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1.
Conserv Biol ; 37(6): e14139, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37394972

RESUMO

Despite being central to the implementation of conservation policies, the usefulness of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species is hampered by the 14% of species classified as data-deficient (DD) because information to evaluate these species' extinction risk was lacking when they were last assessed or because assessors did not appropriately account for uncertainty. Robust methods are needed to identify which DD species are more likely to be reclassified in one of the data-sufficient IUCN Red List categories. We devised a reproducible method to help red-list assessors prioritize reassessment of DD species and tested it with 6887 DD species of mammals, reptiles, amphibians, fishes, and Odonata (dragonflies and damselflies). For each DD species in these groups, we calculated its probability of being classified in a data-sufficient category if reassessed today from covariates measuring available knowledge (e.g., number of occurrence records or published articles available), knowledge proxies (e.g., remoteness of the range), and species characteristics (e.g., nocturnality); calculated change in such probability since last assessment from the increase in available knowledge (e.g., new occurrence records); and determined whether the species might qualify as threatened based on recent rate of habitat loss determined from global land-cover maps. We identified 1907 species with a probability of being reassessed in a data-sufficient category of >0.5; 624 species for which this probability increased by >0.25 since last assessment; and 77 species that could be reassessed as near threatened or threatened based on habitat loss. Combining these 3 elements, our results provided a list of species likely to be data-sufficient such that the comprehensiveness and representativeness of the IUCN Red List can be improved.


Priorización de la reevaluación de las especies con datos deficientes en la Lista Roja de la UICN Resumen No obstante que es fundamental para la implementación de políticas de conservación, la utilidad de la Lista Roja de Especies Amenazadas de la Unión Internacional para la Conservación de la Naturaleza (UICN) está limitada por el 14% de especies clasificadas con datos deficientes (DD) debido a que la información para evaluar el riesgo de extinción de estas especies no existía cuando fueron evaluadas la última vez o porque los evaluadores no consideraron la incertidumbre apropiadamente. Se requieren métodos robustos para identificar las especies DD con mayor probabilidad de ser reclasificadas en alguna de las categorías en la Lista Roja UICN con datos suficientes. Diseñamos un método reproducible para ayudar a que los evaluadores de la lista roja prioricen la reevaluación de especies DD y lo probamos con 6,887 especies DD de mamíferos, reptiles, anfibios, peces y Odonata (libélulas y caballitos del diablo). Para cada una de las especies DD en estos grupos, calculamos la probabilidad de ser clasificadas en una categoría con datos suficientes si fuera reevaluada hoy a partir de covariables que miden el conocimiento disponible (e.g., número de registros de ocurrencia o artículos publicados disponibles), sustitutos de conocimiento (e.g., extensión del rango de distribución) y características de la especie ((e.g., nocturnidad); calculamos el cambio en tal probabilidad desde la última reevaluación a partir del incremento en el conocimiento disponible (e.g., registros de ocurrencia nuevos); y determinamos si las especies podrían calificar como amenazadas con base en pérdidas de hábitat recientes a partir de mapas globales de cobertura de suelo recientes. Identificamos 1,907 especies con una probabilidad >0.5 de ser reclasificados en una categoría con datos suficientes; 624 especies cuya probabilidad aumentó en >0.25 desde la última evaluación, y 77 especies que podrían ser reclasificadas como casi en peligro con base en la pérdida de hábitat. Combinando estos 3 elementos, nuestros resultados proporcionaron una lista de especies probablemente con datos suficientes de tal modo que la exhaustividad y la representatividad de la Lista Roja de la UICN pueden ser mejoradas.


