bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the relationship between nurse influences over flexible working and commitment to nursing
Authors: Brooks Ian , Swailes Stephen
Published: March 2003

Analysis of the relationship between nurse influences over flexible working and commitment to nursing

Background. The paper explores the theoretical and practical bases of both commitment and control within the context of temporal aspects of flexible working in nursing.

Aim. The aims of the paper are to examine the relationships between nurses' shift patterns, influence over shift pattern and realization of shift preference and commitment to nursing.

Methods. Data were collected through a postal questionnaire completed by 2987 British nurses employed in hospitals, care homes and hospices. Principal components analysis was used to identify common factors among responses to a series of 33 statements about working life. Data were analysed using ANOVA and multiple regression techniques.

Results. Permanent night shift nurses reported lower levels of commitment to nursing. As predicted, influence over shift patterns and realization of preferred shift pattern were positively associated with commitment to nursing, although the relationship was weak. Positive perceptions of career development opportunities were a stronger predictor of commitment to nursing. Results are discussed in light of previous ethnographic research on nurses' shift patterns.

Conclusion. The opportunity to explore quantitatively the effects of shift‐related decisions on commitment using a large sample is useful. While influence and shift type were predictors of commitment, the positive impact they were expected to have was smaller than expected. Similarly, the negative effects of not having influence or of working permanent night shifts were smaller than expected and the statistical significance of such small effects relies heavily on the large sample obtained. Other variables, particularly career development prospects, outweigh the influence of shift‐related variables on commitment. The research gives a clear message to human resource managers involved with nurse management: so long as nurses have a strong perception of career development potential the otherwise negative influences of shift impact can be minimized.
Online learning: enhancing nurse education?
Authors: Kenny Amanda
Published: March 2003

Online learning: enhancing nurse education?

Aims of the study. The aim of this study was to explore the experiences of nursing students with `online' learning.

Background. The need to integrate information technology into nursing education has been recognized and well documented. In spite of this, information technology remains a neglected subject in many nursing programmes. Strategies have been considered for increasing the integration of information technology in nursing education. One of the key issues identified is the need for research into the factors that contribute to optimal learning with information technology, specifically the need to explore issues that contribute to student frustration and satisfaction with learning. Within Australia, the incorporation of information technology as a core subject in nursing education is still relatively new. This article describes how one university used `online' learning to expose students to conceptual and experiential opportunities that enabled them to develop skills in the management of information technology.

Methods. Twenty‐one students participated in this qualitative study. Individual interviews were used to develop insights into student perceptions. Thematic analysis enabled refined themes to emerge. These themes formed the basis of focus group discussions. Focus groups were used to enhance and validate the information from one‐to‐one interviews by using group dynamics to add experiential richness to the data.

Findings. Four major themes emerged: computer confidence, flexibility, active learning and practicalities of teaching.

Conclusions. The integration of information technology into nursing education requires a dramatic change in thinking. The `learning curve' is steep for both student and educator and there are many issues that need to be considered. This research does not aim to provide solutions to the issues highlighted but rather offers recommendations for enhancing the teaching and learning experience.
Deliberate self‐harm in adolescence: a systematic review of psychological and psychosocial factors
Authors: Webb Lucy
Published: March 2003

Deliberate self‐harm in adolescence: a systematic review of psychological and psychosocial factors

Aims. This paper is a systematic review of the research literature that identifies psychological and psychosocial factors associated with adolescent deliberate self‐harm (DSH). The aims of this review were to identify the key psychological and psychosocial factors that aid the identification of individuals at risk of DSH, and suggest specific strategies for intervention.

Background. Research has highlighted a parallel rise in rates of DSH referrals to general hospitals and rates of successful suicides in the younger age groups and gender groups. It is also highlighted that pressure on services in responding to these increases may be resulting in an inadequate response to both first‐episode DSH and repetition of self‐harm. One cause for concern is the lack of adequate psychosocial assessment for adolescents presenting at hospital following a DSH incident. Research of the literature suggests that there may be a paucity of research into after‐care strategies in self‐harm to prevent repetition and escalation of self‐destructive behaviour.

Methods. A systematic review of the literature was conducted to identify the psychological and psychosocial factors relating to DSH.

Results. The results found typical psychological and psychosocial factors associated with DSH in adolescents, although psychosocial factors were less consistently measured because of the breadth of tools and methods used.

Conclusions. It is discussed whether associated factors are causative of DSH or the accompanying symptoms in DSH. It is suggested that positive psychosocial factors may have a part to play in providing protection against DSH behaviour. Therapeutic responses to DSH are suggested as preventative measures against repeat episodes.
Power dressing and meta‐analysis: incorporating power analysis into meta‐analysis
Authors: Muncer Steven , Taylor Shirley , Craigie Mark
Published: March 2003

Power dressing and meta‐analysis: incorporating power analysis into meta‐analysis

Aims. This paper highlights the lack of consideration that is given to power in the health and social sciences, which is a continuing problem with both single study research and more importantly for meta‐analysis.

