bluuebunny/crossref_metadata_2025 huggingface dataset:
Do Not Resuscitate orders and older patients: findings from an ethnographic study of hospital wards for older people
Authors: Costello John
Published: March 2003

Background and aim.  This paper reports on the findings from an ethnographic study involving three wards in two hospitals in the Northwest of England and focuses on the controversial issue of Do Not Resuscitate (DNR) orders. The study aimed to explore the way in which terminal care was provided to older patients and examined the way in which DNR orders were a socially constructed part of the practices of both nurses and doctors.

Method.  An ethnographic approach was adopted that used participant observation and semi‐structured interviews with nurses and doctors. A purposive sample of 28 qualified nurses and five medical staff were interviewed. The decision‐making process of DNR orders became the focus of the interview questions.

Findings.  The findings reveal that DNR decision‐making was largely socially constructed from the interactions of hospital staff. Patients were not asked their preference and were excluded from any decision‐making about Cardiopulmonary Resuscitation (CPR) or DNR orders. Two major findings emerge. First, DNR orders and the non‐use of CPR could be seen as a form of medical beneficence, resulting from the often described paternalistic attitudes of hospital doctors. Second, there was a clear indication that DNR orders and the non‐use of CPR for certain patients was based on improving the quality of patients' lives.

Conclusion.  The study raises issues about the quality of care received by frail older patients whom the nurses felt would not survive a futile medical procedure. The conclusion considers the need for hospitals to formulate and implement CPR policies, particularly in the prevailing climate in which patients are encouraged to become active participants in their own health care.
Nursing home employment for nursing students: valuable experience or a harsh deterrent?
Authors: Happell Brenda
Published: March 2003

Aim of the study.  The primary aim of the study was to examine the attitudes of undergraduate nursing students at the both the beginning and end of their nursing course.

Background.  Throughout Australia there is increasing awareness of the ageing of the population and the widespread implications this will have for the future. The ramifications for the health system are expected to be wide and far‐reaching. For the nursing profession the increase in the number of aged people will increase the demand for nurses to practice within the aged care area. This raises serious concerns in light of the negative attitudes that Registered Nurses and undergraduate nursing students hold towards working with older people.

Methods.

 This paper reports the results of a longitudinal study of undergraduate nursing students at the start (
n

 = 793) and at the end (
n  = 524) of their nursing education programme.

Findings.  The findings support the literature in demonstrating that working with older people is the least preferred area of practice for students, and that its popularity actually declines during the education process. One interesting finding from this research suggests that part‐time employment of student nurses in nursing homes can further influence students' negative attitudes.

Conclusions.  If nursing students are to continue working in aged care, strategies to address the potential detrimental impact need to be identified and developed as a matter of urgency.
The educational preparation of undergraduate nursing students in pharmacology: a survey of lecturers' perceptions and experiences
Authors: Bullock Shane , Manias Elizabeth
Published: March 2003

Background.  Nurses have key responsibilities in the administration and management of medication therapy and client education. It is of some concern therefore that the literature indicates that nurses are inadequately prepared in this area.

Aims.  This paper explores the perceptions and expectations of lecturers about teaching and learning pharmacology in preregistration nursing courses.

Research methods.

 Questionnaires were distributed to lecturers involved in teaching pharmacology to undergraduate nursing students during 2000. The questionnaire was distributed to all university campuses (
n  = 13) in Victoria, Australia, that are involved in undergraduate nursing education. The questionnaire was an adaptation of the survey instrument used in the Nursing and Medication Education [NAME] project and examined in this questionnaire: the integration of pharmacology teaching into nursing, range and depth of classroom‐based pharmacology teaching, approaches to teaching and learning, nursing practice in a clinical context, related importance of patient education and communication skills, and the appropriate professional background of academics teaching pharmacology to preregistration nursing students.

Results.  There was great variation between institutions as to the number of hours devoted to pharmacology and when it was offered. A number of respondents indicated that they were dissatisfied with the preparation of graduates and their knowledge base in pharmacology.

Limitations.  The study was limited by a low response rate of 34%.

Conclusions.  A review of nursing curricula is required to improve the knowledgebase of nurses in pharmacology and to facilitate their skills in life‐long learning.
Ethical review of health service research in the UK: implications for nursing
Authors: Tod A.M. , Nicolson P. , Allmark P.
Published: March 2003

Background.  This paper examines the current systems and structures for ethical review of health services research in the United Kingdom (UK). Past criticisms and the adequacy of recent governance arrangements for Ethics Committees in addressing these are discussed. The implications for nurses are then considered.

Rationale.  This examination of the situation is prompted by the demand for more innovative research designs in health care evaluation, new regulations and guidance, and a climate of public anxiety regarding research conduct in the UK.