Assuntos
Conservação dos Recursos Naturais , Odonatos , Animais , Espécies em Perigo de Extinção , Extinção Biológica , Ecossistema , Mamíferos , Peixes , Biodiversidade
2.
Nature ; 605(7909): 285-290, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35477765

RESUMO

Comprehensive assessments of species' extinction risks have documented the extinction crisis1 and underpinned strategies for reducing those risks2. Global assessments reveal that, among tetrapods, 40.7% of amphibians, 25.4% of mammals and 13.6% of birds are threatened with extinction3. Because global assessments have been lacking, reptiles have been omitted from conservation-prioritization analyses that encompass other tetrapods4-7. Reptiles are unusually diverse in arid regions, suggesting that they may have different conservation needs6. Here we provide a comprehensive extinction-risk assessment of reptiles and show that at least 1,829 out of 10,196 species (21.1%) are threatened-confirming a previous extrapolation8 and representing 15.6 billion years of phylogenetic diversity. Reptiles are threatened by the same major factors that threaten other tetrapods-agriculture, logging, urban development and invasive species-although the threat posed by climate change remains uncertain. Reptiles inhabiting forests, where these threats are strongest, are more threatened than those in arid habitats, contrary to our prediction. Birds, mammals and amphibians are unexpectedly good surrogates for the conservation of reptiles, although threatened reptiles with the smallest ranges tend to be isolated from other threatened tetrapods. Although some reptiles-including most species of crocodiles and turtles-require urgent, targeted action to prevent extinctions, efforts to protect other tetrapods, such as habitat preservation and control of trade and invasive species, will probably also benefit many reptiles.


Assuntos
Conservação dos Recursos Naturais , Extinção Biológica , Répteis , Jacarés e Crocodilos , Anfíbios , Animais , Biodiversidade , Aves , Mamíferos , Filogenia , Répteis/classificação , Medição de Risco , Tartarugas
3.
Ecol Appl ; 32(3): e2534, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35044023

RESUMO

Continental- and regional-scale assessments of gaps in protected area networks typically use relatively coarse range maps for well documented species groups, creating uncertainty about the fate of unexamined biodiversity and providing insufficient guidance for land managers. By building habitat suitability models for a taxonomically diverse group of 2216 imperiled plants and animals, we revealed comprehensive and detailed protection opportunities in the conterminous United States. Summing protection-weighted range-size rarity (PWRSR, the product of the percent of modeled habitat outside of protected areas and the inverse of modeled habitat extent) uncovered novel patterns of biodiversity importance. Concentrations of unprotected imperiled species in places such as the northern Sierra Nevada, central and northern Arizona, the Rocky Mountains of Utah and Colorado, southeastern Texas, southwestern Arkansas, and Florida's Lake Wales Ridge have rarely if ever been featured in continental- and regional-scale analyses. Inclusion of diverse taxa (vertebrates, freshwater mussels, crayfishes, bumble bees, butterflies, skippers, and vascular plants) partially drove these new patterns. When analyses were restricted to groups typically included in previous studies (birds, mammals, and amphibians), up to 53% of imperiled species in other groups were left out. The finer resolution of modeled inputs (990 m) also resulted in a more geographically dispersed pattern. For example, 90% of the human population of the conterminous United States lives within 50 km of modeled habitat for one or more species with high PWRSR scores. Over one-half of the habitat for 818 species occurs within federally lands managed for biodiversity protection; an additional 360 species have over one-half of their modeled habitat on federal multiple use land. Freshwater animals occur in places with poorer landscape condition but with less exposure to climate change than other groups, suggesting that habitat restoration is an important conservation strategy for these species. The results provide fine-scale, taxonomically diverse inputs for local and regional priority-setting and show that although protection efforts are still widely needed on private lands, notable gains can be achieved by increasing protection status on selected federal lands.


Assuntos
Borboletas , Conservação dos Recursos Naturais , Animais , Biodiversidade , Aves , Ecossistema , Mamíferos
4.
Trends Ecol Evol ; 37(4): 359-370, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35065822

RESUMO

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species is central in biodiversity conservation, but insufficient resources hamper its long-term growth, updating, and consistency. Models or automated calculations can alleviate those challenges by providing standardised estimates required for assessments, or prioritising species for (re-)assessments. However, while numerous scientific papers have proposed such methods, few have been integrated into assessment practice, highlighting a critical research-implementation gap. We believe this gap can be bridged by fostering communication and collaboration between academic researchers and Red List practitioners, and by developing and maintaining user-friendly platforms to automate application of the methods. We propose that developing methods better encompassing Red List criteria, systems, and drivers is the next priority to support the Red List.