Background. The power of a study is the probability that it will lead to a statistically significant result. By ignoring power the single study researcher makes it difficult to get negative results published and therefore affects meta‐analysis through publication bias. Researchers using meta‐analysis, who also ignore power, then compound the problem by including studies with low power that are more likely to show significant effects.

Method. A simple means of calculating an easily understood measure of effect size from a contingency table is demonstrated in this paper. A computer programme for determining the power of a study is recommended and a method of reflecting the adequacy of the power of the studies in a meta‐analysis is suggested. An example of this calculation from a meta‐analytic study on intravenous magnesium, which produced inaccurate results, is provided.

Conclusion. It is demonstrated that incorporating power analysis into this meta‐analysis would have prevented misleading conclusions being reached. Some suggestions are made for changes in the protocol of meta‐analytic studies, which highlight the importance of power analysis.
The beliefs of nurses who were involved in a whistleblowing event
Authors: Ahern Kathryn , McDonald Sally
Published: March 2003

The beliefs of nurses who were involved in a whistleblowing event

Background. Nursing codes of ethics bind nurses to the role of patient advocate and compel them to take action when the rights or safety of a patient are jeopardized. Reporting misconduct is known as whistleblowing and studies indicate that there are personal and professional risks involved in blowing the whistle.

Aim. The aim of this study was to explore the beliefs of nurses who wrestled with this ethical dilemma.

Design. A descriptive survey design was used to examine the beliefs of nurses in Western Australia who reported misconduct (whistleblowers) and of those who did not report misconduct (nonwhistleblowers).

Methods. The instrument listed statements from current ethical codes, statements from traditional views on nursing and statements of beliefs related to the participant's whistleblowing experience. Respondents were asked to rate each item on a five‐point Likert format which ranged from strongly agree to strongly disagree. Data were analysed using a Pearson's correlation matrix and one‐wayANOVA. To further explore the data, a factor analysis was run with varimax rotation.

Results. Results indicated that whistleblowers supported the beliefs inherent in patient advocacy, while nonwhistleblowers retained a belief in the traditional role of nursing. Participants who reported misconduct (whistleblowers) supported the belief that nurses were primarily responsible to the patient and should protect a patient from incompetent or unethical people. Participants who did not report misconduct (nonwhistleblowers) supported the belief that nurses are obligated to follow a physician's order at all times and that nurses are equally responsible to the patient, the physician and the employer.

Conclusion. These findings indicate that nurses may respond to ethical dilemmas based on different belief systems.
Constructions of sexuality for women living with multiple sclerosis
Authors: Koch Tina , Kralik Debbie , Eastwood Sue
Published: March 2003

Aim.  In this paper we reveal constructions of sexuality that were articulated by 12 women who participated in an inquiry, which aimed to understand the experiences of women who live with multiple sclerosis (MS). The aim of this paper is to consider constructions of sexuality when chronic illness such as MS intervenes.

Background.  In previous studies women placed their sexuality on the agenda for discussion, claiming that their concerns had not previously been vocalized nor understood.

Design.  This participatory inquiry was framed by the principles of ‘look, think and act’. These principles are operationalized as looking at ourselves, reflecting and questioning aspects of our lives, and then taking action to resolve the issues identified. Twelve women aged between 30 and 60 years who lived with MS joined the three researchers for five group sessions. Each session lasted 3 hours. In addition, several women opted to be interviewed individually. In this paper we describe the way in which women have constructed and articulated their sexuality since acquiring MS.

Findings.  Sexuality has multiple meanings that are shaped and influenced by life experiences. When MS intrudes in a woman's life, sexuality is reshaped against a foundation of previous sexual experiences and expectations. Constructions of sexuality encompassed physical sexual responses, perceptions of appearance and attractiveness to self and others, communication and relationships, self‐image and self‐esteem, and the sense of affirmation and acknowledgement that women experienced from others in their everyday lives.

Conclusions.  This paper reveals that sexuality was not privileged by women but was regarded as an ordinary part of life. Often sexual activity was placed on hold as other aspects of living with a chronic illness intervene, for instance an exacerbation of MS. Whilst this paper has a focus on constructions of sexuality, there is a close relationship to shifts in self and identity. Health professionals need to reject the myths and stereotypes surrounding disabled women and attempt to understand the possible impact of long‐term illness on women's sexuality.
The lived experience of families of children who are failing to thrive
Authors: Thomlinson Elizabeth H.
Published: March 2003

Objective.  This study was conducted to explore the experience of families of children who were failing to thrive. The aim of the study was not to generalize the findings but to generate a rich description of the phenomenon of living with children who were not growing as expected.