Findings.  The evolution of Research Ethics Committees (RECs) has been slow and resulted in a lack in consistency. Criticisms made of RECs can be categorized into four main areas. New governance arrangements for RECs have emerged as potential solutions to these criticisms. This review identifies the limitations of the new governance arrangements in addressing past criticisms because of two factors. The first is insufficient funding. The second is confusion about the confidentiality and consent requirements of clinicians working in areas where research is conducted and on whom recruitment processes often rely. The current situation regarding health research ethical review has implications for nurses, whether they are working as researchers, members of Ethics Committees or clinicians where research is conducted.

Conclusion.  The new governance arrangements may go some way to addressing past problems. However, investment in RECs is required. It is also important to realize that maintaining ethical probity in health service research is a tripartite concern. It is reliant as it is on the actions of Ethics Committees and clinical research partners as well as those of the researchers themselves.
User‐friendly technology to help family carers cope
Authors: Chambers Mary , Connor Samantha L.
Published: March 2003

Background.  Increases in the older adult population are occurring simultaneously with a growth in new technology. Modern technology presents an opportunity to enhance the quality of life and independence of older people and their family carers through communication and access to health care information.

Aim.  To evaluate the usability of a multimedia software application designed to provide family carers of the elderly or disabled with information, advice and psychological support to increase their coping capacity.

Intervention.  The interactive application consisted of an information‐based package that provided carers with advice on the promotion of psychological health, including relaxation and other coping strategies. The software application also included a carer self‐assessment instrument, designed to provide both family and professional carers with information to assess how family carers were coping with their care‐giving role.

Design.  Usability evaluation was carried out in two stages. In the first stage (verification), user trials and an evaluation questionnaire were used to refine and develop the content and usability of the multimedia software application. In the second (demonstration), stage evaluation questionnaires were used to appraise the usability of the modified software application.

Findings.  The findings evidenced that the majority of users found the software to be usable and informative. Some areas were highlighted for improvement in the navigation of the software.

Conclusions.  The authors conclude that with further refinement, the software application has the potential to offer information and support to those who are caring for the elderly and disabled at home.
The art of developmental care in the NICU: a concept analysis
Authors: Aita Marilyn , Snider Laurie
Published: March 2003

Introduction.  The survival rate of infants born prematurely and hospitalized in Neonatal Intensive Care Units (NICUs) has increased due to improvement of the technology in obstetrics and neona tology that allows saving preterm infants at earlier gestational ages. Preterm infants are hospitalized in a care environment which is quite different from the maternal womb. Therefore the application of developmental care in NICUs is critical to promote the development of preterm infants while they are hospitalized.

Aim.  This concept analysis contributes to the body of knowledge in developmental care and clarifies its understanding as well as its involvement in neonatal practice and research.

Methods.
 Using the method of concept analysis of Walker and Avant, this article identifies the definitions and uses of the concept of developmental care, exposes its main attributes and introduces a model case representing the acknowledged attributes. The antecedents of the concept and consequences of the application of developmental care are discussed.

Conclusion.  This concept analysis provides guidelines for nurses and health professionals to establish a ‘developmental care’ environment which is conducive for preterm infants. Moreover, it suggests conceptual and operational foundations of developmental care for clinicians and researchers in the neonatal field.
Parents' use of nonpharmacological methods to alleviate children's postoperative pain at home
Authors: Kankkunen Päivi , Vehviläinen‐Julkunen Katri , Pietilä Anna‐Maija , Halonen Pirjo
Published: March 2003

Study background. Nonpharmacological methods are stated to be effective in alleviating children's postoperative pain when used as an adjuvant to analgesics. However, little is known about how these methods are used by parents at home.

Purpose of the study. The purpose of this study was to describe parents' use of nonpharmacological methods at home in 1–6‐year‐old children's pain alleviation after minor day surgery.

Methods. Mothers (n  = 201) and fathers (n  = 114) whose child had undergone day surgery in 10 Finnish hospitals between October 2000 and September 2001 filled in a questionnaire including a Visual Analogue Scale, Parents' Postoperative Pain Measure and a subscale consisting of 25 items measuring parents' use of several nonpharmacological pain alleviation methods with their children at home after day surgery.

Results. The most frequently used nonpharmacological pain alleviation methods were holding the child on the parent's lap, comforting the child and spending more time with them. Differences were found in mothers' and fathers' use of these methods. In addition, several methods were used more with girls than with boys. Significant relationships were found between parents' use of nonpharmacological pain alleviation methods and children's pain intensity and pain behaviour.