Assuntos
Conservação dos Recursos Naturais , Espécies em Perigo de Extinção , Animais , Biodiversidade , Comunicação , Extinção Biológica
5.
Data Brief ; 31: 105705, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32490077

RESUMO

The data presented in this article are related to the research article entitled "Progress on National Biodiversity Indicator Reporting and Prospects for Filling Indicator Gaps in Southeast Asia " (Han et al., 2020). We examined quantifiable information about biodiversity indicators from the most recent two national reports (i.e., 4th in 2010 and 5th in 2015) to the United Nation's Convention on Biological Diversity (CBD) by the 10-member countries of the Association of Southeast Asian Nations (ASEAN): Brunei Darussalam, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand and Vietnam. This article presents the number of indicators, their level of development, and detailed lists of indicators for each country, and demonstrates general improvement in indicator use by the highest level of government reporting about implementation of the CBD at the national scale.

6.
Nat Ecol Evol ; 3(1): 53-61, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30532042

RESUMO

Preserving the evolutionary history and ecological functions that different species embody, in addition to species themselves, is a growing concern for conservation. Recent studies warn that conservation priority regions identified using species diversity differ from those based on phylogenetic or functional diversity. However, spatial mismatches in conservation priority regions need not indicate low surrogacy among these dimensions in conservation planning. Here, we use data for 10,213 terrestrial vertebrate species across the Americas to evaluate surrogacy; that is, the proportion of phylogenetic or functional diversity represented in conservation plans targeting species. We find that most conservation plans targeting species diversity also represent phylogenetic and functional diversity well, despite spatial mismatches in the priority regions identified by each plan. However, not all phylogenetic and functional diversity is represented within species-based plans, with the highest-surrogacy conservation strategy depending on the proportion of land area included in plans. Our results indicate that targeting species diversity could be sufficient to preserve much of the phylogenetic and functional dimensions of biodiversity in terrestrial vertebrates of the Americas. Incorporating phylogenetic and functional data in broad-scale conservation planning may not always be necessary, especially when the cost of doing so is high.


Assuntos
Biodiversidade , Conservação dos Recursos Naturais , Vertebrados/genética , América , Animais , Filogenia
7.
Proc Biol Sci ; 285(1872)2018 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-29436494

RESUMO

Global variation in species richness is widely recognized, but the explanation for what drives it continues to be debated. Previous efforts have focused on a subset of potential drivers, including evolutionary rate, evolutionary time (maximum clade age of species restricted to a region), dispersal (migration from one region to another), ecological factors and climatic stability. However, no study has evaluated these competing hypotheses simultaneously at a broad spatial scale. Here, we examine their relative contribution in determining the richness of the most comprehensive dataset of tetrapods to our knowledge (84% of the described species), distinguishing between the direct influences of evolutionary rate, evolutionary time and dispersal, and the indirect influences of ecological factors and climatic stability through their effect on direct factors. We found that evolutionary time exerted a primary influence on species richness, with evolutionary rate being of secondary importance. By contrast, dispersal did not significantly affect richness patterns. Ecological and climatic stability factors influenced species richness indirectly by modifying evolutionary time (i.e. persistence time) and rate. Overall, our findings suggest that global heterogeneity in tetrapod richness is explained primarily by the length of time species have had to diversify.


