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Consistency in supplemental food availability affects the space use of wintering birds
No full text47 pagesAcross the globe, millions of people feed wild birds and this practice has profound implications for many bird species. To better understand the effects of this supplemental feeding, many researchers have compared birds with access to inexhaustible supplemental food to those without access. However, the consistency of supplemental food availability varies with people’s provisioning habits because some people fill their feeders daily while others do so sporadically. As the consistency of food changes, a bird’s foraging strategy, including its use of space, should change. To determine how space use varies with the consistency of supplemental food, we surveyed three species with access to experimental feeders that provided constant, pulsed, or no access to food. We conducted these surveys at two locations—near and far from the feeder—within nine sites to determine differences in space use among and within sites. Access to supplemental food, regardless of feeding regime, anchored the movements of each species near the feeders. However, the different feeding regimes had different effects on space use. Birds with constant access were continually anchored near the feeders while the birds with pulsed access were temporarily anchored near the feeders. We found that for only one of the three species, black-capped chickadee, that there were two more birds near feeders with pulsed access when food was available compared to near feeders with constant access. Supplemental feeders act as spatial anchors but do so in different ways across species and feeding regimes with potentially different implications for survival and population dynamics
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
HABITAT LOSS, FRAGMENTATION AND CLIMATIC DRIVERS OF AVIAN DIVERSITY ACROSS THE ANDES AND IMPLICATIONS FOR CLIMATE CHANGE
No full text218 pagesThe diversity of life on our planet is under siege. Around the world habitat loss, degradation, and fragmentation are among the main threats to biodiversity, with negative outcomes exacerbated by climate change. Our poor understanding of the mechanisms governing ecological responses to global change, especially in tropical montane systems, constrains our ability to predict and mitigate these threats to biodiversity. This dissertation addresses the effects of habitat loss, fragmentation and climatic drivers on avian diversity across the Andes, with a special focus on the implications for climate change. Specifically, we examined (1) sensitivity of birds to forest cover and patch size within one of the most threatened ecosystems of the Andes, Polylepis forests, (2) how factors related to climate, landscape configuration and human activities at regional scales shape patterns of avian species richness and endemism along elevational gradients in the western slope of the Andes, (3) the extent to which relationships between elevation and avian diversity at continental scales are influenced by complex interactions between temperature and precipitation, and (4) the degree to which avian communities in the Andes can persist under future climate scenarios. We surveyed 88 bird species across 59 Polylepis patches within five glacier valleys (3,300 to 4,700 m a.s.l.) of Cordillera Blanca (Ancash-Peru). We also compiled elevational ranges of 212 species within the region and 2,384 across the continent, together with climatic and environmental covariables across 16 elevational gradients across the Andes of Colombia, Ecuador, Peru, Bolivia, Argentina and Chile. At landscape scales, avian communities at high elevations seemed adapted to naturally patchy Polylepis landscapes. Species richness was greatest within small fragments and areas with reduced forest cover. Polylepis specialists persisted within small patches, as long as landscapes retained more than 10% of forest (>400 ha) within glacial valleys. At regional scales along the western slope of the Central Andes (Ancash, Peru), avian species richness and endemism peaked at mid-elevations (3,300 – 4,300 masl) where temperatures and precipitation were comparably moderate (i.e, intermediate levels). At continental scales, the influence of climatic factors on elevational diversity gradients differed between xeric and mesic slopes. Diversity gradients were best explained by the interaction between temperature and precipitation along the xeric slopes of the western central Andes of Peru and Chile, but primarily by temperature along mesic slopes, like the East slope to the Amazon. Based upon four climate scenarios for 2070, changes in temperature and precipitation in the western central Andes will be most severe above 2,000 masl, whereas human activities will intensify and expand below 500 and above 3,000 masl. Collectively, these results provide evidence for three overarching conclusions: 1) even fragmented or heterogeneous Polylepis landscapes have potential to adequately support avian communities in High Andean systems as well as provide habitat for numerous species of conservation concern; 2) elevational gradients in avian diversity across the Andes seem to be shaped more than by climatic than landscape or social factors; and 