Conclusions. Parents used several nonpharmacological pain alleviation methods with their children. However, their implementation seemed to be gender‐related and limited to methods that were familiar to the parents from everyday life. The findings can be used in advising parents to use nonpharmacological pain alleviation methods at home after surgical procedures. Further research using experimental designs is needed into the effectiveness of these methods.
Identifying key factors using λ contribution analysis
Authors: Sibly Richard M. , Smith Robert H.
Published: March 2003

1.  Key factor analysis is widely used as the first step in analysing census data to identify factors responsible for population change, but is generally considered to be flawed. The conceptual problems can be overcome by assessing the effects of variation in the life‐history parameters on population growth rate, λ. We refer to this as λ‐contribution analysis. The difference from key factor analysis is that now each life history parameter is weighted by the sensitivity of λ to that parameter. The rationale for this modification is that population growth rate is the best available measure of population change.

2.  The advantages of the new method are: that it correctly assesses the effects of life history parameters on population growth rate; that birth rates are included in the analysis in a natural way without making arbitrary assumptions about birth rate mortalities; that post‐reproductive individuals who do not contribute to population growth rate are zero‐weighted; and that the analysis can be applied to populations with overlapping generations.

3.  It is proposed that λ‐contribution analysis should replace conventional key‐factor analysis as the first step in a wider analysis of population change and density dependence. λ‐contribution analysis also links census studies of natural populations with the use of life‐table response experiments.
Variable mating patterns in Tasmanian native hens (Gallinula mortierii): correlates of reproductive success
Authors: Goldizen Anne W. , Putland David A. , Goldizen Alan R.
Published: March 2003

1.  The Tasmanian native hen (Gallinula mortierii) exhibits mate‐sharing by both males and females, with monogamy, polyandry, polygyny and polygynandry all occurring in a single population.

2.  Multivariate models are used to investigate the relationships between reproductive success and a number of aspects of group compositions and territories in a population of Tasmanian native hens studied at Maria Island, Tasmania, Australia, over five breeding seasons.

3.  Mating pattern did not remain a significant explanatory variable in most of the models of the factors affecting reproductive success, suggesting that the reproductive success of individuals is not affected by their mating pattern. The only exception was that mating pattern was significantly related to clutch size, because co‐breeding females laid combined clutches.

4.  Breeding success (per group, per breeding male and per breeding female) was most significantly related to the total length of edge between short pasture and tall, dense vegetative cover present in a territory. It is proposed that edges between short pasture and cover allow the Tasmanian native hens’ precocious chicks to be near good feeding areas while also remaining close to protective cover.

5.  Individual components of breeding success were most significantly related to different variables. The presence of water in the territory increased the probability that a group laid eggs. Clutch size was most affected by a group’s mating pattern. Hatching success increased with the number of adults in a group. Chick survival increased with the length of pasture/cover edge in a group’s territory.

6.  The probability that mate‐sharing by males occurred in a group was positively related to the total length of pasture/cover edge in the group’s territory. There was no such relationship for mate‐sharing by females.

7.  These models suggest that individuals do not incur any net costs from sharing mates and that such sharing may allow some individuals to breed in higher‐quality territories than those to which they would otherwise have access.
Fitness correlates of spur length and spur asymmetry in male wild turkeys
Authors: BADYAEV ALEXANDER V. , ETGES WILLIAM J. , FAUST JOHN D. , MARTIN THOMAS E.
Published: March 2003

Tarsal spurs play an important role in intrasexual competition for females among male wild turkeys (Meleagris gallopavo). Thus variation in spur development may have important fitness consequences.

Fitness correlates of spur development were studied in a free‐living population of wild turkeys and it was found that heavier males and males with longer beards had longer spurs. Males that had longer spurs spent more time on display areas during the breeding season and less time moving among these areas compared to males with shorter spurs, independently of their body mass.

Otherwise ideally symmetrical spurs showed fluctuating asymmetry between left and right tarsi, the degree of absolute asymmetry decreased with spur length in adults, but not in subadults, and males that survived at least one winter had more symmetrical spurs compared to males that did not.

We conclude that if the ability to produce symmetrical spurs has a genetic basis, then spur length and spur asymmetry could reliably indicate individual quality and that these traits are under directional selection for increased size and symmetry in wild turkeys.
Cats protecting birds: modelling the mesopredator release effect
Authors: Courchamp Franck , Langlais Michel , Sugihara George
Published: March 2003

1.Introduced predators account for a large part of the extinction of endemic insular species, which constitutes a major component of the loss of biodiversity among vertebrates. Eradication of alien predators from these ecosystems is often considered the best solution.

