1,720,971 research outputs found
Trophic niche overlap and wild ungulate consumption by red fox and wolf in a mountain area in Italy.
No full text"Red fox (Vulpes vulpes) and wolf (Canis lupus) are two widespread opportunistic predators living in simpatry. in many areas. Nonetheless, scarce information are available on their trophic interactions. We. investigated food habits of these two carnivores in a mountain area in Italy and assessed the extent of. their trophic niche overlap, focusing on the consumption of wild ungulates. Thereby we analyzed the. content of 669 red fox scats and 253 wolf scats collected between May 2008 and April 2009. Red foxes. resulted to have a more than three times higher niche breadth than wolves. Vegetables, small mammals,. wild ungulates, and invertebrates were major items (altogether 92% of volume) of the red fox annual diet.. On the contrary wolf annual diet relied on wild ungulates (94% of volume) with wild boar (Sus scrofa). being the main food item. The degree of trophic niche overlap between the two species was found to. be low (Pianka’s O= 0.356). Diet variation between the warm and the cold seasons was limited in both. species, and higher in red fox than in wolf. The two canids appeared to use wild ungulates unevenly. being the former more selective for younger preys, smaller in size (newborn piglets and roe deer Capreolus. capreolus fawns), whereas the latter exhibited a preference for medium-sized and large ungulates. (10–35 kg wild boar and adult roe deer). Even if wild ungulates represent the main shared food category,. the different use of age\/weight classes by the two predators, together with their possible consumption as. carrions by red fox, suggests a very limited trophic competition between wolf and red fox.This study represents. a contribution to the knowledge of trophic interaction in predator–prey systems where sympatric. carnivores are present.
Trophic niche overlap and wild ungulate consumption by red fox and wolf in a mountain area in Italy
No full text
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
Mast seeding in deciduous forests of the northern Apennines (Italy) and its influence on wild boar population dynamics.
No full text"Context: Pulsed food resources may strongly affect the population dynamics of several consumer species, with consequences on the ecosystem. One of the most common pulsed resources is forest mast seeding.. Aims: We analysed mast seeding in deciduous forests in a mountainous area of northern Apennines and its effect on population dynamics of wild boar (Sus scrofa L.).. Methods: We performed a quantitative, 20-year analysis on annual seed production in Turkey oak (Quercus cerris L.), beech (Fagus sylvatica L.) and chestnut (Castanea sativa Mill.) forest stands using litter traps. The wild boar population density was estimated by means of drive censuses and hunting bag records. The role of other biotic (density of predators) and abiotic (climate) factors potentially affecting wild boar mortality was also investigated.. Results: Turkey oak and chestnut showed high levels of seed production, whereas lower levels were found in beech. The pulsed resources of chestnut and Turkey oak positively affected piglet density. Analyses also highlighted the influence of snow cover and wolves on wild boar population dynamics.. Conclusion: Wild boar can be considered a pulse rate species, the management of which can be improved by annual monitoring of seed production.
Prey selection by an apex predator: the importance of sampling uncertainty
No full textThe impact of predation on prey populations has long been a focus of ecologists, but a firm understanding of the factors
influencing prey selection, a key predictor of that impact, remains elusive. High levels of variability observed in prey
selection may reflect true differences in the ecology of different communities but might also reflect a failure to deal
adequately with uncertainties in the underlying data. Indeed, our review showed that less than 10% of studies of European
wolf predation accounted for sampling uncertainty. Here, we relate annual variability in wolf diet to prey availability and
examine temporal patterns in prey selection; in particular, we identify how considering uncertainty alters conclusions
regarding prey selection. Over nine years, we collected 1,974 wolf scats and conducted drive censuses of ungulates in Alpe
di Catenaia, Italy. We bootstrapped scat and census data within years to construct confidence intervals around estimates of
prey use, availability and selection. Wolf diet was dominated by boar (61.563.90 [SE] % of biomass eaten) and roe deer
(33.763.61%). Temporal patterns of prey densities revealed that the proportion of roe deer in wolf diet peaked when boar
densities were low, not when roe deer densities were highest. Considering only the two dominant prey types, Manly’s
standardized selection index using all data across years indicated selection for boar (mean = 0.7360.023). However,
sampling error resulted in wide confidence intervals around estimates of prey selection. Thus, despite considerable variation
in yearly estimates, confidence intervals for all years overlapped. Failing to consider such uncertainty could lead erroneously
to the assumption of differences in prey selection among years. This study highlights the importance of considering
temporal variation in relative prey availability and accounting for sampling uncertainty when interpreting the results of
dietary studies
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
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