Background.  Although failure to thrive has been found to have long‐term negative implications for children there is little information available on how families experience this phenomenon.

Methods.  A purposive sample of 12 families with children who were failing to thrive from multiple known and unknown reasons were interviewed (21 participants: mothers, fathers, and grandmothers).

Findings.  Twenty‐seven subthemes emerged from the descriptions provided by the participants and these were then grouped into seven themes. Families spoke of an all‐encompassing fear with which they lived. They were affected by the comparisons of the children made by others and themselves. In the process of seeking care for the children, the families described how their concerns often were not heard by the professionals. They felt blamed for their children's growth failure and this added to a sense of isolation and helplessness. Nurses and doctors who listened and acknowledged that they trusted the family were respected and valued. Families felt they were then valuable members of the care team. Regardless of the difficulties, families described how they adapted and persevered in their attempt to provide as normal a life as possible for the children. They considered themselves the experts who best knew the children and continued to provide the complex care that was needed.

Conclusions.  The research suggests that health care professionals need to be more aware of the impact of their words and actions on families.
Relieving discomforts: the help‐seeking experiences of Chinese perimenopausal women in Taiwan
Authors: Tsao Lee‐Ing
Published: March 2003

Background.  Although studies show that women view perimenopause as a natural process, few studies explore the experiences of Taiwanese mid‐life women who visit clinics for perimenopausal health problems. Research is required to understand the patterns and explanations for the women's behaviours in the process of seeking medical help. Such understanding will help guide teaching and care‐giving approaches.

Aims.  To generate a descriptive theoretical framework about the experiences of women who visited traditional Chinese and Western medicine clinics in Taiwan to seek medical help for perimenopausal symptoms.

Methods.  A grounded theory research design was used. Thirty Taiwanese women, aged 48–55 years, participated in two face‐to‐face audio‐taped interviews. Trained staff nurses conducted the interviews. Data collection, coding of interviews and field notes, and data analysis occurred simultaneously.

Findings.   ‘Relieving the discomforts’ was the core theme for describing and guiding the process of seeking medical help during the perimenopausal period. During the process, ‘Feeling the discomforts’ was identified as the antecedent condition. Analyses showed five dimensions to the women's help‐seeking behaviours: (1) searching for medical help, (2) taking medicine, (3) reassurance of health, (4) desiring to be understood, and (5) emotional swings.

Conclusions.  Women in this study expected to relieve their perimenopausal discomforts by finding treatment to match their body constitution. They hoped to find a caring and understanding doctor or staff member who would carefully explain health‐related issues to them. Health care providers need to consider women's individual health values and, based on these values, use different approaches to treat and teach women with perimenopausal symptoms and concerns.
Helpfulness of nursing actions to suddenly bereaved family members in an accident and emergency setting in Hong Kong
Authors: Li Serena P. , Chan Carmen W.H. , Lee Diana T.F.
Published: March 2003

Background.  The sudden death of a family member is always traumatic to the family. Nursing actions such as providing comfort measures and providing an opportunity to view the deceased were consistently perceived as helpful by the suddenly bereaved. Little is known about the perception of bereaved family members in Hong Kong concerning the care they received in accident and emergency (A & E) departments. This study serves to identify actions, which were perceived as helpful in A & E setting in Hong Kong.

Aim.  To gain knowledge about what nursing actions bereaved family members in Hong Kong perceived as helpful.

Method.  This study was exploratory and descriptive in nature, and used a quantitative approach. Data were collected through structured telephone interviews using a modified Tye's questionnaire.

Results.
 Seventy‐six bereaved subjects were recruited in an A & E department in Hong Kong. The subjects perceived written information, opportunity to view the deceased, and respecting individual customs and religious procedures as most helpful and conversely, offering sedation, discouraging viewing of the body, and providing comfort measures as most unhelpful. No statistically significant differences among the overall mean of helpful nursing actions according to the subjects' age, gender, education level, family income and religions were found while using Mann–Whitney's
U and Kruskal–Wallis' tests. Significant correlations between some actions and the respondents' age, family income and educational level were found.

Conclusion.  Accident and emergency nurses have unique role in offering helpful actions to support suddenly bereaved family members.
Cautious caregivers: gender stereotypes and the sexualization of men nurses' touch
Authors: Evans Joan A.
Published: March 2003

Aim. The aim of this research was to explore the experience of men nurses and the ways in which gender relations structure different work experiences for women and men in the same profession.

Background. Men are now entering the nursing profession in record numbers and challenging the notion that men are inappropriate in caregiver roles or incapable of providing compassionate and sensitive care. A limitation of the current state of knowledge regarding caring and men nurses is that it is primarily focused on men nursing students, not practising nurses. Little is known about men nurses' practices of caring and how such practices reflect the gendered nature of nursing and nurses' caring work.