2.In some ecosystems, however, it can generate a greater threat for endemic prey through what is called the ‘mesopredator release’. This process predicts that, once superpredators are suppressed, a burst of mesopredators may follow which leads their shared prey to extinction.

3.This process is studied through a mathematical model describing a three species system (prey–mesopredator–superpredator). Analysis of the model, with and without control of meso‐ and superpredators, shows that this process does indeed exist and can drive shared prey to rapid extinction.

4.This work emphasizes that, although counter‐intuitive, eradication of introduced superpredators, such as feral domestic cats, is not always the best solution to protect endemic prey when introduced mesopredators, such as rats, are also present.
Small‐scale spatial dynamics in a fluctuating ungulate population
Authors: Coulson Tim , Albon Steve , Pilkington Jill , Clutton‐Brock Tim
Published: March 2003

1.The scale at which population dynamics are analysed is important, as results from analyses at different spatial scales can differ and affect interpretation.

2.In this study, detailed census data collected over a 10‐year period from a population of Soay sheep (Ovis ariesL.) on the Island of Hirta in the St Kilda archipelago, Scotland, is used, together with cluster analysis, to distinguish a temporally stable spatial substructure.

3.Structured demographic accounting of the variance in population change (SDA) is also used to analyse the dynamics of the whole population treated as (a) one unit; (b) one unit subdivided into three subunits; and (c) three independent units.

4.Differences in survival, recruitment and dispersal rates are demonstrated between divisions of the population, which are probably associated with variation in grazing quality.

5.If these groups were not coupled by dispersal and density‐independent entrainment, the population dynamics of the three groups would diverge, however, the dynamics of the three subunits are strongly correlated.
Repeated selection of morphometric traits in the Soay sheep on St Kilda
Authors: Milner J. M. , Albon S. D. , Illius A. W. , Pemberton J. M. , Clutton‐Brock T. H.
Published: March 2003

1. Long‐term studies allow the outcomes of repeated selection events to be monitored. Here, we investigate phenotypic selection in successive winter mortality events in the Soay sheep of St Kilda, Scotland, between 1985 and 1996. Selection of three quantitative morphometric traits, body weight, hindleg length and incisor arcade breadth, was investigated in different sectors of the population.

2. Evidence from fitness differentials of positive directional selection for large size was repeatedly found in lambs and adult females. Selection in the opposing direction was only found in one year in lambs.

3. Selection gradients showed that in most years when significant selection occurred, body weight was the focus of direct selection, whereas selection of hindleg length and incisor breadth was indirect, arising from their correlation with body weight.

4. Selection was strongest in years of low over‐winter survival and almost absent in years when survival was high. Intensity of selection was greatest in lambs, emphasizing the differences in selection pressure experienced by different sectors of the population, in addition to the temporal variation in selection pressure due to population density and environmental conditions.

5. Despite repeated positive selection of body weight, no evidence of a change in the population mean was found over the course of the study.
Snowshoe hare demography during a cyclic population low
Authors: Hodges K. E. , Krebs C. J. , Sinclair A. R. E.
Published: March 2003

1.Snowshoe hare (Lepus americanusErxleben) populations were studied in south‐west Yukon during the low phase of the 10‐year population cycle. Food availability and predator abundance were manipulated in a factorial design to determine the importance of each factor in hare dynamics during this phase.

2.Food was abundant during the low phase, and snowshoe hares were not food limited.

3.Survival of hares was higher than at any other phase of the cycle, and predators were scarce, but >75% of hare deaths resulted from predation.

4.Food addition resulted in higher hare densities and better body condition than on control sites. There were no observable effects of food addition on population rate of increase, recruitment, survival or age structure.

5.Mammalian predator reduction resulted in higher hare densities, higher survival, better body condition and an older age structure. Relative to control populations, recruitment was lower and population rates of increase similar.

6.The joint manipulation of food addition + predator reduction had greater positive effects on hare density and body condition than either single factor manipulation. Survival was better than on control sites, and the age structure was older than on control sites. Population rates of increase were similar, but recruitment was higher on the control areas.

7.We conclude that snowshoe hare dynamics at the low of the cycle are dominated by the interaction of food and predation. Risk of predation also had indirect effects on snowshoe hare age structure and body condition.
Gyrfalcon predation on ptarmigan: numerical and functional responses
Authors: Nielsen Ólafur K.
Published: March 2003

1. Gyrfalcon predation on ptarmigan during the breeding season was studied in north‐east Iceland 1981–97. The ptarmigan population went through a complete 10‐year cycle of numbers with a 4·3‐fold difference in density between high and low years. The yearly number of occupied gyrfalcon territories was correlated with ptarmigan density with a 3‐year time‐lag. Total falcon numbers in late summer (territorial adults + fledglings) showed a 2‐year lag with ptarmigan numbers. Variability in falcon density was significantly less than that of ptarmigan. It is suggested that the factors contributing to the time‐lag between the two populations are the year‐round residency of falcons on nesting territories, and late maturity (2‐ to 4‐year‐old). Mean brood size and the proportion of the territorial falcon population breeding successfully showed no relation to ptarmigan numbers.

