1,721,070 research outputs found
Shark personalities? Repeatability of social network traits in a widely distributed predatory fish
Get PDFInterest in animal personalities has generated a burgeoning literature on repeatability in individual traits such as boldness or exploration through time or across different contexts. Yet, repeatability can be influenced by the interactive social strategies of individuals, for example, consistent inter-individual variation in aggression is well documented. Previous work has largely focused on the social aspects of repeatability in animal behaviour by testing individuals in dyadic pairings. Under natural conditions, individuals interact in a heterogeneous polyadic network. However, the extent to which there is repeatability of social traits at this higher order network level remains unknown. Here, we provide the first empirical evidence of consistent and repeatable animal social networks. Using a model species of shark, a taxonomic group in which repeatability in behaviour has yet to be described, we repeatedly quantified the social networks of ten independent shark groups across different habitats, testing repeatability in individual network position under changing environments. To understand better the mechanisms behind repeatable social behaviour, we also explored the coupling between individual preferences for specific group sizes and social network position. We quantify repeatability in sharks by demonstrating that despite changes in aggregation measured at the group level, the social network position of individuals is consistent across treatments. Group size preferences were found to influence the social network position of individuals in small groups but less so for larger groups suggesting network structure, and thus, repeatability was driven by social preference over aggregation tendency
The effect of formation swimming on tailbeat and breathing frequencies in killer whales
Get PDFIn many aquatic taxa, formation traveling can reduce the energetic expenditure of locomotion by exploiting the vorticity trails shed by neighbors or through drafting. Cetaceans, especially odontocetes, often swim in groups; nevertheless, the possibility that whales gain energetic benefits from swimming in formation remains poorly studied, apart from mother-calf pairs. Between June and September in 2019 and 2021, we recorded aerial videos of Southern Resident killer whales (Orcinus orca) in the Salish Sea (USA) travelling in groups. We estimated whale tailbeat and breathing frequencies as proxies of the relative energetic costs of swimming, and tested the effect of swimming speed, relative positioning (e.g., leaders, whales in the middle of groups, or followers), sex and estimated size on these observed proxies. Our results reveal a complex relationship between physical characteristics, relative positioning, and energetic proxies. Intervals between respiration lasted longer in large-sized trailing individuals, but the overall breathing frequency was similar for all whales regardless of their position. The tailbeat frequency was mainly associated to whale sex, size, and swimming speed; in addition, tailbeat frequency showed a decreasing trend as the number of individuals in the formation increased. We found moderate evidence that position-based energetic effects may be present in the formation swimming of killer whales, and it is likely that additional factors such as social ties and hierarchies, play a key role in determining individual positioning in travelling groups
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
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
Exploring the mechanisms and functions underpinning the social networks of an endangered population of killer whales, Orcinus orca
No full textFor the majority of social species, group composition is dynamic, and individuals are interconnected in a heterogeneous social network. In this study I investigate the mechanisms underpinning social structure in the endangered southern resident killer whale (Orcinus Orca) population using a long term dataset, and explore the consequences of these.
My results demonstrate that resource availability may be an important determinant of social network structure. A significant relationship between the connectivity of the social network and salmon abundance occurred, with a more interconnected network in years of high salmon abundance.
As networks are non-random, highly connected individuals may play a key role in population processes such as information and disease transmission. While associations occurred both within and between matrilines, females had a significantly higher number of associates than males, as did older individuals of both sexes. Older males played a more important role in interconnecting the network.
The attributes of group leadership were then investigated in matrilines and in individuals. Leadership was not a factor of size or mean age of matriline. However, there was a significant relationship between leadership score and the matriline sex ratio. Individually, females had higher leadership scores than males, and there was a positive correlation between leadership score and age in both sexes. I suggest that the oldest females have the highest
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leadership scores due to increased ecological knowledge that comes with a prolonged lifespan.
