Summary 1.Behaviour-based models of animal population dynamics provide ecologists with a powerful tool for predicting the response of such populations to both natural and human-induced environmental changes. 2. We developed this approach by addressing two outstanding issues in the application of such models: the need to adopt a large-scale spatially explicit approach, and the need to consider the year-round dynamics of animal populations. 3. Spatially explicit, year-round, behaviour-based models of two populations of arctic-breeding geese, the Svalbard population of the barnacle goose Branta leucopsis and the dark-bellied race of the brent goose Branta bernicla, were developed. Both populations have been the subject of serious conservation concern and are currently a source of increasing con¯ict with agricultural interests. 4. There was generally good agreement between empirically derived and modelgenerated density-dependent functions, and of seasonal patterns of the distribution and movement of populations within and between sites, and of energy reserve levels within a population. 5. Sensitivity analyses, however, highlighted the importance of accurate parameter estimation with respect to the predictions of such models, and the potential¯aws in the predictions of existing models that have not adopted a spatially explicit approach when dealing with wide-ranging migratory populations. 6. The eect of the removal of a given area of habitat on both populations was predicted to vary depending upon the spatial con®guration of the change. This further emphasizes the need for a spatially explicit approach. 7. Both barnacle goose and brent goose populations were predicted to decline following habitat loss in their winter or spring-staging sites. Simulations suggested that barnacle geese might be less vulnerable to winter habitat loss than brent geese. This re¯ected the relative strengths of the density-dependence of productivity and winter mortality in the two models and provided a clear illustration of the need for a year-round approach to animal population dynamics. 8. We believe that these models, and this approach to understanding the population dynamics of long-distance migrants, will be bene®cial in attempting to answer the increasingly urgent and frequent requests to predict the response of such populations to environmental change.

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The case of a 14-month-old boy with vitamin D deficiency rickets as a result of unsupervised dietary manipulation in the context of cow's milk allergy is presented. Adequate supervision by a qualified dietician, coupled with appropriate supplementation, is essential if nutritional compromise is to be avoided in children with food allergy.

Research on relationship aspects in residential treatment of criminal young persons has largely been neglected despite the general finding in treatment research that such aspects have a large bearing on outcome. In this article, two studies of associations between relationship aspects and outcome in this treatment context are presented. In one of them, two treatment units practicing Aggression Replacement Training and CBT-techniques and 2 U with more conventional, relationally oriented treatment approaches were studied using process questionnaires and interviews. In the other study, adolescents who had been sentenced to treatment were interviewed about treatment experiences 1 year after release. Despite considerable attrition, several interesting findings were noted: The boys' alliance ratings were associated with the collaborative aspect of the staff's alliance ratings, but not with the bond aspect; warm and close staff feelings were related to negative outcome and the boys' conceptions of the treatment model but not of the relationship with the staff was associated with positive outcome. The results suggest that a distinction should be made between a mutual bond aspect of the staffÀboy relationship that was not related to outcome and a collaborative aspect which was related to outcome.

Background: Elimination diets required for the management of food allergies increase the risk for poor growth in children. Currently, no worldwide data exist on this topic and limited published data exist on the impact of atopic comorbidity, type of allergy and foods eliminated on growth. We therefore set out to perform a worldwide survey on growth and impacting factors in food allergic children. Methods: A prospective growth survey was performed of children (aged 0-16 years) on an elimination diet with confirmed immunoglobulin (Ig)E and non-IgE mediated food allergies. Data collected included: weight-for-age, weight-for-height, height-for-age, head circumference, body mass index, type of food allergy and eliminated foods, allergic comorbidities and replacement milk/breast milk. Multivariable regression analysis was used to establish factors that affected growth. Results: Data from 430 patients from twelve allergy centres were analysed: median age at diagnosis and data collection was 8 months and 23 months, respectively. Pooled data indicated that 6% were underweight, 9% were stunted, 5% were undernourished and 8% were overweight. Cow's milk elimination lead to a lower weight-for-height Z-scores than other food eliminations and mixed IgE and non-IgE mediated allergy had lower height-forage Z-scores than IgE mediated allergy. Children with only non-IgE mediated allergies had lower weight-for-height and body mass index. Atopic comorbidities did not impact on growth. Conclusions: Stunting is more common in children with food allergies than low weight. Children particularly at risk of poor growth are those with non-175

We present a theoretical investigation of divorce. Arguments are couched in terms of birds, but should be applicable to other groups of organisms. We model a population in which there is a range of both male and female qualities, and decisions on whether to divorce are made by both members of a breeding pair. The reproductive success of a pair is additive in male and female qualities in the baseline case, but we also consider the e¡ect of quality interactions. The availability of new mates depends on the divorce strategy of all population members. We allow for the possibility that mate choice is associative in quality, although we do not explicitly model the mate choice process. Using a game-theoretical model which incorporates these factors we investigate the following issues: the form of the evolutionary stable strategy, and the implications of this strategy for quality correlations in breeding pairs and for the distribution of qualities among unpaired individuals; divorce rates, reproductive success and mate quality changes over the lifetime of an individual, and the dependence of these qualtities on the individual's quality; mean population divorce rates and their dependence on costs of divorce, longevity and the extent of quality variation in the two sexes; initiators of divorce and reproductive success before and after divorce.

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This article reports a study where aggression replacement training (ART), combined with token economy, was compared with relationally oriented treatment at four residential treatment units in a nonrandomized design. In all, 57 adolescents in the ages between 16 and 19 participated. Outcome was measured as weighted indices of sentences and police suspicion reports. The results show no differences between the treatment models. In a separate analysis, the hypotheses were tested that those adolescents would relapse less frequently who admitted their crimes at intake or who could talk about guilt for their criminal acts. These hypotheses were refuted as main effects, but an interaction effect was found that suggests that adolescents with less consciousness of guilt got better results at the ART institutions. Case descriptions suggest that a more individualized approach to treatment, where ART is used for those adolescents who are motivated for it, would give better results.