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Food habits of two leopard species, competition, climate change and upper treeline: A way to the decrease of an endangered species
Full text linkor carnivore species, spatial avoidance is one of the evolutionary solutions to coexist in an area, especially if food habits overlap and body sizes tend to coincide. We reviewed the diets of two large cats of similar sizes, the endangered snow leopard (Panthera uncia, 16 studies) and the near-threatened common leopard (Panthera pardus, 11 studies), in Asia. These cats share ca 10,000 km2 of their mountainous range, although snow leopards tend to occur at a significantly higher altitude than common leopards, the former being a cold-adapted species of open habitats, whereas the latter is an ecologically flexible one, with a preference for woodland. The spectrum of prey of common leopards was 2.5 times greater than that of snow leopards, with wild prey being the staple for both species. Livestock rarely contributed much to the diet. When the breadth of trophic niches was compared, overlap ranged from 0.83 (weight categories) to one (main food categories). As these leopard species have approximately the same size and comparable food habits, one can predict that competition will arise when they live in sympatry. On mountains, climate change has been elevating the upper forest limit, where both leopard species occur. This means a habitat increase for common leopards and a substantial habitat reduction for snow leopards, whose range is going to be squeezed between the forest and the barren rocky altitudes, with medium-to long-term undesirable effects on the conservation of this endangered cat. © 2013 Dipartimento di Biologia, Università di Firenze, Italia
Recovery of the snow leopard in Sagarmatha (Mt. Everest) National Park: effects on main prey
No full textConsequences of predation may be particularly heavy on small populations of herbivores, especially if they are threatened with extinction. Over the 2006–2010 period, we documented the effects of the spontaneous return of the endangered snow leopard on the population of the vulnerable Himalayan tahr. The study area was an area of central
Himalaya where this cat disappeared c. 40 years before, because of persecution by man. Snow leopards occurred mainly in areas close to the core area of tahr distribution. Tahr was the staple (56.3 %) of snow leopards. After the arrival of this cat, tahr decreased by more than 2/3 from 2003 to 2010 (mainly through predation on kids). Subsequently, the density of snow leopards decreased by 60%from2007 to 2010. The main prey
of snow leopards in Asia (bharal, marmots) were absent in our study area, forcing snow leopards to specialize on tahr. The restoration of a complete prey spectrum should be favoured through reintroductions, to conserve large carnivores and to reduce exploitation of small populations of herbivores, especially if threatened
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
Common and snow leopards share prey, but not habitats: competition avoidance by large predators?
No full textResource exploitation and behavioural interference underlie competition among
carnivores. Competition is reduced by specializing on different prey and/or spatiotemporal
separation, usually leading to different food habits. We predicted that
two closely related species of large cats, the endangered snow leopard and the
near-threatened common leopard, living in sympatry, would coexist through
habitat separation and exploitation of different prey species. In central Himalaya,
we assessed (2006–2010) habitat and diet overlap between these carnivores. The
snow leopard used grassland and shrubland, whereas the common leopard
selected forest. Contrary to our prediction, snow leopard and common leopard
preyed upon similar wild (Himalayan tahr, musk deer) and domestic species (Bos
spp., dogs). Dietary overlap between snow leopard and common leopard was 69%
(yearly), 76% (colder months) and 60% (warmer months). Thus, habitat separation
should be the result of other factors, most likely avoidance of interspecific
aggression. Habitat separation may not always lead to the use of different prey.
Avoidance of interspecific aggression, rather than exploitation of different
resources, could allow the coexistence of potentially competing large predator
Pubertal exposure to estrogenic chemicals affects behavior in juvenile and adult male rats
No full textIn this paper, we tested the hypothesis that exposure to estrogens of different source and estrogenic potency at early puberty could affect the development of socio-sexual behavior in the male rat. Puberty is regarded as a second stage of the ontogenetic period, in the sexual maturation of mammals, particularly sensitive to gonadal hormone milieu. We treated animals orally, from postnatal day 23 to 30, with an environmentally compatible dose of bisphenol A (BPA, 40 microg/kg/day) and with a dosage of ethinylestradiol (EE, 0.4 microg/kg/day) comparable to the human oral contraceptives. Exposure to EE altered the temporal pattern of male sexual activity, reducing performance, in the adult animals; slight modifications, in the same direction, were observed with BPA. Short-term behavioral effects were observed in the treated animals, both with BPA and EE: the exploratory drive, directed to a stimulus object and to the environment, as well as to conspecifics, was reduced in the juveniles. Modifications in the circulating T levels were observed after treatments: T was reduced in the juveniles, both with BPA and EE. The decrement persisted in the adult animals but reached significance only in the BPA group. On the whole, effects of pubertal exposure on behavior are more marked with EE than BPA. This can be due to the much higher estrogenic potency of EE; the direction of the behavioral effects of BPA, compared with EE, is however indicative of an estrogenic mechanism
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
Restoring a keystone predator may endanger a prey species in a human-altered ecosystem: the return of the snow leopard to Sagarmatha National Park
No full textTwenty-five years ago, the snow leopard Uncia uncia, an endangered large cat, was eliminated from what is now Sagarmatha National Park (SNP). Heavy hunting pressure depleted that area of most medium–large mammals, before it became a park. After three decades of protection, the cessation of hunting and the recovery of wild ungulate populations, snow leopards have recently returned (four individuals). We have documented the effects of the return of the snow leopard on the population of its main wild prey, the Himalayan tahr Hemitragus jemlahicus, a ‘near-threatened’ caprin. Signs of snow leopard presence were recorded and scats were collected along a fixed trail (130 km) to assess the presence and food habits of the snow leopard in the Park, from 2004 to 2006. Himalayan tahr, the staple of the diet, had a relative occurrence of 48% in summer and 37% in autumn, compared with the next most frequent prey, musk deer Moschus chrysogaster (summer: 20%; autumn: 15%) and cattle (summer: 15%; autumn: 27%). In early summer, the birth rate of tahr (young-to-female ratio: 0.8–0.9) was high. The decrease of this ratio to 0.1–0.2 in autumn implied that summer predation concentrated on young tahr, eventually altering the population by removing the kid cohort. Small populations of wild Caprinae, for example the Himalayan tahr population in SNP, are sensitive to stochastic predation events and may be led to almost local extinction. If predation on livestock keeps growing, together with the decrease of Himalayan tahr, retaliatory killing of snow leopards by local people may be expected, and the snow leopard could again be at risk of local extinction. Restoration of biodiversity through the return of a large predator has to be monitored carefully, especially in areas affected by humans, where the lack of important environmental components, for example key prey species, may make the return of a predator a challenging event
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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