Testing the effect of conspecific reproductive success on dispersal and recruitment decisions in a colonial bird: Design issues

Factors affecting dispersal and recruitment in animal populations will play a prominent role in the dynamics of populations. This is particularly the case for subdivided populations where the dispersal of individuals among patches may lead to local extinction and 'rescue effects'. A long-term observational study carried out in Brittany, France, and involving colour-ringed Black-legged Kittiwakes (Rissa tridactyla) suggested that the reproductive success of conspecifics (or some social correlate) could be one important factor likely to affect dispersal and recruitment. By dispersing from patches where the local reproductive success was low and recruiting to patches where the local reproductive success was high, individual birds could track spatio-temporal variations in the quality of breeding patches (the quality of breeding patches can be affected by different factors, such as food availability, the presence of predators or ectoparasites, which can vary in space and time at different scales). Such an observational study may nevertheless have confounded the role of conspecific reproductive success with the effect of a correlated factor (e.g. the local activities of a predator). In other words, individuals may have been influenced directly by the factor responsible for the low local reproductive success or indirectly by the low success of their neighbours. Thus, an experimental approach was needed to address this question. Estimates of demographic parameters (other than reproductive success) and studies of the response of marked individuals to changes in their environment usually face problems associated with variability in the probability of detecting individuals and with nonindependence among events occurring on a local scale. Further, very few studies on dispersal have attempted to address the causal nature of relationships by experimentally manipulating factors. Here we present an experiment designed to test for an effect of local reproductive success of conspecifics on behavioural decisions of individuals regarding dispersal and recruitment. The experiment was carried out on Kittiwakes within a large seabird colony in northern Norway. It involved (i) the colour banding of several hundreds of birds; (ii) the manipulation (increase/decrease) of the local reproductive success of breeding groups on cliffpatches; and (iii) the detailed survey of attendance and activities of birds on these patches. It also involved the manipulation of the nest content of marked individuals breeding within these patches (individuals failing at the egg stage were expected to respond in terms of dispersal to the success of their neighbours). This allowed us to test whether a lower local reproductive success would lower (1) the attendance of breeders at the end of the breeding season; (2) the presence of prospecting birds; and (3) the proportion of failed breeders that came back to breed on the same patch the year after. In this paper, we discuss how we dealt with (I) the use of return rates to infer differences in dispersal rates; (II) the trade-off between sample sizes and local treatment levels; and (III) potential differences in detection probabilities among locations. We also present some results to illustrate the design and implementation of the experiment.     

'Your friends don't understand': Invisibility and unmet need in the lives of 'young carers'

This paper is based on a study of the experiences of people identified as ‘young carers’, commissioned by the National Assembly for Wales as part of a wider review of carers’ needs and services. Following a brief review of some of the previous research in this area, the paper reports key findings of the research, using the words of children and young people as much as possible. It then goes on to explore some of the wider implications of this and other research for the identification and support of ‘young carers’ and their families, and for the understanding of the needs and wishes of children and young people so defined. The paper concludes with an alternative definition of a ‘young carer’ and with some recommendations for professional practice, suggesting that the role of social work is crucial in this area of service.     

Productivism is allegedly dead, long live productivism. Evidence of continued productivist attitudes and decision-making in South-East England

The adjustment of the European Union's Common Agricultural Policy (CAP) initiated in the mid-1980s in response to its high cost and in-built tendency for overproduction set in train a series of measures that have been interpreted as reversing the former emphasis on agricultural production and diverting farmers towards alternative approaches to running their businesses. The policy reform measures have been characterised as contributing to a structural transition from a ‘productivist’ to ‘post-productivist’ era in agriculture, although empirical evidence for such reorientation at the farm level is less than conclusive. This paper reports on results from an analysis of large-scale commercial farmers in an area of relatively intensive arable and mixed livestock farming using documentary and survey sources to seek evidence of this transition over the long-term. Although these farmers have engaged with policy reform measures where these do not conflict with their primary objective, they continue to intensify and specialise their agricultural operations and to concentrate productive farm resources through accumulation and expansion.     