Assuntos
Anfíbios , Biodiversidade , Evolução Biológica , Aves , Mamíferos , Répteis , Distribuição Animal , Migração Animal , Animais , Clima , Fatores de Tempo
8.
PLoS One ; 12(10): e0185683, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28982152

RESUMO

Increasing attention to pollinators and their role in providing ecosystem services has revealed a paucity of studies on long-term population trends of most insect pollinators in many parts of the world. Because targeted monitoring programs are resource intensive and unlikely to be performed on most insect pollinators, we took advantage of existing collection records to examine long-term trends in northeastern United States populations of 26 species of hawk moths (family Sphingidae) that are presumed to be pollinators. We compiled over 6,600 records from nine museum and 14 private collections that spanned a 112-year period, and used logistic generalized linear mixed models (GLMMs) to examine long-term population trends. We controlled for uneven sampling effort by adding a covariate for list length, the number of species recorded during each sampling event. We found that of the 22 species for which there was sufficient data to assess population trends, eight species declined and four species increased in detection probability (the probability of a species being recorded during each year while accounting for effort, climate, and spatial effects in the GLMMs). Of the four species with too few records to statistically assess, two have disappeared from parts of their ranges. None of the four species with diurnal adults showed a trend in detection probability. Two species that are pests of solanaceous crops declined, consistent with a seven-fold drop in the area planted in tobacco and tomato crops. We found some evidence linking susceptibility to parasitoidism by the introduced fly Compsilura concinnata (Tachinidae) to declines. Moths with larvae that feed on vines and trees, where available evidence indicates that the fly is most likely to attack, had a greater propensity to decline than species that use herbs and shrubs as larval host plants. Species that develop in the spring, before Compsilura populations have increased, did not decline. However, restricting the analysis to hawk moth records from areas outside of a "refuge" area where Compsilura does not occur did not significantly increase the intensity of the declines as would be predicted if Compsilura was the primary cause of declines. Forests have recovered over the study period across most of the northeastern U.S., but this does not appear to have been a major factor because host plants of several of the declining species have increased in abundance with forest expansion and maturation. Climate variables used in the GLMMs were not consistently related to moth detection probability. Hawk moth declines may have ecological effects on both the plants pollinated by these species and vertebrate predators of the moths.


Assuntos
Mariposas/fisiologia , Polinização , Animais , Clima , Documentação , New England , Densidade Demográfica
9.
Sci Data ; 3: 160007, 2016 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-26881749

RESUMO

Two processes for regional environmental assessment are currently underway: the Global Environment Outlook (GEO) and Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES). Both face constraints of data, time, capacity, and resources. To support these assessments, we disaggregate three global knowledge products according to their regions and subregions. These products are: The IUCN Red List of Threatened Species, Key Biodiversity Areas (specifically Important Bird &Biodiversity Areas [IBAs], and Alliance for Zero Extinction [AZE] sites), and Protected Planet. We present fourteen Data citations: numbers of species occurring and percentages threatened; numbers of endemics and percentages threatened; downscaled Red List Indices for mammals, birds, and amphibians; numbers, mean sizes, and percentage coverages of IBAs and AZE sites; percentage coverage of land and sea by protected areas; and trends in percentages of IBAs and AZE sites wholly covered by protected areas. These data will inform the regional/subregional assessment chapters on the status of biodiversity, drivers of its decline, and institutional responses, and greatly facilitate comparability and consistency between the different regional/subregional assessments.


Assuntos
Biodiversidade , Conservação dos Recursos Naturais , Anfíbios , Animais , Aves , Ecossistema , Espécies em Perigo de Extinção , Mamíferos
10.
PLoS One ; 9(11): e112046, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25409183

RESUMO

Recognizing the imperiled status of biodiversity and its benefit to human well-being, the world's governments committed in 2010 to take effective and urgent action to halt biodiversity loss through the Convention on Biological Diversity's "Aichi Targets". These targets, and many conservation programs, require monitoring to assess progress toward specific goals. However, comprehensive and easily understood information on biodiversity trends at appropriate spatial scales is often not available to the policy makers, managers, and scientists who require it. We surveyed conservation stakeholders in three geographically diverse regions of critical biodiversity concern (the Tropical Andes, the African Great Lakes, and the Greater Mekong) and found high demand for biodiversity indicator information but uneven availability. To begin to address this need, we present a biodiversity "dashboard"--a visualization of biodiversity indicators designed to enable tracking of biodiversity and conservation performance data in a clear, user-friendly format. This builds on previous, more conceptual, indicator work to create an operationalized online interface communicating multiple indicators at multiple spatial scales. We structured this dashboard around the Pressure-State-Response-Benefit framework, selecting four indicators to measure pressure on biodiversity (deforestation rate), state of species (Red List Index), conservation response (protection of key biodiversity areas), and benefits to human populations (freshwater provision). Disaggregating global data, we present dashboard maps and graphics for the three regions surveyed and their component countries. These visualizations provide charts showing regional and national trends and lay the foundation for a web-enabled, interactive biodiversity indicators dashboard. This new tool can help track progress toward the Aichi Targets, support national monitoring and reporting, and inform outcome-based policy-making for the protection of natural resources.


