1,720,965 research outputs found
Erhaltungszustand und Ökologie des Nigeria–Kamerun Schimpansen im Kom–Wum Waldreservat, Nord–West Region, Kamerun
No full textIncreased human activity, such as deforestation, is a major driver of biodiversity loss worldwide. In Cameroon, these activities could ultimately threaten the survival of the Nigeria-Cameroon chimpanzee, but knowledge of their abundance and ecology in the Kom - Wum Forest Reserve in Cameroon is still lacking. This research aimed to estimate the population size of this chimpanzee subspecies and assess threats, investigate nesting behaviour, identify suitable habitats, determine feeding habits and document the tools used for food acquisition. Research was conducted using line transects during two seasons: wet (May-September 2018) and dry (November 2019-March 2020). Population size and threats were assessed by georeferencing signs of chimpanzees and human activity along line transects. Nesting behaviour was investigated by recording the characteristics of nesting trees along line transects and mapping their distribution in ArcGIS. Suitable habitat was identified by relating chimpanzee presence signs to local environmental variables related to relief, vegetation and human impact using the Maximum Entropy Species Distribution Model (MaxEnt). Feeding habits were investigated by direct examination of chimpanzee faeces, and tool use was documented by observation and measurement of tools in situ. The reserve is home to up to 83 chimpanzees. Signs of chimpanzee activity were significantly higher in mature forest than in secondary forest, and above 1000 m than below 1000 m. Hunting was the main threat to chimpanzees, and the occurrence of chimpanzee signs decreased significantly with increasing human activity. Chimpanzees preferred tall, mature forest trees at higher elevations with slopes for nesting, and avoided areas near villages and bare land. Only 8% of the study area was suitable chimpanzee habitat. Fruit dominated the chimpanzees' diet, but they also consumed leaves and fruit pith, especially during the dry season. There was also indirect evidence that chimpanzees used tools to consume driver ants (genus Dorylus). Seasonality significantly affected the size of tools used by chimpanzees for driver ant predation. They preferred to use thicker and shorter tools for driver ant predation during the rainy season, whereas longer and thinner tools were used during the dry season. The results of this research highlight the need to reduce poaching and deforestation to protect the remaining chimpanzee population and suitable habitat in the reserve and surrounding unprotected forest. High-elevation and mature forests are critical for chimpanzee conservation and should be a high priority for protection. This research has filled the knowledge gap on what little was known about the abundance and ecology of Nigeria-Cameroon chimpanzees.Die erhöhte menschliche Aktivität, wie etwa die Abholzung, ist weltweit ein bedeutender Faktor für den Verlust an Biodiversität. In Kamerun könnten diese Aktivitäten letztendlich das Überleben des Nigeria-Kamerun-Schimpansen gefährden, doch das Wissen über ihre Häufigkeit und Ökologie im Kom-Wum-Waldreservat in Kamerun ist noch unzureichend. Diese Forschung zielt darauf ab, die Populationsgröße dieser Schimpansen-Unterart zu schätzen, Bedrohungen zu bewerten, das Nestbauverhalten zu untersuchen, geeignete Lebensräume zu identifizieren, Fressgewohnheiten festzustellen und Werkzeuge zur Nahrungsbeschaffung zu dokumentieren. Die Forschung nutzte Linientransekte in zwei Jahreszeiten: Regenzeit und Trockenzeit. Populationsgröße und Bedrohungen wurden durch die Georeferenzierung von Schimpansen- und menschlichen Aktivitätszeichen entlang der Linientransekte bewertet. Das Nestbauverhalten wurde durch Aufzeichnung der Merkmale von Nestbäumen entlang der Linientransekte untersucht und in ArcGIS kartiert. Geeignete Lebensräume wurden durch die Beziehung von Schimpansenpräsenzzeichen zu lokalen Umweltvariablen im Zusammenhang mit Relief, Vegetation und menschlichem Einfluss mithilfe des Maximum Entropy Species Distribution Model (MaxEnt) identifiziert. Fressgewohnheiten wurden durch direkte Untersuchung von Schimpansenkot erforscht, und der Werkzeuggebrauch wurde durch Beobachtung und Messung von Werkzeugen vor Ort dokumentiert. Das Reservat beherbergt bis zu 83 Schimpansen. Zeichen für Schimpansenaktivität waren signifikant häufiger im ausgewachsenen Wald als im Sekundärwald und über 1000 m höher als unter 1000 m. Die Hauptbedrohung für Schimpansen war die Jagd, und das Auftreten von Schimpansenzeichen nahm signifikant mit zunehmender menschlicher Aktivität ab. Schimpansen bevorzugten hohe, ausgewachsene Waldbäume in höheren Lagen mit Neigungen zum Nestbau und mieden Gebiete in der Nähe von Dörfern und Brachland. Nur 8% des Untersuchungsgebiets waren geeigneter Schimpansenlebensraum. Obst dominierte die Ernährung der Schimpansen, doch sie konsumierten auch Blätter und Fruchtsaft, besonders während der Trockenzeit. Es gab auch indirekte Hinweise darauf, dass Schimpansen Werkzeuge zur Konsumierung von Treiberameisen verwendeten. Die Jahreszeit beeinflusste die Größe der Werkzeuge für die Treiberameisenprädation signifikant. Während der Regenzeit bevorzugten sie dickere und kürzere Werkzeuge, während sie während der Trockenzeit längere und dünnere Werkzeuge nutzten. Die Ergebnisse dieser Forschung unterstreichen die Notwendigkeit, Wilderei und Abholzung zu reduzieren, um die verbleibende Schimpansenpopulation und geeigneten Lebensraum im Reservat und den umliegenden ungeschützten Wäldern zu schützen. Hochgelegene und ausgewachsene Wälder sind entscheidend für den Schutz der Schimpansen und sollten eine hohe Priorität für den Schutz haben. Diese Forschung hat die Wissenslücke über die Häufigkeit und Ökologie der Nigeria-Kamerun-Schimpansen geschlossen