3) future changes in climate may profoundly alter the current avian communities, and efforts to forecast the consequences of climate change using temperature alone can produce misleading results, especially in xeric regions.La diversidad de la vida en nuestro planeta está bajo asedio. En todo el mundo, la pérdida, degradación y la fragmentación del hábitat se encuentran entre las principales amenazas para la biodiversidad, con resultados negativos exacerbados por el cambio climático. Sin embargo, nuestra escasa comprensión de los mecanismos que rigen las respuestas ecológicas al cambio global, especialmente en los sistemas montanos tropicales, limita nuestra capacidad de predecir y mitigar estas amenazas a la biodiversidad. Esta disertación aborda los efectos de la pérdida de hábitat, la fragmentación y los factores climáticos en la diversidad aviar en los Andes, con un enfoque especial en las implicaciones para el cambio climático. Específicamente, examinamos (1) la sensibilidad de las aves a la cubierta forestal y el tamaño del parche dentro de uno de los ecosistemas más amenazados de los Andes, los bosques de Polylepis, (2) cómo los factores relacionados con el clima, la configuración del paisaje y las actividades humanas a escalas regionales, configuran los patrones de la riqueza y el endemismo de las especies de aves a lo largo de los gradientes de elevación en la vertiente occidental de los Andes, (3) el grado en que las relaciones entre la elevación y la diversidad de aves a escalas continentales están influenciadas por interacciones complejas entre temperatura y precipitación, y (4) el grado en que las comunidades de aves en los Andes pueden persistir en futuros escenarios climáticos. Examinamos 88 especies de aves en 59 parches de Polylepis en cinco valles glaciares (3.300 a 4.700 m.s.n.m.) de la Cordillera Blanca (Ancash-Perú). También compilamos rangos de elevación de 212 especies dentro de la región y 2,384 en todo el continente, junto con covariables climáticas y ambientales en 16 gradientes de elevación en los Andes de Colombia, Ecuador, Perú, Bolivia, Argentina y Chile. A escalas paisajísticas, las comunidades de aves en elevaciones altas parecían adaptadas a los paisajes de Polylepis en parches naturales. La riqueza de especies fue mayor en pequeños fragmentos y áreas con cobertura forestal reducida. Los especialistas de Polylepis persistieron en pequeños parches, siempre que los paisajes retengan más del 10% de los bosques (> 400 ha) dentro de los valles glaciares. A escalas regionales a lo largo de la vertiente occidental de los Andes centrales (Ancash, Perú), la riqueza y endemismo de las especies de aves alcanzó su punto máximo en elevaciones medias (3,300 - 4,300 msnm) donde las temperaturas y las precipitaciones fueron comparativamente moderadas (es decir, niveles intermedios). A escalas continentales, la influencia de los factores climáticos en los gradientes de diversidad de elevación difería entre las pendientes xérica (aridas) y mesica (húmedas). Los gradientes de diversidad se explicaron mejor por la interacción entre la temperatura y la precipitación a lo largo de las laderas xéricas de los Andes centrales occidentales de Perú y Chile, pero principalmente por la temperatura a lo largo de las laderas mésicas, como la ladera este del Amazonas. Según cuatro escenarios climáticos para 2070, los cambios de temperatura y precipitación en los Andes centrales occidentales serán más severos por encima de los 2.000 msnm, mientras que las actividades humanas se intensificarán y expandirán por debajo de los 500 y más de 3.000 msnm. En conjunto, estos resultados proporcionan evidencia para tres conclusiones generales: 1) incluso los paisajes de Polylepis fragmentados o heterogéneos tienen el potencial de apoyar adecuadamente a las comunidades de aves en los sistemas altoandinos, así como proporcionar hábitat para numerosas especies de interés para la conservación; 2) los gradientes de elevación en la diversidad aviar en los Andes parecen estar conformados más que por factores climáticos que por paisajes o sociales; y 3) los cambios futuros en el clima pueden alterar profundamente las comunidades aviares actuales, y los esfuerzos para pronosticar las consecuencias del cambio climático utilizando solo la temperatura pueden producir resultados engañosos, especialmente en las regiones xéricas
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
MULTI-SCALE INFLUENCE OF HABITAT AND DISTURBANCE ON THE SPATIAL ECOLOGY OF MAGELLANIC WOODPECKERS (CAMPEPHILUS MAGELLANICUS)