2. Ptarmigan density in spring was an important factor determining composition and variability in the diet of gyrfalcons during the breeding season. Alternative prey for falcons included waterfowl, alcids and waders. Adult ptarmigan featured highly in gyrfalcon diet in all years. The functional response curve to changes in ptarmigan density was slightly convex or close to linear and showed relatively little change in the average number of ptarmigan killed per individual predator over the range of ptarmigan densities observed.

3. The impact of gyrfalcon predation on the ptarmigan population and ptarmigan density was in opposite phases, and the predation rate peaked during the decline and the low phase of the ptarmigan cycle. This suggests that gyrfalcons accelerate decline, accentuate the amplitude and affect the length of the low phase of the ptarmigan cycle. The following factors seem to promote the destabilizing effects of predation by gyrfalcons: they are resident specialist predators, they show a delayed numerical response to changes in ptarmigan density and a high utilization of this prey at all phases of the ptarmigan cycle.
The effect of dispersal on the population dynamics of a gall‐forming midge and its parasitoids
Authors: Briggs Cheryl J. , Latto John
Published: March 2003

1. Theoretical studies predict that limited amounts of dispersal of individuals in host‐parasitoid systems can both enhance the stability of the subpopulations and promote the co‐existence of competing parasitoid species. We investigated the effects of dispersal on the population dynamics and parasitoid community structure of a natural host‐multi‐parasitoid system consisting of the midge Rhopalomyia californica that forms galls on the shrub Baccharis pilularis and the parasitoids that attack the midge.

2. An experiment involving the release of midges into a field with a low background density of galls demonstrated that the midges, on average, travelled approximately 1·7m in their lifetime. This suggests that the appropriate spatial scale at which to look at the effects of dispersal is relatively small.

3. Dispersal of midges and parasitoids between individual bushes was experimentally eliminated in a caging experiment. The midge populations in all of the uncaged replicates displayed dynamics that were similar to each other, while the dynamics of the midge populations in the caged replicates diverged. The midge dynamics on the uncaged bushes were not significantly more stable than those on the caged bushes.

4. Dispersal among bushes was found to play a major role in co‐existence of the competing parasitoid species. There was a dramatic drop in the parasitoid species diversity on the caged bushes, with only a single parasitoid species, Platygaster californica, persisting at high numbers in the caged populations. In accordance with theoretical models, P. californica is the parasitoid species in the community that has the highest attack rate and is most effective at searching for hosts in a restricted area. Alternative explanations for this pattern are discussed.
State‐dependent behaviour and energy expenditure: an experimental study of European robins on winter territories
Authors: Godfrey J. D. , Bryant D. M.
Published: March 2003

1. We sought evidence for state‐dependent behaviour and energy expenditure by manipulating the body‐state of birds. We reviewed three hypotheses that could describe responses to a change in body‐state: the Increased Effort; Reduced Effort; and Balanced Effort Hypotheses.

2. Territorial European robins Erithacus rubecula L. were captured at dusk during winter, and chilled or warmed overnight to manipulate body‐state.

3. The robins were released onto their territories before dawn. Their subsequent behaviour was monitored by radio‐tracking, and energy expenditure was measured using the doubly labelled water technique.

4. Robins with high overnight energy expenditures (= ‘negative’ body‐state; chilled) were less likely to initiate vocal behaviour, and less likely to respond to the song or calls of conspecifics than those with low overnight expenditures (= ‘positive’ body‐state; warmed).

5. Chilled birds moved around their territories at almost twice the rate of warmed birds, and had significantly higher daytime energy expenditures.

6. We concluded that behaviour, including vocalizations and activity levels, and energy expenditures of robins, were sensitive to manipulations of body‐state.

7. These behaviours are interpreted as adaptive responses to restore condition, while minimizing the risk of mortality from predation and starvation. Our results were consistent with the Balanced Effort Hypothesis, entailing an increase in energy expenditure on foraging and a reduction in expenditure on non‐maintenance activities.

