1,720,963 research outputs found
An assessment of avifauna in a recovering lowland forest at Kinabalu National Park, Malaysian Borneo
No full textPegan, Teresa M., Gulson-Castillo, Eric R., Biun, Alim, Byington, Joseph I., Moyle, Robert G., Yu, Fred Tuh Yit, Wood, Eric M., Winkler, David W., Sheldon, Frederick H. (2018): An assessment of avifauna in a recovering lowland forest at Kinabalu National Park, Malaysian Borneo. Raffles Bulletin of Zoology 66: 110-131, DOI: 10.5281/zenodo.535855
Fig. 2. A in An assessment of avifauna in a recovering lowland forest at Kinabalu National Park, Malaysian Borneo
No full textFig. 2. A species accumulation curve (from the 2014 Cornell expedition, lowland species only). This curve demonstrates that we continued to accumulate new species throughout the entire time spent in the field.Published as part of Pegan, Teresa M., Gulson-Castillo, Eric R., Biun, Alim, Byington, Joseph I., Moyle, Robert G., Yu, Fred Tuh Yit, Wood, Eric M., Winkler, David W. & Sheldon, Frederick H., 2018, An assessment of avifauna in a recovering lowland forest at Kinabalu National Park, Malaysian Borneo, pp. 110-131 in Raffles Bulletin of Zoology 66 on page 113, DOI: 10.5281/zenodo.535855
Fig. 1. A in An assessment of avifauna in a recovering lowland forest at Kinabalu National Park, Malaysian Borneo
No full textFig. 1. A map of the area around the Serinsim Substation headquarters showing trails, rivers, and approximate habitat boundaries. 1 = "Primary" forest: unburned forest starting about one km from headquarters; 2 = "Secondary" forest: taller hillside secondary forest from 200–450 m; 3 = forest recovering from 1997 fires, adjacent to the headquarters compound at 200 m; 4 = Open area and river edge at the substation headquarters at 200 m.Published as part of Pegan, Teresa M., Gulson-Castillo, Eric R., Biun, Alim, Byington, Joseph I., Moyle, Robert G., Yu, Fred Tuh Yit, Wood, Eric M., Winkler, David W. & Sheldon, Frederick H., 2018, An assessment of avifauna in a recovering lowland forest at Kinabalu National Park, Malaysian Borneo, pp. 110-131 in Raffles Bulletin of Zoology 66 on page 111, DOI: 10.5281/zenodo.535855
Bird Magnetoreception Across Scales: From Comparative Neuroanatomy to Macroecology
No full textMagnetoreception, the ability to detect and use Earth's magnetic fields for navigation and orientation, is a mysterious sensory system. Despite decades of research, scientists do not know the physiological mechanisms by which it functions in birds. Most magnetoreception research is done in carefully controlled experiments with captive model organisms. My dissertation focused on expanding the scales at which we research magnetoreception in birds to understudied parts of the avian tree of life and larger spatiotemporal contexts. This allows me to test hypotheses regarding the use of magnetoreception in more complex environments, as well as the evolution of magnetoreception relative to seasonal migration.
Accurate navigation is critical for successful seasonal migration. Migration has been gained and lost many times over evolutionary history, but it is unclear how many of the components of the migratory phenotype, including magnetoreception, are retained when migration re-evolves. Two of my chapters compared magnetoreception in three passerine bird families that evolved or re-evolved migration independently, thereby testing the relationship between magnetoreception and the evolution of migration.
In chapter 2, I tested for magnetic compass orientation behavior in Tyrannidae, Turdidae, and Vireonidae. Flycatchers (Tyrannidae) had never been tested for magnetic orientation and lack cryptochrome 4 (Cry4), a protein thought to be critical for magnetoreception through a visual pathway. None of my study species showed a consistent magnetic response, making our results challenging to interpret. However, I unexpectedly found that flycatchers and vireos (Vireonidae) seemed more liable to show phototactic behavior than thrushes (Turdidae), despite evidence for an opposite relationship with phototaxis when the same birds migrate in the wild.
