1,720,959 research outputs found
Effects of a new waste collection policy on the population of yellow-legged gulls, Larus michahellis, in the historic centre of Venice (Italy)
No full textUrban sprawl represents one of the most critical threats to biodiversity leading to the decline of rare and specialist species and the proliferation of a few dominant generalist ones. Among the winners there is the yellow-legged gull, Larus michahellis, which has recently colonised towns, nesting on the roofs of buildings and feeding on urban waste by spreading the contents of garbage bags on the streets. This situation has been recently documented in the historic centre of Venice (Italy) where it led to negative environmental impact and serious consequences in terms of urban hygiene. To counter such problems, the public company responsible for managing the urban waste in the Venice municipality established a new waste collection policy in the city to prevent accumulation of rubbish in the streets and limit the amount of trophic resources available for the species. We performed a monitoring program of the urban population of yellow-legged gulls and used generalized linear models to investigate the effectiveness of the new waste collection system on reducing the amount of waste in the streets and its effect on the target species. Results revealed a statistically significant positive correlation between urban waste and gulls and a significant effect of the new policy in lowering these two variables. Open areas, strongly frequented, with food and beverage vendors and illegal dumps were also highlighted as the main contributors to the presence of yellow-legged gulls. Such information can be used by local authorities to plan specific interventions to reduce the attractiveness of the city to gulls
Male Golden-collared Manakins Manacus vitellinus do not adapt their courtship display to spatial alteration of their court
No full textMale Golden-collared Manakins Manacus vitellinus perform an elaborate courtship display composed of acrobatic jumps between saplings delimiting a court on the forest floor. Males rehearse their displays for hours until they are executed with amazing precision and speed. Here we investigated the plasticity of the display by examining whether males modify their choreography in response to a disturbance, such as when a small branch is placed against one of the saplings. Male Manakins performed displays that were longer and lacked a key element that invites females to copulate, supporting the hypothesis that males learn a specific sequence of moves to build their choreography. © 2011 The Authors. Ibis © 2011 British Ornithologists' Union
Floating rafts as breeding habitats for the Common tern, Sterna hirundo. Colonization patterns, abundance and reproductive success in Venice Lagoon
Full text linkThe Venice lagoon hosts the 15% of the entire Italian
breeding population of Common terns, Sterna hirundo, highlighting the
great value of the area for this species. However, in the last 25 years, a
substantial decline of Common terns has been detected in the Lagoon,
which culminated in 2008. The main causes of this negative trend
were the loss of salt marsh habitats, where terns typically breed in the
Venice lagoon. This was due to the increase in the mean sea level and
the greater frequency of high tides during the reproductive period with
consequent flooding of their breeding sites; competition with yellowlegged
gulls (Larus michahellis), predation and human disturbance. As
a preliminary experimental approach to counter the depletion of the
species and favour its recovery, we performed a habitat loss compensation
project by setting up four floating rafts (3x2m), covered by two
different types of substrate (sandy and vegetal substrate). This was to
function as an artificial nesting site safe from flooding, positioned in
a protected internal wetland area of the Venice lagoon, Valle Averto
(Sourthern Lagoon). We studied the colonization patterns of the rafts
and the reproductive success of Common tern breeding pairs during the
2014 and 2015 breeding seasons. We also investigated those environmental
and structural variables that could favour the use of the rafts and
the nesting success of the species. In both years, the rafts were successfully
colonized and used by terns for nesting. Our results also indicated
higher temperature, lower rainfall and greater distance from the shore
as the main habitat factors favouring the occurrence and the reproductive
success of the breeding pairs, while a windrow of dead plants was
indicated as the preferred substrate for covering rafts in order to make
them more attractive. The results provided some suggestions for successful
restoration plans to be developed in similar lagoon areas
Gli effetti di una nuova politica gestionale dei rifiuti sulla popolazione di gabbiano reale a Venezia
No full textIn anni recenti a Venezia è stata ampiamente documentata l’abilità dei gabbiani reali (Larus michahellis), nel rompere i sacchetti dell’immondizia lasciati per la strada da cittadini e turisti, disseminandone il contenuto e provocando delle gravi conseguenze sul decoro urbano e sull’ambiente. Per fare fronte a tali criticità, l’Azienda Municipalizzata per la raccolta dei rifiuti ha avviato, a partire da ottobre 2016, un nuovo modello ‘porta a porta’ che ne prevede la consegna agli operatori ecologici o il conferimento presso i punti mobili e temporanei situati in diverse zone della città. Tale politica gestionale è stata introdotta nei sestieri in diversi periodi dell’anno per consentire agli abitanti di abituarsi radualmente alle nuove direttive. Parallelamente all’avvio del nuovo protocollo di raccolta dei rifiuti in tre sestieri campione, abbiamo condotto, tra marzo 2017 e novembre 2018, un monitoraggio della popolazione urbana di gabbiano reale per studiarne gli effetti sull’abbondanza e distribuzione della specie ed ottenere una stima aggiornata per il centro storico di Venezia. Il monitoraggio, eseguito mediante la tecnica del Distance sampling, ha consentito di documentare sia lo stato antecedente l’avvio del nuovo modello di raccolta, sia quello successivo alla sua introduzione ed ha indicato la presenza di oltre 400 coppie nel giugno 2018, contro le 24 censite nel 2005. A seguito di tale cambio, abbiamo registrato un calo significativo dei rifiuti per la strada, con un effetto significativo e negativo sulla presenza e abbondanza dei gabbiani reali, che mostrano ora una densità più elevata negli spazi aperti, come i campi e le piazze della città, con attività alimentari e un elevato flusso turistico, nonché nei luoghi in cui vengono abbandonati i rifiuti. Tali informazioni risultano utili per predisporre un piano di gestione della specie basato su una conoscenza puntuale e aggiornata della realtà urbana
Birds and noise: the Mose yards case (lagoon of Venice, Italy)
No full textResults from the study of the effects of noise emissions, arising from the construction activities of the MoSE yards on birds living in the surrounding areas are here presented. None of the three parameters selected are descriptors of the state of the bird community was significantly influenced by the pile driving activities, which constitute the primary source of noise disturbance. Again, no significant differences were found in the index of relative abundance of the two bird communities, before and after the noise provoked by the construction works
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
- …