Assuntos
Biodiversidade , Monitorização de Parâmetros Ecológicos/métodos , Sistemas de Gerenciamento de Base de Dados , Cooperação Internacional , Dinâmica Populacional
11.
BMC Ecol ; 12: 1, 2012 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-22284854

RESUMO

BACKGROUND: The Andes-Amazon basin of Peru and Bolivia is one of the most data-poor, biologically rich, and rapidly changing areas of the world. Conservation scientists agree that this area hosts extremely high endemism, perhaps the highest in the world, yet we know little about the geographic distributions of these species and ecosystems within country boundaries. To address this need, we have developed conservation data on endemic biodiversity (~800 species of birds, mammals, amphibians, and plants) and terrestrial ecological systems (~90; groups of vegetation communities resulting from the action of ecological processes, substrates, and/or environmental gradients) with which we conduct a fine scale conservation prioritization across the Amazon watershed of Peru and Bolivia. We modelled the geographic distributions of 435 endemic plants and all 347 endemic vertebrate species, from existing museum and herbaria specimens at a regional conservation practitioner's scale (1:250,000-1:1,000,000), based on the best available tools and geographic data. We mapped ecological systems, endemic species concentrations, and irreplaceable areas with respect to national level protected areas. RESULTS: We found that sizes of endemic species distributions ranged widely (< 20 km2 to > 200,000 km2) across the study area. Bird and mammal endemic species richness was greatest within a narrow 2500-3000 m elevation band along the length of the Andes Mountains. Endemic amphibian richness was highest at 1000-1500 m elevation and concentrated in the southern half of the study area. Geographical distribution of plant endemism was highly taxon-dependent. Irreplaceable areas, defined as locations with the highest number of species with narrow ranges, overlapped slightly with areas of high endemism, yet generally exhibited unique patterns across the study area by species group. We found that many endemic species and ecological systems are lacking national-level protection; a third of endemic species have distributions completely outside of national protected areas. Protected areas cover only 20% of areas of high endemism and 20% of irreplaceable areas. Almost 40% of the 91 ecological systems are in serious need of protection (= < 2% of their ranges protected). CONCLUSIONS: We identify for the first time, areas of high endemic species concentrations and high irreplaceability that have only been roughly indicated in the past at the continental scale. We conclude that new complementary protected areas are needed to safeguard these endemics and ecosystems. An expansion in protected areas will be challenged by geographically isolated micro-endemics, varied endemic patterns among taxa, increasing deforestation, resource extraction, and changes in climate. Relying on pre-existing collections, publically accessible datasets and tools, this working framework is exportable to other regions plagued by incomplete conservation data.


Assuntos
Biodiversidade , Conservação dos Recursos Naturais/métodos , Demografia , Ecossistema , Modelos Teóricos , Animais , Bolívia , Geografia , Mapas como Assunto , Peru , Especificidade da Espécie
12.
Conserv Biol ; 20(1): 111-21, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16909664