8. We suggest that inter‐individual differences in body‐state may be a key cause of previously unexplained variation in daily energy expenditure.
Apparent inferiority of first‐time breeders in the kittiwake: the role of heterogeneity among age classes
Authors: Cam Emmanuelle , Monnat Jean‐Yves
Published: March 2003

1. Many studies have provided evidence that first‐time breeders have a lower survival, a lower probability of success, or of breeding, in the following year. Hypotheses based on reproductive costs have often been proposed to explain this. However, because of the intrinsic relationship between age and experience, the apparent inferiority of first‐time breeders at the population level may result from selection, and experience may not influence performance within each individual. In this paper we address the question of phenotypic correlations between fitness components. This addresses differences in individual quality, a prerequisite for a selection process to occur. We also test the hypothesis of an influence of experience on these components while taking age and reproductive success into account: two factors likely to play a key role in a selection process.

2. Using data from a long‐term study on the kittiwake, we found that first‐time breeders have a lower probability of success, a lower survival and a lower probability of breeding in the next year than experienced breeders. However, neither experienced nor inexperienced breeders have a lower survival or a lower probability of breeding in the following year than birds that skipped a breeding opportunity. This suggests heterogeneity in quality among individuals.

3. Failed birds have a lower survival and a lower probability of breeding in the following year regardless of experience. This can be interpreted in the light of the selection hypothesis. The inferiority of inexperienced breeders may be linked to a higher proportion of lower‐quality individuals in younger age classes. When age and breeding success are controlled for, there is no evidence of an influence of experience on survival or future breeding probability.

4. Using data from individuals whose reproductive life lasted the same number of years, we investigated the influence of experience on reproductive performance within individuals. There is no strong evidence that a process operating within individuals explains the improvement in performance observed at the population level.
Non‐linear transmission and simple models for bovine tuberculosis
Authors: Barlow N. D.
Published: March 2003

1. A new model is presented for a possum–tuberculosis (TB) system (Trichosurus vulpecula–Mycobacterium bovis) that is both realistic and parsimonious. The model includes a phenomenological treatment of heterogeneity of risk for susceptible hosts, similar to that used in insect host–parasitoid systems.

2. Parameter values for the model reflect current knowledge and differ significantly from those in other recent models of this system. Associated with these structural and parametric changes are substantially different predictions for the dynamics and control of TB in possums.

3. The model predictions include (i) only limited host suppression due to the disease (< 10%, cf. several earlier simple models for TB in both possums and badgers); (ii) asymptotically stable disease dynamics (cf. homogeneous‐mixing models that predict either extremely weak stability such that disease fails to recover when host density is temporarily reduced, or oscillatory behaviour and potential elimination of disease following such a perturbation); (iii) TB that is harder to control than in the homogeneous‐mixing model equivalents, in line with practical experience; and (iv) a threshold host density for disease elimination that differs substantially from the host equilibrium density in the presence of disease.

4. Homogeneous‐mixing models are unable to reproduce this behaviour, whatever parameter values are chosen. Heterogeneous‐mixing models with non‐linear transmission may therefore be worth consideration in other endemic wildlife disease systems, as is now commonplace for insect–parasitoid and insect–pathogen ones.
Spatial perturbation caused by a badger (Meles meles) culling operation: implications for the function of territoriality and the control of bovine tuberculosis (Mycobacterium bovis)
Authors: Tuyttens F. A. M. , Delahay R. J. , Macdonald D. W. , Cheeseman C. L. , Long B. , Donnelly C. A.
Published: March 2003

1. The spatial organization of a badger population (North Nibley) is described before and after it was subjected to a UK Ministry of Agriculture, Fisheries and Food badger removal operation (BRO) intended to control bovine tuberculosis. Comparison is made with an undisturbed badger population (Woodchester Park).

2. The Woodchester Park population was organized in group territories with clearly defined boundaries that remained stable during the 3 years of study (1995–97). In North Nibley, however, the badgers' spatial organization was severely perturbed in the first year and, to a lesser extent, also in the second year after the BRO, with badgers using latrines further away from their setts. This resulted in enlarged social group ranges that were difficult to define and overlapped considerably.

3. The disturbance was observed in the removal groups, those immediately adjacent, as well as those at a distance of one or two social groups from the removal area, with an unexpected indication that the latter groups may have been the most affected.

4. The apparent increase in the size of the group ranges in North Nibley was likely to have been caused by an increased proportion of badgers making extra‐group excursions in the aftermath of the BRO.

5. Initial recolonization was almost exclusively by females.

6. Although such perturbation might be expected to facilitate disease transmission between badger social groups, there was no evidence that any infectious animals had survived the BRO. However, there were further cattle breakdowns in the area.