Human Activity and Forest Degradation Threaten Populations of the Nigeria–Cameroon Chimpanzee (Pan troglodytes ellioti) in Western Cameroon
No full textAbstract
Increased human activities such as commodity-led deforestation, extension of agriculture, urbanization, and wildfires are major drivers of forest loss worldwide. In Cameroon, these activities cause a loss of suitable primate habitat and could ultimately threaten the survival of chimpanzees (
Pan troglodytes
). We derived independent estimates of the population size of the Endangered Nigeria–Cameroon chimpanzee (
Pan troglodytes ellioti
) in Kom-Wum Forest Reserve, Cameroon, and surrounding unprotected forest areas through 1) direct observations, 2) camera trapping, 3) distance sampling, 4) marked nest counts, and 5) standing crop nest counts. In addition, we georeferenced signs of chimpanzee and human activity along line transects. We used a generalized linear mixed model to predict the occurrence of chimpanzees in response to edge length (measured as the perimeter of core forest patches), core area of forest patches (measured as area of forest patches beyond an edge width of 100 m), habitat perforation (measured as the perimeter of nonforested landscape within core forest patches), patch size(measured as area of forest patches), and forest cover. Chimpanzee density estimates ranged from 0.1 (direct observation) to 0.9 (distance sampling) individuals km
−2
depending on estimation method with a mean nest group size of 7 ± 5.4 (SD). The mean encounter rate for signs of chimpanzee activity was significantly higher in mature forests (2.3 signs km
−1
) than in secondary forests (0.3 signs km
−1
) and above 1000 m elevation (4.0 signs km
−1
) than below 1000 m (1.0 signs km
−1
). The mean encounter rate for signs of human activity was significantly higher in secondary (8.0 signs km
−1
) than in mature forests (0.9 signs km
−1
). Secondary forests, habitat perforation, and edge length had a significant negative effect on the occurrence of chimpanzee signs. Overall, human activity and forest degradation affected the number of observed chimpanzee signs negatively. Regular antipoaching patrols and reforestation programs in degraded areas could potentially reduce threats to populations of endangered species and may increase suitable habitat area
Tool use by Nigeria-Cameroon chimpanzees for driver ant predation in Kom-Wum Forest Reserve, North-West Region Cameroon
No full textEnvironmental and anthropogenic effects on the nesting patterns of Nigeria–Cameroon chimpanzees in North‐West Cameroon
No full textRufford Foundation https://doi.org/10.13039/10000746
Mapping suitable habitat for Nigeria–Cameroon chimpanzees in Kom-Wum Forest Reserve, North-Western Cameroon
No full textAbstract Great apes lose suitable habitats required for their reproduction and survival due to human activities across their distribution range in Africa. Little is known about habitat suitability of the Nigeria–Cameroon chimpanzee [ Pan troglodytes ellioti (Matschie, 1914)], particularly for populations inhabiting forest reserves in North-West Cameroon. To address this knowledge gap, we employed a common species distribution model (MaxEnt) to map and predict suitable habitats for the Nigeria–Cameroon chimpanzee in Kom-Wum Forest Reserve, North-West Cameroon, based on environmental factors that potentially affect habitat suitability. We related these environmental factors to a dataset of chimpanzee occurrence points recorded during line transect and reconnaissance (recce) surveys in the forest reserve and surrounding forests. Up to 91% of the study area is unsuitable for chimpanzees. Suitable habitats only represented 9% of the study area, with a high proportion of highly suitable habitats located outside the forest reserve. Elevation, secondary forests density, distance to villages and primary forests density were the most important predictors of habitat suitability for the Nigeria–Cameroon chimpanzee. The probability of chimpanzee occurrence increased with elevation, secondary forest density and distance from villages and roads. Our study provides evidence that suitable chimpanzee habitat in the reserve is degraded, suggesting that efforts to maintain protected areas are insufficient. The reserve management plan needs to be improved to conserve the remaining suitable habitat and to avoid local extinction of this endangered subspecies.Rufford Foundation http://dx.doi.org/10.13039/100007463International Foundation for Science http://dx.doi.org/10.13039/100004413Brandenburgische TU Cottbus-Senftenber
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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