Methods. The theme of men nurses as cautious caregivers emerged from data that were collected in two rounds of semi‐structured interviews with eight men nurses practising in Nova Scotia, Canada. Thematic analysis, informed by feminist theory and masculinity theory, was used as the method for analysing the data.

Findings. For men nurses, the stereotype of men as sexual aggressors is compounded by the stereotype that men nurses are gay. These stereotypes sexualize men nurses' touch and create complex and contradictory situations of acceptance, rejection and suspicion of men as nurturers and caregivers. They also situate men nurses in highly stigmatized roles in which they are subject to accusations of inappropriate behaviour. For men nurses, this situation is lived as a heightened sense of vulnerability and the continual need to be cautious while touching and caring for patients. Ultimately, this situation impacts on the ability of men nurses to do the caring work they came into nursing to do.
Knowledge, confidence and attitudes towards mental health of nurses working in NHS Direct and the effects of training
Authors: Payne Fiona , Harvey Kate , Jessopp Lynda , Plummer Sue , Tylee Andre , Gournay Kevin
Published: March 2003

Background.  NHS Direct, the United Kingdom's 24‐hour nurse‐led telephone advice service, was announced in December 1997. By November 2000 the service was available throughout England and Wales. Initial research had shown that people with mental health problems used the service and that, prior to its going live, this was one area about which nurses felt least confident.

Aims.  The aim of the study was to measure confidence in dealing with mental health calls, knowledge of mental health issues, and attitudes to mental health before and after training.

Methods.  A postal questionnaire was sent to all nurse advisers working in 17 NHS Direct sites in England before and after mental health training had been received. The questionnaire was designed to measure confidence, knowledge and attitudes. This was done through scenarios of real calls to NHS Direct, questions from the World Health Organization guide to Mental Health in Primary Care and the Depression Attitude Questionnaire.

Results.  Confidence increased in nurses who received mental health training. Although there was no statistically significant increase in knowledge scores after training, those who had received training increased by on average one point. After training, attitudes towards depression had shifted in that nurses now felt more positive towards their role in treating depressed patients.

Conclusions.  Training in mental health can lead to increases in confidence and a change in attitudes and would be beneficial for all nurses working in NHS Direct and in other primary care fields. It would also be beneficial to repeat the study with a larger number of nurses and after a longer period of time to assess the long‐term effects of training.
Methodological issues in male caregiver research: an integrative review of the literature
Authors: Houde Susan Crocker
Published: March 2003

Purpose of the paper. The purpose of this integrative review of the literature is to identify sampling and analysis issues related to gender in caregiver research in the nursing and health literature.

Background. Men provide approximately 28% of the care in the home to functionally impaired elders in the United States of America (USA), and because of demographic predictions are expected to provide more in the future. Social science research related to male caregivers has been criticized as having many limitations. A critical review of the nursing and health literature would be helpful to nursing researchers and clinicians by identifying limitations in caregiving research related to gender and providing direction for future research.

Methods. A literature search using the CINAHL database and the terms ‘family caregiver’, ‘dementia’, and ‘male’ was conducted. Thirty‐six articles were retrieved, reviewed, and abstracted.

Findings. Thirteen articles were qualitative studies, 22 were quantitative, and one had both qualitative and quantitative components. Many of the studies used small samples, and no analysis was included by gender. Most of the samples were convenience samples, with many being self‐selected. There was also a lack of analysis of data by family relationship. No qualitative studies and only nine of the quantitative studies included analysis of the data by gender. Studies that reported by gender were all cross‐sectional.

Conclusions. There is a need for caregiver research that has larger samples of males, and includes analysis by gender and family relationship. There is also a need for more intervention studies that are well controlled, and evaluate the effect of the intervention on both male and female caregivers.
Predictors of maternal competence by first‐time mothers when the child is 8 months old
Authors: Tarkka Marja‐Terttu
Published: March 2003

Background.  Maternal role attainment is largely a cognitive and social process that is influenced by the cultural and family context and the mother's and child's traits and characteristics. Feedback from a social network is important to validate competent performance.

Aim.  To ascertain factors that contributed to the maternal competence of first‐time mothers when the child was 8 months old.

Methods.  Data collection was by structured questionnaires. The sample consisted of 248 first‐time mothers who completed the questionnaires when their child was 8 months old. The data were analysed using stepwise regression analysis.

Results.  According to the multivariate analysis, nine predictors remained in the model to explain maternal competence. The more balanced the mother's state of mind, the better she felt about succeeding in child care, and the more easy going the child was, the greater was the mother's competence. The more the mother felt isolation from society, the less was her maternal competence. Younger and healthier mothers, and those who readily accepted their child showed better competence. Also, if the mother still breast‐fed her child, the more concrete support she received from the support network, the better was her maternal competence.