Using multi-generational records for two populations of killer whales, I show that both reproductive and post-reproductive mothers increase the survival of offspring, particularly in older male offspring. This is consistent with theoretical predictions, and may explain why female killer-whales have evolved the longest post-reproductive lifespan of all non-human animals.
Given the role that individuals of high network centrality can play in population processes, understanding the driving forces behind social network structure is vital when designing effective conservation and management plans.BBSR
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
Investigating the behaviour and welfare of captive flamingos (Phoenicopterformes)
Get PDFWhen a species is housed in captivity there are facets of the managed environment that can impact on individual and population welfare. A key component of an individual’s environment is its social environment, which can have important implications for animal health and welfare. Highly social species may experience impoverished welfare if kept in captive groups that differ in size, structure and demographic to that experienced by free-living animals. Amongst the most common of social animals to be housed in captivity are the flamingos (Phoenicopteridae). The unique evolutionary biology of these birds means that key aspects of their behaviour depends upon group living. A positive relationship between breeding success and increasing flock size has previously been noted, but how flamingo flocks are structured socially remains mysterious. All six species of flamingo are currently found in captive collections. The three more generalist species, greater (Phoenicopterus roseus), Caribbean (P. ruber) and Chilean (P. chilensis) flamingos are found commonly in zoos and can, under the right conditions, breed well. The other flamingo species are much more specialised in their habitat and dietary requirements and have proved more challenging with regards to their captive management. These three species are the Andean (Phoenicoparrus andinus), James’ (P. jamesi) and lesser (Phoeniconaias minor) flamingos. All six species are included in the experimental work presented in this thesis. This research aimed to evaluate specific elements of flamingo group living using social network analysis (SNA). It also aimed to assess influences of the captive environment (i.e. enclosure style and visitor number) and climate on enclosure usage, time-activity budgets and behavioural diversity to provide, as far as possible, a complete insight into how to measure, assess and evaluate captive flamingo welfare. A synthesis of the relevance of SNA to zoo animal management, and a review of current literature to identify research needs that could evidence good flamingo husbandry form the basis of the first two chapters. These two overview chapters support the questions asked in the following data-based sections of the thesis. Flamingos were observed at WWT Slimbridge Wetland Centre from March 2012 to July 2016 with data on patterns of social associations being collected four times daily (depending upon weather and bird husbandry). Associations were defined as birds within one neck length of each other and, using photos, the affiliations of each bird in the group were recorded. For assessment of bond strength, network position and identification of preferred/avoided partners a Half-Weight Index was applied to these data. Permutation testing was applied to association matrices to determine the difference between the number of observed preferential bonds (and avoided bonds) and Mantel tests were used to compare matrix correlations to assess differences between seasons, species, years and enclosures (where appropriate). The SNA programmes Socprog, UCInet and Netdraw were used to analyse network data. These network data form the basis of three chapters and show that flamingos associate preferentially with non-random bonds occurring in all flocks observed. Influences of social bonds on courtship display were also examined, and temporal changes in association were considered across time, season and year. Finally, to see any influence of animal health on bond preferences, scores of foot condition (used to identify and evaluate the presence and severity of pododermatitis on an individual bird) were analysed alongside of network measures for three flocks of flamingos. To measure enclosure usage, each species’ exhibit was measured and zones accessible to the birds were defined. As exhibit use can be based on resource use (and these resources can form differently-sized areas within an exhibit) a modified Spread of Participation Index (SPI) was used to provide an outcome between 1 (one area or resource used more than others) and 0 (equal use of all resource zones). Time-activity budgets were calculated for all flocks over daytime, and for one flock (measured using remote camera traps) over night. These data are presented in two chapters and demonstrate that captive flamingos can change their activity patterns in a similar manner to that noted in wild birds. Interestingly, flamingos are very active during the night and this provides useful data for zoo personnel to consider when re-assessing husbandry and management plans for these most ubiquitous of zoo birds
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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