No full text158 pagesHabitat loss, fragmentation and degradation are major threats to biodiversity, yet landscapes can be managed in ways that reduce and/or mitigate the severity of such threats. Effective landscape management, however, requires a sound understanding of ecological responses to environmental gradients, human activities, and spatial configuration of habitats elements. A large body of research has established that species perceive, select, and respond to habitat across a hierarchy of spatial scales – from foraging substrates and micro-habitats to entire landscapes – as well as through a variety of coarse-grained and fine-grained processes. Although these processes are poorly understood in many systems, we urgently need to improve our knowledge in highly threatened places like the Valdivian Rainforest ecoregion, a global biodiversity hotspot within the South American temperate forests (SATF) of Chile. Conversion of forest to agriculture and pasture has left only 30% of the original Valdivian Rainforests, with forest remnants increasingly degraded by wildfires, unsustainable logging, and firewood extraction. This dissertation examined how Magellanic woodpeckers (Campephilus magellanicus), the primary cavity excavator of these forests, responded to habitat quality and quantity, social interactions, and landscape composition and configuration. Our specific objectives were to (1) innovate a remote-sensing method to estimate quality of foraging habitat; (2) investigate how nesting and roosting cavities affected within-territory habitat use; (3) understand the implications of foraging behavior and social interactions on seed dispersal; and (4) estimate the differential contributions of historic deforestation and exotic plantations on genetic population structure. We studied four populations of Magellanic woodpeckers from 2014 to 2017, employing multiple field and computational techniques including remote-sensing, satellite telemetry, surveys of birds, behavioral observations, inventories of cavities or other signs, and spatially-explicit models. We found that decay of Nothofagaceae trees, which is both an important component and indicator of habitat quality for Magellanic woodpeckers, was highly correlated with and estimable from remotely-sensed Plant Senescence Reflectance Index. Although tree decay can profoundly affect quality and use of foraging resources, we found that space use within territories was best explained by the abundance and distribution of previously-excavated cavities for nesting or roosting. In addition, territory size declined with proximity to neighboring families and increased with non-forest cover within individual territories. Our findings also show that both the drivers and consequences of space use were partly determined by social interactions among family members. For example, displacement by adult males expanded the ecological roles of females and juveniles to include seed dispersal across much larger distances than other known dispersers in our study system. The capacity of the species to move over large distances was confirmed, in part, by the low level of genetic differentiation among Northern populations. Nevertheless, we found no evidence that current movement constraints had yet scaled up to affect population structure, which was best explained by historic deforestation. Overall, our research provides the following insights into the consequences of Patagonian forest loss, degradation, and fragmentation on Magellanic woodpeckers: (1) the quality of foraging resources may be estimated by remote sensing, (2) legacy cavities (i.e., previously excavated) are overlooked but important resources that affect space use and territoriality, (3) social interactions can mediate the delivery of ecosystem services via seed dispersal, and (4) exotic plantations represent a novel barrier to movements that may have long-term consequences for population structure
ANOTHER WAY TO TELL TIME: AN ECOLOGICAL CALENDAR FOR THE ONEIDA LAKE WATERSHED
No full text139 pagesSupplemental file(s) description: Informtion for engaging with the calendar, Ecological calendar produced from the research.Climate change poses many complex challenges at local scales. Phenology, the reoccurring patterns ofplants flowering, birds migrating, and many other ecological events responds to changing climates. Phenological observations have been collected for centuries, providing insight into the relative timing of events and how that timing shifts from year to year. Indigenous cultures have applied their own observations to decision making for even longer through ecological calendars represented in both written and oral traditions. Ecological calendars relate the timing of biophysical and phenological events to seasonal changes and the practices of ecological professionals (e.g., farmers, hunters, trappers, anglers, and more). Learning from these long-standing practices, we consider that ecological calendars may have value in building adaptive capacity among rural communities in the face of climate change. Here we collaborated with ecological professionals living in and around the Oneida Lake Watershed, located in upstate New York. Initial workshops were held with participants in 2016 to generate seasonal rounds. Follow up interviews were conducted with individuals identified using a snowball method. A follow up validation workshop was held in 2018 to verify the interpretation of interview data with the community. Finally, an ecological calendar was generated using interview data combined with and other records from scholarly publications, herbaria, and citizen science projects. We find that ecological professionals living in and around the Oneida Lake Watershed carry a wide array of knowledge that can be applied to the development of an ecological calendar. These calendars may be useful both as a framework for connecting knowledge systems and tool for informing decision making
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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