1,720,974 research outputs found
Polar Bear Predatory Behaviour toward Molting Barnacle Geese and Nesting Glaucous Gulls on Spitsbergen
Get PDFA polar bear (Ursus maritimus) was observed stalking and chasing a flock of adult flightless barnacle geese (Branta leucopsis) in a coastal bay in Hornsund, southwest Spitsbergen. Before chasing the geese, the polar bear appeared to make use of the cover provided by a rocky pier in order to swim close to them. Immediately after that unsuccessful attempt, the bear plundered a glaucous gull (Larus hyperboreus) nest situated on coastal rock and captured three nestlings. These observations are the first documented instances of a polar bear hunting for barnacle goose and glaucous gull and provide additional evidence of the use of terrestrial prey by polar bears during the season of minimal ice extent.Un ours polaire (Ursus maritimus) a été observé en train de traquer et de pourchasser une bande de bernaches nonnettes (Branta leucopsis) coureuses adultes dans une baie côtière de Hornsund, dans le sud-ouest de Spitsbergen. Avant d’avoir chassé les bernaches, l’ours polaire semblait s’être servi d’un quai rocailleux pour se cacher et nager près des bernaches. Immédiatement après cette tentative échouée, l’ours a pillé un nid de goélands bourgmestres (Larus hyperboreus) situé sur un rocher côtier et a capturé trois oisillons. Ces observations, les premiers exemples de bernaches nonnettes et de goélands bourgmestres pourchassés par un ours polaire, fournissent d’autres preuves selon lesquelles les ours polaires ont des proies terrestres pendant la saison de l’étendue minimale de glace
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
Polar bears observed climbing steep slopes to graze on scurvy grass in Svalbard
No full textIt is well known that polar bears feed on vegetation. Here, I report novel observations of polar bears grazing on polar scurvy grass (Cochlearia groenlandica) at the foot of a large seabird colony on a cliff on Spitsbergen, Svalbard, in the summers of 2005, 2006, 2009, 2014 and 2015. Why they choose such energy-costly climbing to feed on plants is not clear. One possibility is that they may be suffering from vitamin C deficiency and are searching for this particular plant, which has a high level of this vitamin. Another, but not exclusive reason, is that vegetation containing scurvy grass is abundant enough to be efficiently grazed by such unspecialized plant-eaters as polar bears only on such relatively inaccessible, steep slopes below seabird colonies. Most of the lowland and gently sloping tundra areas in Svalbard are overgrazed by geese and reindeer, the populations of which have increased considerably as a consequence of climate amelioration. Large seabird colonies are known to attract animals from different trophic levels, but this is the first description of their attractiveness to polar bears as grazing areas
Glaucous Gulls Kleptoparasiting Arctic Foxes in Magdalenefjorden, NW Spitsbergen
Get PDFObservations were made of glaucous gulls (Larus hyperboreus) stealing little auks (Alle alle) stored in a den by arctic foxes (Vulpes lagopus) in Magdalenefjorden, northwest Spitsbergen. Before stealing the spoil, the gulls observed and followed foxes transporting little auks hunted in a nearby colony. Skill in detecting and successfully taking over the food cached by arctic foxes may help glaucous gulls to survive critical periods of lowered prey availability and enhanced energy demands, such as the little auk incubation period, when the auks are well hidden in the nests and inaccessible for gulls feeding their own large nestlings. These observations are the first documented instances of the glaucous gulls kleptoparasiting arctic foxes and provide additional evidence of the complex nature of interactions occurring between these two opportunistic Arctic predators.On a observé des goélands bourgmestres (Larus hyperboreus) en train de voler des mergules nains (Alle alle) qui avaient été placés dans une tanière par des renards arctiques (Vulpes lagopus) à Magdalenefjorden, dans le nord-ouest de Spitsbergen. Avant de voler les mergules, les goélands observaient les renards et les suivaient en train de transporter les mergules nains chassés dans une colonie située tout près. L’aptitude à détecter la nourriture cachée par les renards arctiques et à s’en accaparer pourrait aider les goélands bourgmestres à survivre pendant les périodes critiques où il y a peu de proies et où le besoin en énergie est plus grand, telle que la période d’incubation des mergules nains, soit lorsque les mergules sont bien cachés dans les nids et qu’ils ne sont pas accessibles aux goélands qui nourrissent leurs propres nichées d’envergure. Ces observations constituent les premiers cas documentés de goélands bourgmestres en train de faire du cleptoparasitisme chez le renard arctique, en plus de présenter des preuves supplémentaires de la nature complexe des interactions entre ces deux prédateurs opportunistes de l’Arctique
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
The polar bear Ursus maritimus feeding in a seabird colony in Frans Josef Land
No full textDuring the second half of August 1992 polar bears were observed feeding intensively in the little auk Alle alle colony on Rubini Rock, Hooker Island, Frans Josef Land. They dug out nests eating eggs, chicks and adult birds. Their activity results in both worsening the breeding conditions and decreasing the breeding success of the little auks. The polar bear has not earlier been known as a little auk predator
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
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