento en los recursos alimenticios mediante la eliminacion de poblaciones de zooplancton que podrian competir por recursos similares. Nuestros resultados indican que las diferencias en las condiciones bioticas influyen en la potencia del carbaryl y hasta podrian alterar las dinamicas comunitarias de formas no predecibles a partir de estudios de laboratorio basados en un solo factor.

Abstract: Limitation of predator populations by prey availability and the effects of predators on prey populations are widely recognized as important ecological processes that affect carnivore conservation. Interspecific competition can also be a strong limiting factor for carnivore populations, and the effects of competition help explain why some carnivore species are prone to extinction. Competition among carnivores is unusual in some ways, so some predictions from traditional models of competition do not hold. For example, an increase in the density of prey can increase the effect of competition among carnivores, rather than weakening it. I used published data from African wild dogs ( Lycaon pictus) to highlight four complexities that can modify the effects of competition on the population dynamics of carnivores: habitat fragmentation, counterintuitive effects of prey density, predator-prey size ratios, and habitat type. Resumen: La restriccion sobre poblaciones de depredadores ocasionada por la disponibilidad de presas y los efectos de depredadores en poblaciones de presas son ampliamente reconocidos como procesos ecologicos importantes que afectan la conservacion de carnivoros. A pesar de ello, la competencia interespecifica tambien puede ser un fuerte factor limitante para las poblaciones de carnivoros y los efectos de la competencia ayudan a explicar el porque algunas especies carnivoras son propensas a extinguirse. La competencia entre carnivoros es poco comun de cierta forma, asi que algunas predicciones de modelos tradicionales de competencia no se cumplen. Por ejemplo, un incremento en la densidad de presas puede incrementar el efecto de la competencia entre carnivoros, en lugar de disminuirlo. Utilice datos de trabajos publicados de perros silvestres africanos ( Lycaon pictus) para resaltar cuatro complicaciones que pueden modificar los efectos de la competencia en la dinamica poblacional de carnivoros: fragmentacion del habitat, efectos contraintuitivos de la densidad de presas, tamano de las proporciones depredador/presa y tipo de habitat.

Abstract: Since the 1980s, initiatives to encourage rural people tobecome an integral part of conservation efforts have at-tracted wide support (McNeely 1992; Ghimire 1994).Strategies for achieving this participation in Africa haveoften focused on the economic link between local com-munities and protected areas. The role of cultural valuesin building support for conservation has been noted (Mc-Neely & Miller 1984; Brownrigg 1985) but has beenlargely ignored in practice. Interest has remained rhetor-ical, and few initiatives exist that actively seek to inte-grate values relevant to local communities into conserva-tion programs and the management of Africa’s protectedareas. This is perhaps surprising, because in the Westthe relationship between culture, history, conservation,and protected areas has been the subject of considerableresearch and scholarship (Nash 1982; Adams 1996; Neu-mann 1998).The emphasis on economic incentives for conserva-tion stems, in part, from the linking of conservation anddevelopment (World Conservation Union et al. 1980;World Commission on Environment and Development1987; World Conservation Union 1991). Although pov-erty and environmental degradation often are closely re-lated, most of Africa’s protected areas do not and almostcertainly will not contribute significantly to reducing pov-erty. Conservation initiatives must recognize economicrealities. But the current focus on economic incentivesfor involving communities in conservation efforts re-sults, to a considerable extent, from the theory that mar-ket forces will conserve and protect the environment,lessening the need for government intervention. This as-sertion, a product of “neoliberal” economics, has stronglyinfluenced political and popular thinking in recent de-cades and has profoundly affected international develop-ment aid practices, including many internationally fundedconservation programs in developing countries (Struh-saker 1998). In poor countries, economic approachescan appear especially attractive, and their presentationas humanitarian in intention (Holdgate & Munro 1995)has guaranteed them almost universal acceptance.The intention to make wildlife and protected areas“pay for themselves” has stimulated a range of “commu-nity conservation” initiatives aimed at building a localconstituency for conservation. These include protected-area outreach programs with an emphasis on sharingrevenues, resources, and opportunities with local com-munities; collaborative management in which govern-ments and communities join to manage protected areasfor sustainable production; and community-based wild-life management aimed at economic development ratherthan conservation (Hulme & Murphree 1999). Integratedconservation and development projects also attempt toreduce pressures on protected areas by supporting lo-cal economic development. Calculation of the monetaryworth of wildlife, nature, and landscape through contin-gent valuation methods also contributes to the commer-cialization of conservation and the downplaying of cul-tural values.Despite the range of initiatives and investment of do-nor funds, it has proved difficult to provide tangible ben-efits from conservation to local communities in Africa.Although the political and economic regimes of manydeveloping countries aggravate the difficulties of chan-neling benefits to communities, most protected areas donot realize sufficient revenue to offset the costs to com-munities of retaining them (Mason 1995; Norton-Grif-fiths & Southey 1995; Emerton 1998). Hundreds of Af-rica’s conservation areas are unknown, inaccessible, andlacking in charismatic species or dramatic landscapes toattract tourists. Even where these exist in abundance(e.g., Uganda’s Mgahinga Gorilla National Park), tourismrevenues are not sufficient to meet community demandsand management costs and to subsidize operations inother equally important, although less attractive, conser-vation areas (Infield & Adams 1999). Although nature