Conclusion.  The findings suggest important factors that contribute to the maternal competence of first‐time mothers include mothers' resources, ease of caring for the child, breast‐feeding and social support received from those close to them.
The Delphi technique: myths and realities
Authors: Powell Catherine
Published: March 2003

Aim. To outline the key concepts and principles of the Delphi technique.

Methods. Reference is made to a selection of studies that illustrate a variety of methodological interpretations. Drawing on Heshusius's concept of ‘goodness criteria’, particular emphasis is given to the question of scientific merit and means of evaluation.

Conclusion. Although the technique should be used with caution, it appears to be an established method of harnessing the opinions of an often diverse group of experts on practice‐related problems.
Host‐specificity of folivorous insects in a moist tropical forest
Authors: BARONE JOHN A.
Published: March 2003

1.  To assess the degree of herbivore host‐specificity in the moist tropical forest on Barro Colourado Island, Panama, I conducted an extensive series of feeding trials on the common insect herbivores from 10 tree species.

2.  The herbivores were offered leaves from both congeneric and confamilial plant species to their known host species, as well as leaves from the most abundant tree species in the forest.

3.  The amount of damage caused by these herbivores to young, expanding leaves was also measured on nine of the tree species.

4.  Of 46 herbivores species (seven Coleoptera, one Orthoptera, 38 Lepidoptera), 26% were specialized to a single plant species, 22% were limited to feeding on a single genus and 37% were able to feed on several genera within a single family. The remaining 15% were generalists, able to feed from several different plant families.

5.  The causes of leaf damage varied extensively across the tree species. On average, specialist herbivores caused 58% of the damage to young leaves, generalists herbivores 8% and fungal pathogens 34%. For four of the tree species, pathogens were the most important cause of leaf damage.

6.  In this forest, most chewing herbivores appear to have fairly narrow diets, and these specialists are responsible for most of the insect herbivory.
The form of the curves: a direct evaluation of MacArthur & Wilson's classic theory
Authors: Manne Lisa L. , Pimm Stuart L. , Diamond Jared M. , Reed Timothy M.
Published: March 2003

1. We calculate the yearly numbers of bird species immigrating to – and becoming extinct on – 13 small islands of the British Isles, using a long and relatively complete data record.

2. We estimate the size of the colonist pool for each island using four methods.

3. We assume that immigrations and extinctions are distributed binomially, and use a maximum likelihood method to fit concave immigration and extinction functions to the data, utilizing all four species pool estimates.

4. Extinction rates increase significantly and consistently with increasing numbers of breeding species on each island. For nine of the 13 islands the extinction functions are significantly concave.

5. Immigration rates decrease consistently with increasing numbers of breeding species on each island. Seven islands have significantly concave immigration functions.

6. Immigration rates and extinction rates decline consistently, but not significantly, with island distance and island size, respectively. The number of breeding species does not always reflect the number of species likely to have reached an island. Moreover, some species may choose not to breed when their chance of extinction is high. These factors, plus the modest range of island areas and distances in our database, reduce our chances of finding the theoretically predicted effects of area and distance on extinction and immigration rates.
Predator–prey relationships: arctic foxes and lemmings
Authors: Angerbjorn Anders , Tannerfeldt Magnus , Erlinge Sam
Published: March 2003

1. The number of breeding dens and litter sizes of arctic foxesAlopex lagopuswere recorded and the diet of the foxes was analysed during a ship‐based expedition to 17 sites along the Siberian north coast. At the same time the cyclic dynamics of co‐existing lemming species were examined.

2.The diet of arctic foxes was dominated by the Siberian lemmingLemmus sibiricus(on one site the Norwegian lemmingL. lemmus), followed by the collared lemmingDicrostonyx torquatus.

3.The examinedLemmus sibiricuspopulations were in different phases of the lemming cycle as determined by age profiles and population densities.

4.The numerical response of arctic foxes to varying densities ofLemmushad a time lag of 1 year, producing a pattern of limit cycles in lemming–arctic fox interactions. Arctic fox litter sizes showed no time lag, but a linear relation toLemmusdensities. We found no evidence for a numerical response to population density changes inDicrostonyx.

5.The functional or dietary response of arctic foxes followed a type II curve forLemmus, but a type III response curve forDicrostonyx.

6.Arctic foxes act as resident specialist forLemmusand may increase the amplitude and period of their population cycles. ForDicrostonyx, on the other hand, arctic foxes act as generalists which suggests a capacity to dampen oscillations.
Integrating nested spatial scales: implications for the coexistence of competitors on a patchy resource
Authors: Inouye Brian D.
Published: March 2003

1.Intraspecific aggregation at a single spatial scale can promote the coexistence of competitors. This paper demonstrates how this same mechanism can be applied to the many systems that are patchy at two scales, with patches nested within ‘superpatches’.