RESUMO

Since 1960, most of the forest surrounding the La Selva Biological Station, an intensively studied tropical research facility in Costa Rica, has been converted to agricultural uses. We used quantitative censuses and analysis of previously published categorical abundances to assess changes in the bird community, and we evaluated potential causes of species-specific changes by assessing their association with habitat, diet, participation in mixed-species flocks, and nest type. Approximately the same percentage of species increased as decreased in abundance from 1960 to 1999 (10-20% of all species, depending on method of assessment). Diet was the single most important trait associated with declining species. At least 50% of the species that declined have insectivorous diets. Use of forest habitat and participation in mixed-species flocks were also significant factors associated with declines, but nest type was unrelated to change in abundance. The species that increased in abundance tended to occur in open habitats and have omnivorous diets. These results reinforce the importance of several population risk factors associated with tropical understory insectivory and mixed-species flocking: patchy spatial distribution, low population density, large home range, and dietary specialization. La Selva's protected area (1611 ha), despite a forested connection on one boundary with a higher elevation national park, is apparently too small to maintain at least one major guild (understory insectivores). This first quantitative assessment of bird community change at La Selva highlights the need to intensify study of the mechanisms and consequences of biological diversity change in tropical forest fragments.


Assuntos
Aves/crescimento & desenvolvimento , Conservação dos Recursos Naturais , Dieta , Cadeia Alimentar , Insetos/crescimento & desenvolvimento , Árvores , Agricultura , Animais , Biodiversidade , Costa Rica , Ecossistema , Dinâmica Populacional , Especificidade da Espécie , Clima Tropical
13.
Nature ; 439(7073): 161-7, 2006 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-16407945

RESUMO

As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog (Atelopus sp.) vanished along with the golden toad (Bufo periglenes). An estimated 67% of the 110 or so species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with 'very high confidence' (> 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable.


Assuntos
Anfíbios/microbiologia , Anfíbios/fisiologia , Biodiversidade , Efeito Estufa , Altitude , Animais , Bufonidae/microbiologia , Bufonidae/fisiologia , Costa Rica , Umidade , Modelos Biológicos , Dinâmica Populacional , Risco , Temperatura , Árvores/fisiologia
14.
Science ; 306(5702): 1783-6, 2004 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-15486254

RESUMO

The first global assessment of amphibians provides new context for the well-publicized phenomenon of amphibian declines. Amphibians are more threatened and are declining more rapidly than either birds or mammals. Although many declines are due to habitat loss and overutilization, other, unidentified processes threaten 48% of rapidly declining species and are driving species most quickly to extinction. Declines are nonrandom in terms of species' ecological preferences, geographic ranges, and taxonomic associations and are most prevalent among Neotropical montane, stream-associated species. The lack of conservation remedies for these poorly understood declines means that hundreds of amphibian species now face extinction.


Assuntos
Anfíbios , Biodiversidade , Ecossistema , Anfíbios/classificação , Animais , Conservação dos Recursos Naturais , Meio Ambiente , Dinâmica Populacional
15.
Oecologia ; 93(2): 256-262, 1993 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28313615

RESUMO

I studied the life cycle of a botfly (Diptera: Muscidae: Philornis carinatus) and examined the effects of botfly ectoparasitism on nestling house wrens (Passeriformes: Troglodytidae: Troglodytes aedon) during three years in Costa Rica. At three study sites, I found that nestlings were relatively unaffected by botflies, in contrast to all other studies of birds infected with philornid botflies. At Monteverde, the main study site, infected chicks grew slightly slower and had slightly shorter tarsi and wing chords than uninfected chicks, but both groups fledged at similar weights. Since weight at fledging is the only growth character associated with post-fledging survivorship, botfly infections likely cost wrens little in terms of fitness. At all sites, fledging success did not differ between infected and uninfected nests. Botfly infections were more prevalent at two lower elevation sites than at the high elevation Monteverde side. Infection prevalence increased during the nesting season at all study sites, which suggests a botfly life cycle in which adult population levels increase during the wren breeding season and then decline during a dormant period when wrens are not nesting. Finally, botflies may attack chicks throughout the period before fledging, but there is no indication they locate nests before hatching. In sum, botfly parasitism on wrens appears to be benign, perhaps because the study sites are at the edge of the botfly's range or because wrens are not a preferred host.

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