7. The behaviour of badgers after the BRO also provided an opportunity to test predictions made by competing hypotheses about the main determinants of the badger's socio‐spatial behaviour.
The role of shared parasites in the exclusion of wildlife hosts:Heterakis gallinarumin the ring‐necked pheasant and the grey partridge
Authors: Tompkins D. M. , Greenman J. V. , Robertson P. A. , Hudson P. J.
Published: March 2003

1. A two‐host shared‐macroparasite model was parameterized from the results of infection and transmission experiments, to investigate whether apparent competition between the ring‐necked pheasant (Phasianus colchicus) and the grey partridge (Perdix perdix), mediated via the shared nematodeHeterakis gallinarum,could theoretically cause partridge exclusion.

2. Both the model created and the experiments conducted show that the bulk ofH. gallinaruminfection to partridges, when they occur in the same locations as pheasants, will be from the pheasants and not from the partridges themselves. This is due toR0for the parasite being 1·23 when infecting pheasants, but only 0·0057 when infecting partridges. Thus, when the pheasant is present in the model the partridge population is impacted by the shared parasite but, when the pheasant is absent, the parasite is lost from the system.

3. Based on best available parameter estimates, the observed impact ofH. gallinarumon the grey partridge may be sufficient to cause exclusion when the pheasant is present in the model. This supports the hypothesis that the UK grey partridge decline observed over the past 50 years may be partly due to apparent competition with pheasants.

4. Habitat separation between the two host species, where it decreases the rate ofH. gallinarumtransmission from the pheasant to the partridge, may allow them to co‐exist in the field in the presence of the parasite. We predict, however, that grey partridge exclusion would still occur if separation was less than 43%.
Quantitative webs as a means of assessing the impact of alien insects
Authors: Schönrogge K. , Crawley M. J.
Published: March 2003

1.We use quantitative linkage webs to investigate the impact of alien gall wasps on community structure. Britain has been invaded by four alien species of cynipid gallwasp,Andricus corruptrix, A. lignicola, A. kollari and A. quercuscalicis, over the last 150 years. To date, Britain can be divided into four zones from the north to the south with one, two, three and four invading species established in each zone.

2.The four species are naturalized in their new ranges and are locally the most abundant cynipid species, especially in their spring (sexual) generations. Like the native cynipid species they showed dramatic changes (up to three orders of magnitude) in density between generations, and the dominance structure of alien and native host species changed radically from generation to generation.

3.All four invading cynipid species were attacked by native parasitoid species. Using quantified linkage webs, we assess the contribution made by individual host gall species to each parasitoids population size. Although the parasitoid species have been described as broadly polyphagous, suggesting that the aliens should be richly linked with the native cynipid communities, we found that the galls of the invading species have become the main, and in a few cases the sole, contributors to local parasitoid populations, indicating major host shifts by the parasitoid species.

4.Within generations we found very little overlap among the parasitoid and inquiline communities associated with native and alien galls within generations. Similarly, the quantification of indirect interactions among cynipids between generations suggests that parasitoids and inquilines are not main factors in the dynamics of local cynipid communities. The recruitment of parasitoids and inquilines by the invading cynipid species is therefore unlikely to have a strong affect on native cynipid species.
Size distribution dynamics for a marine sessile organism with space‐limitation in growth and recruitment: application to a coral population
Authors: Muko Soyoka , Sakai Kazuhiko , Iwasa Yoh
Published: March 2003

Corals are clonal organisms and show a plastic growth. We study a partial differential equation model for the dynamics of size distribution of corals and predict the trajectory of recovery after a catastrophic disturbance, such as the recent bleaching that killed most corals in southern Japan.

We assume that the mean growth rate of colony size, measured in projected area, is a linear function of colony size, and that the variance in growth rate is proportional to the size, which is consistent with the growth data of a coral Acropora hyacinthus Dana 1846.

The model incorporates the space‐limitation in colony growth and recruitment. The growth rate and recruitment rate are proportional to the fraction of free space within the local habitat.

In many corals, including A. hyacinthus, recruitment occurs in a short period once a year. However, our model illustrates that the colony size distribution does not show distinguishable cohorts since the observed variance in growth rate is large. The model with discrete settlement and a large variance in growth rate results in size distributions that are very well approximated by an explicitly soluble model with constant recruitment and no growth variance.

When mortality is low, the dynamics of size distribution show two different phases in the recovery process. In the first phase, size distribution is determined by recruitment and growth, and can be predicted well by the case without mortality. After free space is depleted, recruitment and growth slow down and become balanced with mortality. The equilibrium size distribution is controlled by all the three processes. Both for the transient and the equilibrium size distribution, the average colony size increases with growth rate but decreases with recruitment rate.