2.Data are presented from a field study showing that insects living in rotting fruits have aggregated distributions in the fruits under a single tree, and that the mean density and degree of aggregation varies significantly among trees. Observations in this system motivate the following models.

3.A model of competition has been developed between two species which explicitly represents spatial variation at two scales. By integrating the probability distributions for each scale, the marginal distributions of competitors over all patches can be found and used to calculate coexistence criteria. This model assumes global movement of the competitors.

4.Although spatial variation at a single scale may not be sufficient for coexistence, the total variation over all patches can allow coexistence. Variation in mean densities among superpatches and variation in the degree of aggregation among superpatches both promote coexistence, but act in different ways.

5.A second model of competition between two species is described which incorporates the effects of limited movement among superpatches. Limited movement among superpatches generally promotes coexistence, and also leads to correlations among aggregation and the mean densities of competitors.
Trade‐offs between nutrient intake and faecal avoidance in herbivore foraging decisions: the effect of animal parasitic status, level of feeding motivation and sward nitrogen content
Authors: Hutchings M. R. , Kyriazakis I. , Gordon I. J. , Jackson F.
Published: March 2003

1.Three experiments were carried out to determine whether a trade‐off between the benefit of increased nitrogen content of swards and risks of parasitism exists in a grazing situation for sheep (Ovis ariesL.). The effect of level of feeding motivation and parasitic status on the grazing behaviour of sheep faced with this trade‐off was also investigated. Animals were presented with pairs of experimental swards (36 × 21 cm), which varied in nitrogen content (high = N+; low = N−) and level of contamination with faeces from sheep infected withOstertagia circumcincta(Ostertag) (20 g faeces per sward = F+; no faeces = F−), and allowed to graze for short periods. For this study, a ‘high parasite risk’ grazing strategy is defined as taking more bites from an N+F+ sward compared to an N−F− sward, when presented together as the trade‐off choice.

2.Experiment 1 presented one choice (N+F− vs. N−F−) three times to 20 sheep divided into four animal treatment groups resulting from two levels of feeding motivation (high and moderate) and two parasitic states (parasitized byO. circumcinctaand non‐parasitized). Experiment 2 presented four choices (N+F+ vs. N−F− N+F+ vs. N−F+ ; N+F− vs. N−F− N+F− vs. N−F+) repeated three times to the same animals and treatments.

3.Experiment 3 presented the above four choices three times each to 24 sheep in four animal treatment groups created from two parasitic states (parasitized byO. circumcinctaand non‐parasitized) and two immune states (immune toO. circumcinctaand naive).

4.All animals selected the high nitrogen sward over the low nitrogen sward in experiment 1. When presented the trade‐off choice, animals with a high level of feeding motivation took greater parasitic risks, than moderately motivated animals in experiment 2. Both immune treatments took higher parasitic risks than both the naive treatments in experiment 3. Subclinical parasitism resulted in increased rejection of the N+F+ sward, reduced bite rates and grazing depths compared to non‐parasitized animals, thereby reducing further risk of parasitism in experiments 2 and 3. Non‐parasitized, moderately feeding motivated (control) animals in experiment 2 significantly rejected the N+F+ sward, adopting a low parasite risk strategy; non‐parasitized, naive (control) animals in experiment 3 adopted a similar grazing strategy. In each of the remaining three choices in both experiments one sward held a clear nitrogen or faecal benefit (absence of faeces) which was selected for by all treatments.

5.Sheep are able to make complex grazing decisions involving nutrition and faecal avoidance and these decisions are affected by their physiological state. However, faeces aversion in sheep greatly outweighs their attraction toward high nitrogen swards.
Flexible niche partitioning via a foraging mode shift: a proposed mechanism for coexistence in stream‐dwelling charrs
Authors: Nakano Shigeru , Fausch Kurt D. , Kitano Satoshi
Published: March 2003

1. Foraging behaviour, diet and interference competition were examined for two morphologically similar charrs,Salvelinus malma(Dolly Varden) andS. leucomaenis(white‐spotted charr), under varying food resource conditions over four summers in a Japanese mountain stream. Data were used to test predictions from a mechanistic model of resource partitioning developed from an earlier field experiment.

2. The charrs adopted one of two distinct foraging modes, ambushing drifting invertebrates from relatively fixed foraging positions or actively searching for benthic prey over large areas. The proportion of benthos foragers increased markedly when drifting prey declined, and was much greater inS. malmathanS. leucomaeniswhen drift was lean, upholding predictions made from our earlier experiment.

