1,720,958 research outputs found
Spatial and temporal niche overlap of aardwolves and aardvarks in Serengeti National Park, Tanzania
No full text<p>Species interactions can influence species distributions, but mechanisms mitigating competition or facilitating positive interactions between ecologically similar species are often poorly understood. Aardwolves (<em>Proteles cristata</em>) and aardvarks (<em>Orycteropus afer</em>) are nocturnal, insectivorous mammals that co-occur in eastern and southern Africa, and knowledge of these species is largely limited to their nutritional biology. We used aardwolf and aardvark detections from 106 remote cameras during 2016–2018 to assess their spatial and temporal niche overlap in the grasslands of Serengeti National Park, Tanzania. Using a multispecies occupancy model, we identified a positive interaction between occupancy probabilities for aardwolves and aardvarks. Slope, proportion of grassland, and termite mound density did not affect occupancy probabilities of either species. Probability of aardwolf, but not aardvark, occupancy increased with distance to permanent water sources, which may relate to predation risk avoidance. Diel activity overlap between aardwolves and aardvarks was high during wet and dry seasons, with both species being largely nocturnal. Aardwolves and aardvarks have an important ecological role as termite consumers, and aardvarks are suggested to be ecosystem engineers. Our results contribute to a better understanding of the spatial and temporal niche of insectivores like aardwolves and aardvarks, suggesting high spatial and temporal niche overlap in which commensalism occur, whereby aardwolves benefit from aardvark presence through increased food accessibility.</p><p>We collected data during August 2016–June 2018 using 106 remote cameras (Stealth Cam, model N45NG; Irving, Texas, USA). Nearest distance between cameras was 3,000 m for 63 cameras and 4,225 m for 43 cameras (Figure 1). We attached cameras to metal stakes 50-cm above ground and cleared vegetation in front of cameras. We programmed cameras to record 3-image bursts at each detection with a 30-second delay and inspected each about every 6 weeks. Because of staggered camera installations, we extracted data for a period of 70 consecutive days from each camera (hereafter a "camera-period") during 26 August 2016–1 January 2018, and a second 70-day camera-period for 77 cameras during 22 January 2017–30 June 2018. Overlap between the two periods of data collection occurred due to staggered camera installation. Most (95%) data were obtained during September 2016–February 2018. Each 70-day camera-period was associated with a season (wet season, November-May; dry season, June-October). If a camera-period overlapped two seasons, we split the data by season into two separate, shorter camera-periods each entirely with one season.</p>
Spatial and temporal niche overlap of aardwolves and aardvarks in Serengeti National Park, Tanzania
No full text<p>Species interactions can influence species distributions, but mechanisms mitigating competition or facilitating positive interactions between ecologically similar species are often poorly understood. Aardwolves (<em>Proteles cristata</em>) and aardvarks (<em>Orycteropus afer</em>) are nocturnal, insectivorous mammals that co-occur in eastern and southern Africa, and knowledge of these species is largely limited to their nutritional biology. We used aardwolf and aardvark detections from 106 remote cameras during 2016–2018 to assess their spatial and temporal niche overlap in the grasslands of Serengeti National Park, Tanzania. Using a multispecies occupancy model, we identified a positive interaction between occupancy probabilities for aardwolves and aardvarks. Slope, proportion of grassland, and termite mound density did not affect occupancy probabilities of either species. Probability of aardwolf, but not aardvark, occupancy increased with distance to permanent water sources, which may relate to predation risk avoidance. Diel activity overlap between aardwolves and aardvarks was high during wet and dry seasons, with both species being largely nocturnal. Aardwolves and aardvarks have an important ecological role as termite consumers, and aardvarks are suggested to be ecosystem engineers. Our results contribute to a better understanding of the spatial and temporal niche of insectivores like aardwolves and aardvarks, suggesting high spatial and temporal niche overlap in which commensalism occur, whereby aardwolves benefit from aardvark presence through increased food accessibility.</p><p>We collected data during August 2016–June 2018 using 106 remote cameras (Stealth Cam, model N45NG; Irving, Texas, USA). Nearest distance between cameras was 3,000 m for 63 cameras and 4,225 m for 43 cameras (Figure 1). We attached cameras to metal stakes 50-cm above ground and cleared vegetation in front of cameras. We programmed cameras to record 3-image bursts at each detection with a 30-second delay and inspected each about every 6 weeks. Because of staggered camera installations, we extracted data for a period of 70 consecutive days from each camera (hereafter a "camera-period") during 26 August 2016–1 January 2018, and a second 70-day camera-period for 77 cameras during 22 January 2017–30 June 2018. Overlap between the two periods of data collection occurred due to staggered camera installation. Most (95%) data were obtained during September 2016–February 2018. Each 70-day camera-period was associated with a season (wet season, November-May; dry season, June-October). If a camera-period overlapped two seasons, we split the data by season into two separate, shorter camera-periods each entirely with one season.</p>
SPATIAL ECOLOGY OF GRAY WOLVES (CANIS LUPUS) IN THE WESTERN GREAT LAKES REGION IN RESPONSE TO ANTHROPOGENIC DISTURBANCE
No full textLarge carnivores tend to avoid humans and their activities spatially and temporally, yet often experience high rates of anthropogenic mortality and their conservation frequently depends on coexistence with humans. I investigated how human landscape disturbances influences landscape use by gray wolves (Canis lupus) in the western Great Lakes region of the United States. Specifically, I investigated whether landscape use by wolves has changed temporally, whether it differs among individuals, and how human disturbances may affect the future distribution of gray wolves. I characterized wolf recolonization of the western Great Lakes region during 1989\u20132020 by investigating whether the relationship between wolf habitat suitability and two indices of human disturbance, human population density and proportions of agricultural land cover, has changed during this period. I also modeled habitat selection for the western Great Lakes region, distinguishing between territorial and non-territorial wolves and conducted a subsequent connectivity analysis. Finally, I assessed wolf recolonization potential throughout their former range in the eastern USA by modeling habitat suitability and connectivity potential. During 1989\u20132020, wolves occupied areas with progressively higher levels of human disturbance, resulting in an estimated 35% increase in wolf habitat across Minnesota, Wisconsin, and Michigan, though range expansion appeared to slow over time. Habitat selection of territorial and non-territorial wolves was similar and connectivity analysis suggested limited habitat connectivity due to human landscape disturbance, constrained recolonization of suitable areas within the western Great Lakes region. I estimated 65.3% of former range in the eastern USA is currently unsuitable for wolves, but identified five unoccupied areas in the eastern USA that could maintain viable wolf populations. However, connectivity between current and potential wolf range appears limited due to high human disturbance and the presence of the Great Lakes. This work demonstrates an apparent range stabilization of wolves in the Great Lakes region, where little unoccupied habitat remains available, but there appears limited potential for further natural recolonization of unoccupied habitat throughout the eastern United States. This can inform policy discussions such as the desirability of human-assisted recolonization of additional historical range, and the accomplishment of targets set when wolves received federal protection.Thesis (Ph.D.)--Michigan State University. Fisheries and Wildlife - Doctor of Philosophy, 2023Includes bibliographical reference
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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