In chapter 3, I compared brain stimulation patterns linked to magnetoreception in the same three families. Cluster N is a region in the visual wulst in the forebrain that is active at night in night-migratory songbirds. I exposed birds to a day/night and a magnetic stimulation treatment and measured Egr-1 expression, a protein indicative of neurostimulation, using immunohistochemistry. All three bird families showed cluster N activation patterns at night and little indication of a magnetic response. Cluster N activation in flycatchers is especially surprising because cluster N is thought to be linked to Cry4, which flycatchers lack. My results instead suggested that all major radiations in Passeriformes show cluster N activation. I argue that while cluster N is tightly linked to nocturnal migration, its link to magnetoreception requires further investigation, especially given its activation in flycatchers.
In chapter 4, I tested for effects of space weather-induced geomagnetic disturbances on nocturnal bird migration. Large impacts of magnetized energy from the Sun can destabilize Earth's magnetic field, presumably making it less reliable for navigation. I measured the intensity, direction, and altitude of nocturnal bird migration using weather radar data and compared it to a radar-specific custom magnetic disturbance index. Using two complementary statistical methods, I found decreases in migration intensity, or the number of birds migrating, in the spring and fall during large geomagnetic disturbances. In the fall, I also found that birds spent less energy flying against the wind when it was overcast during strong geomagnetic disturbances, suggesting that they might not be able to navigate as effectively without other navigation cues. This study allowed me to examine macroecological effects of magnetoreception in a complex environment at a larger spatial and ecological scale than previously possible.PhDEcology and Evolutionary BiologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/194473/1/ergc_1.pd
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
Rapid adjustments of migration and life history in hemisphere-switching cliff swallows
No full textMany aspects of bird migration are necessarily innate.1 However, the extent of deterministic genetic control, environmental influence, and individual decision making in the control of migration remains unclear.2–8 Globally, few cases of rapid and dramatic life-history changes resulting in novel migration strategies are known. An example is latitudinal trans-hemispheric breeding colonization, whereby a subpopulation suddenly begins breeding on its non-breeding range.9–13 These life-history reversals demand concomitant changes in the timing of migration, feather molt, and breeding if the population is to remain viable.13 Cliff swallows, Petrochelidon pyrrhonota, are long-distance migrants that breed in North America and spend the non-breeding season mostly in South America.14 However, in 2015, a small population switched hemispheres by breeding successfully in Argentina,9 over 8,000 km from the nearest potential source, after presumably failed attempts.15,16 This provided a unique chance to characterize the early mechanisms of change in migratory behavior and phenology and to assess the possibility of double breeding. We tracked cliff swallows with geolocators following their second and fourth breeding seasons in Argentina, documenting inverted seasonality, three new migratory patterns and non-breeding areas (North America, Mesoamerica, and South America), and a shift of molt phenology by approximately 6 months, all possibly arising within a single generation. These birds did not practice migratory double breeding, although some spent the boreal summer in the traditional breeding range. Our data show that fundamental phenological changes occurred very rapidly during colonization and that phenotypic plasticity can underlie profound changes in the life histories of migratory birds.Fil: Areta, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del Noroeste Argentino. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto de Bio y Geociencias del Noroeste Argentino; ArgentinaFil: Salvador, Sergio A.. Investigador Autónomo; ArgentinaFil: Gandoy, Facundo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico NOA Sur. Instituto de Ecología Regional. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; ArgentinaFil: Bridge, Eli S.. University of Oklahoma. Oklahoma Biological Survey; Estados UnidosFil: Gorleri, Fabricio Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del Noroeste Argentino. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto de Bio y Geociencias del Noroeste Argentino; ArgentinaFil: Pegan, Teresa M.. Cornell University; Estados Unidos. University of Michigan; Estados UnidosFil: Gulson Castillo, Eric R.. Cornell University; Estados Unidos. University of Michigan; Estados UnidosFil: Hobson, Keith A.. Western University; CanadáFil: Winkler, David Ward. Cornell University; Estados Unido
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
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
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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