3. For drift foragers of both species, frequency of foraging attempts decreased as drift rate declined, and aggressive encounters increased. In contrast, for benthos foragers of both species the frequency of foraging attempts was essentially constant across the range of benthos biomass measured, and aggressive encounters remained low.

4. Salvelinus leucomaenisate larger drifting prey thanS. malma, even though the former charr were smaller. In contrast,S. malmaforaged on benthic prey at a higher rate thanS. leucomaenis, although there was no difference in prey mass. Thus, the optimal point to shift to benthic foraging is at a higher drift threshold forS. malmathanS. leucomaenis, most probably due to differences in jaw morphology. Moreover, because dominance for favourable drift foraging positions was based on size alone,S. malmashifted to benthos foraging at a larger size thanS. leucomaenis, as predicted by a simple model.

5. Charr consumed distinct prey types according to their foraging mode. Drift foragers primarily ate terrestrial invertebrates, whereas benthos foragers ate mainly chironomid larvae. Consequently, diet overlap was high when drift was abundant and both species were drift foragers, but declined as drift declined andS. malmashifted to benthos foraging. Therefore, species‐specific differences in foraging mode shifts across the resource gradient explained the flexible resource partitioning we observed, and probably account for the coexistence of these congeneric charrs in zones of sympatry in northern Japan.
The use of conspecific reproductive success for breeding habitat selection in a non‐colonial, hole‐nesting species, the collared flycatcher
Authors: Doligez Blandine , Danchin Etienne , Clobert Jean , Gustafsson Lars
Published: March 2003

1. Breeding habitat quality strongly affects fitness. Therefore, individuals are likely to select their breeding habitat after gathering information on quality of potential breeding patches. In the study reported in this paper, we investigated whether local reproductive success of conspecifics in a patch (patch reproductive success, PRS) could be used to assess habitat quality and make dispersal decisions in a non colonial, hole‐nesting, passerine bird, the collared flycatcher (Ficedula albicollis).

2. Assumptions for such a breeding habitat selection mechanism were met: the habitat patches were of different quality, as measured by PRS, with relative quality varying between years, and PRS was autocorrelated in time.

3. As in many other species, breeding dispersal was related in both sexes to individual reproductive success before dispersal: unsuccessful individuals were more likely to disperse than successful ones.

4. Additively, PRS influenced both breeding and natal dispersal. This effect depended on sex. Dispersal was negatively related to PRS in females, and positively in males with low competitive ability (juvenile and unsuccessful adult males).

5. Breeding dispersal was positively related to flycatcher density in males, but negatively in females. Moreover, when included in the analyses, laying date of the previous breeding attempt (which should be correlated with competitive ability) replaced the effect of PRS in adult males.

6. The observed patterns can be explained by PRS (or another variable correlated with PRS) being used to assess different components of habitat quality in each sex, in relation to intraspecific competition pressure. We suggest that males of low competitive ability may either use PRS to assess the level of expected intraspecific competition the following year, and choose to disperse from high PRS woodlands, or be forced to disperse when PRS is high because of strong competition. Females might use PRS to assess the expected reproductive output if breeding in the patch the following year.
Host diet affects extinctions and colonizations in a parasitoid metapopulation
Authors: Van Nouhuys Saskya , Hanski Ilkka
Published: March 2003

1. In the Åland islands of SW Finland, the parasitoidCotesia melitaearum(Wilkonson) is a specialist on the Glanville fritillary butterfly,Melitaea cinxia(L.),which uses two host plants,Plantago lanceolata(L.) andVeronica spicata(L.).

2. Extensive survey data on the butterfly and parasitoid populations collected in 1994–97 were used to examine possible associations of parasitoid colonizations and extinctions, with host population isolation, host population size, and host diet (plant species).

3. The likelihoods of parasitoid colonization and host patch occupancy were found to increase with decreasing isolation from other parasitoid populations, increasing host population size and an increasing fraction of host larvae onV. spicata. The likelihood of parasitoid population extinction increased with decreasing host population size and decreasing fraction of hosts onV. spicata.The pattern of association was exceptional in one area of high‐density parasitoid populations as well as during a year of many extinctions but few colonizations.

4. Among host populations occupied byC. melitaearum, the fraction of host larval groups parasitized was higher in host populations using the more rare host plant,V. spicata. If host larval groups were present on both host plant species within one host population, then the larval groups onV. spicatawere more likely to be parasitized.

5. The large‐scale population dynamics of the parasitoid wasp are influenced by the distribution of the two host plants of the butterfly, by host‐plant‐dependent parasitoid behaviour and by host butterfly oviposition preference.