Effects of exercise training with weighted vests on bone turnover and isokinetic strength in postmenopausal women

The effects of 12 wk of exercise training using weighted vests on bone turnover and isokinetic strength were evaluated in postmenopausal women randomly assigned as exercisers (EX; n = 9) or controls (CON; n = 7). Training included 3 multimodal exercise sessions per wk wearing weighted vests. The vest load was progressively increased each wk to a maximum of 15% of body weight. Bone turnover was determined from resting levels of serum osteocalcin and NTx. Knee and ankle strength were measured at 60 degrees/s and 180 degrees/s using an isokinetic dynamometer. After 12 wk, NTx decreased by 14.5% (P 相似文献   

Five artists' valuations of the visual

Abstract

This paper comprises interviews with five practising artists: Terry Atkinson, Torie Begg, Rebecca Fortnum, Lubaina Himid, and James Hugonin. The aim is to gauge the ways in which ‘the visual’ features in contemporary fine art practice, not only at the end of a century in which the visual ‐ at least for much of the first half of that century ‐ was often accorded special status, but also, more recently, after Conceptualism and radical egalitarian interventions have challenged the status of and assumptions about the value of the visual. All five artists were asked the same questions: What/who are the formative influences on your work?; What role does the visual play in your work ‐ to what extent do you value the visual?; Can you say something about (i) aesthetic and (ii) pleasure ‐ however you define them?; How does a work evolve?; How do you define quality ‐ what makes you think one of your works is better than another?; What is the spectator's relationship to your work? ‐ what role does the spectator have? The responses bear witness to significantly different ways in which contemporary artists value the visual.     

Anti‐semitism and the Jewish community of Newcastle‐upon‐Tyne

After briefly outlining the historical development of the Jewish community in Newcastle‐upon‐Tyne, this article examines the extent to which anti‐Semitism was a major concern in the life of modern North‐East Jewry. The focus of this discussion is on the 1930s and 1940s, a period when anti‐Semitism assumed greater significance. What this artcle revals is that on Tyneside, even though the fear of anti‐Semitism gave rise to active responses from within the local Jewish community, anti‐Semitism remained small scale. The experience of Newcastle's Jewish community should caution us against overstating the prevalence of anti‐Semitism in British society.     

Endorsement of Criminal Behavior Amongst Offenders: Implications for DSM-5 Gambling Disorder

The fifth edition of the diagnostic and statistical manual (DSM) has changed the scoring threshold for a gambling disorder (GD) from five criteria to four and eliminated the illegal acts criterion. The impact of these changes was examined with data from a correctional population (N = 676) in Ontario, Canada. The offenders completed a self-report survey that included the Canadian problem gambling index, the South Oaks Gambling Screen and the DSM-IV criteria. Changing the threshold from 5 to 4 improved the convergent validity for GD and resulted in an increase in the percentage of offenders diagnosed with a GD from 7.4 to 10.2 %. The results also indicate that the illegal acts criterion contributes to the convergent validity of GD. The evidence supports the change in the threshold from five to four, but also reinforces the importance of examining illegal acts when dealing with an offender population. The incorporation of illegal acts into the “lying to others” criteria appears to make up, to some extent, for the removal of the illegal acts criterion.     

Most valuable stakeholders: The impact of employee orientation on corporate financial performance

In sports, the most valuable player award goes to the individual or group of players who have contributed most to the success of the team. This paper presents the results of two Australian empirical studies conducted six years apart, which suggest that, in business, employees are the most valuable stakeholder group. In particular, we find evidence to support the proposition that employee orientation contributes more to corporate financial performance (CFP) than orientation towards any other individual primary stakeholder group, including customers, communities, suppliers and shareholders. These findings have practical implications for corporate level strategy and the prioritization of budgetary resources by communication managers. From a theoretical perspective, the paper contributes to the debate on the best way to conceptualize employee orientation.