Strongly skewed colony‐size distributions in which small size classes have the largest numbers are generated for a wide range of parameters by the space‐limitation in growth, even without partial death of colonies.
Numerical fluctuations in the northern short‐tailed shrew: evidence of non‐linear feedback signatures on population dynamics and demography
Authors: Lima Mauricio , Merritt Joseph F. , Bozinovic Francisco
Published: March 2003

We studied a fluctuating population of the northern short‐tailed shrew (Blarina brevicauda) in the Appalachian Plateau Province of Pennsylvania, USA, spanning 21 years of monitoring. We analysed the pattern of annual temporal variation fitting both time‐series models and capture–mark–recapture (CMR) statistical models for survival and recruitment rates.

 We determined that non‐linear first‐order models explain almost 80% of the variation in annual per capita population growth rates. In particular, a non‐linear self‐excited threshold autoregressive (SETAR) model describes the time‐series data well. Average snowfall showed positive and non‐linear effects on population dynamics.

 The CMR statistical models showed that a non‐linear threshold model with strong effects of population density was the best one to describe temporal variation in survival rates. On the other hand, population density or climatic variables did not explain temporal variation in recruitment rates. Survival rates were high during the study period. Weekly changes in population size attributable to new recruits entering in the population fluctuate between 21% and 0%, while the changes in population size related to survival fluctuate between 79% and 100%.

 Two important results arise from this study. First, non‐linear models with first‐order feedback appear to capture the essential features of northern short‐tailed shrew dynamics and demography. Secondly, climate effects represented by snowfall appear to be small and non‐linear on this insectivore. The population dynamics of this shrew in the Appalachian Plateau are determined apparently by a strong non‐linear first‐order feedback process, which is related to survival rates.

 This study links population dynamics and demography by detecting the underlying demographic mechanisms driving population dynamics. The feedback structure of this shrew suggests the existence of population dynamics dominated by intraspecific competitive interactions, such as aggression, solitary nesting, non‐overlapping home ranges and territoriality.
The effects of cowpox virus on survival in natural rodent populations: increases and decreases
Authors: Telfer Sandra , Bennett Malcolm , Bown Kevin , Cavanagh Rachel , Crespin Laurent , Hazel Sarah , Jones Trevor , Begon Michael
Published: March 2003

The effect of cowpox virus on survival in two rodent hosts was investigated using nearly 4 years of longitudinal data from two sites.

We investigated whether an individual's probability of infection influenced the probability of surviving the next month. We also investigated the effect at the population level, examining whether, in addition to seasonal effects, changes in cowpox prevalence explained further temporal variation in survival rates.

In bank voles, but not wood mice, individuals with high probabilities of infection survived better than uninfected animals.

At the level of the population, the effect of infection on survival varied through the year in both species. Survival rates in late summer increased with cowpox prevalence, whilst survival rates in winter decreased with cowpox prevalence.

We discuss why parasites such as cowpox virus may increase or decrease host survival and why the effect may depend on the time of year.
A comparison of the power of categorical and correlational tests applied to community ecology data from gradient studies
Authors: Somerfield P. J. , Clarke K. R. , Olsgard F.
Published: March 2003

Where gradients exist it is possible for a global test of community change to fail to achieve significance even though pairwise tests between groups of samples from opposite ends of gradients reveal significant differences. This study examines the power of alternative tests in situations where spatial (or temporal) gradients exist.

Data from an oilfield survey in the Norwegian sector of the North Sea are used to examine the power of two types of test. There is no theoretical statistical framework with which to examine the formal power of the non‐parametric multivariate tests. A univariate analogue is used to demonstrate the behaviour and relative power of linear regression andanovato detect different strengths of gradients.

Two multivariate tests are then contrasted using simulations.anosim(Analysis of Similarities) is a categorical analysis and, for an ecological matrix of pairwise dissimilarities among all samples, tests null hypotheses of theanovatype: H0: There are no differences between groups of samples. This test is compared withrelate, a non‐parametric Mantel test which is used here to test the null hypothesis: H0: The dissimilarities among samples in the ecological matrix are not (monotonically) correlated with corresponding ‘model’ distances between samples along the gradient.

It is demonstrated that, where a gradient is present in the data, an appropriate univariate test based on linear regression always has greater power thananovato detect it. This is especially true where the gradient is weak and/or replication is low.

It is shown that the multivariate tests behave in a similar way to their univariate analogues. Where there is a detectable gradient in the data the correlative test (relate) has greater potential to detect it than does the categorical testanosim. The differences in power are especially apparent at low to intermediate strengths of gradient. Distributing replicates among more groups decreases the power of both tests, but especiallyanosim, to detect a constant gradient effect.

Although demonstrated using a practical application, the findings presented here are general in nature and applicable to any ecological investigation in which a gradient in response may be hypothesized.