6. Possible explanations for the apparent superiority ofV. spicataforC. melitaearumas the host butterfly's host plant are discussed. These include host larval group size, larval web structure, plant spatial aggregation, plant chemistry, and host larval physiology and phenology.
Predators, parasitoids and pathogens: species richness, trophic generality and body sizes in a natural food web
Authors: Memmott J. , Martinez N.D. , Cohen J.E.
Published: March 2003

1. A food web is presented which describes trophic interactions among the herbivores, parasitoids, predators and pathogens associated with broom, Cytisus scoparius (L.) Link. The data come from published work on the community at a single site. The web comprises a total of 154 taxa: one plant, 19 herbivores, 66 parasitoids, 60 predators, five omnivores and three pathogens. There are 370 trophic links between these taxa in the web. The taxa form 82 functionally distinct groups, called trophic species.

2. Predators consumed significantly more species than did parasitoids: a median of two prey species per species of predator (range = 1–9), compared to a median of one host species per species of parasitoid (range = 1–4). Significant differences in the number of species consumed were also found among the five predator groups: birds (median = 4), spiders (median = 5), Coleoptera (median = 1), Diptera (median = 2) and Hemiptera (median = 7).

3. Vulnerability, measured by numbers of consumer species, was significantly affected by the herbivores’ feeding styles: externally feeding herbivores were most vulnerable and the concealed herbivores were least vulnerable. Miners were vulnerable to the most parasitoid species and externally feeding herbivores were the most vulnerable to predators.

4. Resource species had a median vulnerability of 13 consumer species, a figure far higher than that in most published food webs. No significant relationship was found between species’ vulnerability to predators and vulnerability to parasitoids. However, there was a strong negative relationship between the percentage mortality due to predation and percentage mortality due to parasitism.

5. The broom food web contains nine orders of insects, a figure higher than previously recorded. The web also contains vertebrates, arachnids, bacteria and fungi. Most of the interactions between the orders were weak. Connectance was calculated for the complete web, the parasitoid sub‐web and the predator sub‐web. The connectance of the predator sub‐web, a value of 0·0364, was more than an order of magnitude larger than the connectance of the entire web (0·0156) or the parasitoid sub‐web (0·018).

6. The body lengths of 52 species in the food web were estimated from field guides or museum specimens. Larger predators consumed smaller prey in 93% of predator–prey interactions. Smaller parasitoids consumed larger hosts in 79% of parasitoid–host interactions. Parasitoids were significantly smaller than predators.

7. The 52 species were arranged in order of increasing body length along the columns and down the rows of a food web matrix. The predator sub‐web was predominantly upper triangular with 8% of non‐zero elements falling below the leading diagonal. The parasitoid sub‐web was predominantly lower triangular with 21% non‐zero elements falling above the leading diagonal. The entire web contains entries both above and below the main diagonal and thus violates a central assumption of the cascade model.
Sublethal infection and the population dynamics of host–microparasite interactions
Authors: Boots Michael , Norman Rachel
Published: March 2003

1. A large group of parasites, including many of the larval pathogens of insects, cause an infection from which infectious hosts are unable to recover. In addition, a proportion of those individuals that do not develop the lethal disease on exposure to the parasite may still be harmed by it.

2. We examined the role of these sublethal effects on host‐population dynamics. Specifically we considered the case where there are three distinct classes of individuals: (i) susceptibles; (ii) infected and infectious individuals that will not reproduce and cannot recover; and (iii) sublethally infected individuals.

3. Parasites with sublethal effects are less likely to persist and control their host population. This is a consequence of the sublethally infected individuals not being infective. Less intuitively, the sublethal infection is highly destabilizing, increasing the risk of cyclic behaviour in host–parasite population densities.

4. Because sublethal infection acts as a destabilizing force in these host–parasite interactions, parasites with pronounced sublethal effects may be less effective as classical biological control agents.
Intermittent breeding in the short‐tailed shearwaterPuffinus tenuirostris
Authors: Bradley J. S. , Wooller R. D. , Skira I. J.
Published: March 2003

1. At one colony of short‐tailed shearwaters in Bass Strait, Australia, all birds breeding have been recorded individually each year for over 50 years. Among individuals known to be alive and to have bred before, 14% of each sex were not present at their breeding colony, on average, in any one year.

2. A further 15% of males and 13% of females (a significant difference), known to have bred before, were present but not associated with an egg in any one year.

3. Intermittent breeding was associated with pair bond breakdown and with a reduced ability to raise offspring, even when years of absence were allowed for.

4. The frequency of attendance, laying and successful rearing of progeny to fledging increased with age in the early years of breeding. However, this was followed by a decrease, except in the case of laying frequency, which continued to increase throughout life.

5. Our analysis indicated that intermittent breeding in short‐tailed shearwaters did not result from individuals implementing trade‐offs between the effort required for breeding success and their breeding life span. Rather, we suggest that individuals of higher quality are able to breed more frequently than others without any compensatory reduction in either their annual breeding success or their overall breeding life span.