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Most birds, unlike reptiles, lay eggs successively to form a full clutch. During egg-laying, birds are highly secretive and prone to disturbance and predation. Using multisensor data loggers, we show that average daily body temperature during egg-laying is significantly increased (1 °C) in wild eider ducks ( Somateria mollissima ). Strikingly, this increase corresponds to the annual maximum body temperature (40.7 °C), representing a severe annual thermogenic challenge. This egg-laying-induced rise in body temperature may prove to be a common feature of wild birds and could be caused by habitat-related thermoregulatory adjustments and hormonal modulation of reproduction. We conclude our findings with new perspectives of the benefits of high body temperature associated with egg-laying of birds and the potential effect of heat stress that may occur with the future advent of heatwaves.

Because cohabiting unions are, on average, less stable than marriages, the diffusion of childbearing within cohabitation could lead to an overall increase in family instability. The possibility that cohabiting families become increasingly stable throughout the diffusion process is, however, seldom studied. Taking the point of view of Canadian children, we investigated the differential effect of the diffusion of childbearing within cohabitation on married and cohabiting parents' risks of separation. We were especially attentive to the functional form of relationships and to the specific role of selection and causal mechanisms. We used Cox regressions to estimate children's hazards of parental separation up to age 6 according to the prevalence of childbearing within cohabitation in their province and cohort. The analysis is conducted by merging individual survey data on Canadian children born from 1989 to 2004 (NLSCY; n=24,175) with contextual data from various sources. As childbearing within cohabitation increased in Canadian provinces, cohabiting families remained less stable than married ones, but the stability levels of both converged. The stability gap was only partially explained by the selection of more separation-prone parents into cohabitation; the remaining gap could be associated with the normative context in which family formation occurs.

Since 1990 mortality and morbidity decline has been more extensive for some conditions prevalent in low-and middle-income countries than for others. One reason may be differences in the effectiveness of global health networks, which have proliferated in recent years. Some may be more capable than others in attracting attention to a condition, in generating funding, in developing interventions and in convincing national governments to adopt policies. This article introduces a supplement on the emergence and effectiveness of global health networks. The supplement examines networks concerned with six global health problems: tuberculosis (TB), pneumonia, tobacco use, alcohol harm, maternal mortality and newborn deaths. This article presents a conceptual framework delineating factors that may shape why networks crystallize more easily surrounding some issues than others, and once formed, why some are better able than others to shape policy and public health outcomes. All supplement papers draw on this framework. The framework consists of 10 factors in three categories: (1) features of the networks and actors that comprise them, including leadership, governance arrangements, network composition and framing strategies; (2) conditions in the global policy environment, including potential allies and opponents, funding availability and global expectations concerning which issues should be prioritized; (3) and characteristics of the issue, including severity, tractability and affected groups. The article also explains the design of the project, which is grounded in comparison of networks surrounding three matched issues: TB and pneumonia, tobacco use and alcohol harm, and maternal and newborn survival. Despite similar burden and issue characteristics, there has been considerably greater policy traction for the first in each pair. The supplement articles aim to explain the role of networks in shaping these differences, and collectively represent the first comparative effort to understand the emergence and effectiveness of global health networks.

Seabirds exhibit considerable adjustment capacity to cope with environmental changes during the breeding season and to maximize lifetime reproductive output. For example, divorce has been proposed to be an adaptive behavioral strategy in social monogamous species, as a response to poor conditions and low breeding success. Here, we studied divorce at the population and individual levels in northern gannets ( Morus bassanus , hereafter gannets) nesting on Bonaventure island (Quebec, Canada). At the population level, we used Granger’s method for detecting and quantifying temporal causality between time series (from 2009 to 2019) of divorce rate and breeding success of gannets ( n = 809) and we evaluated the relationship between breeding success and biomass of their two principal prey (Atlantic mackerel, Scomber scombrus , and Atlantic herring, Clupea harengus ). Our results indicated that breeding success is mainly influenced by the spawning-stock biomass of Atlantic mackerel, and a decrease in breeding success is followed by an increase in divorce rate with a 1-year lag. However, the effect of the interaction between breeding success and year on the proportion of individuals that divorced showed significant inter-annual variation. At the individual level, our results support the adaptive strategy hypothesis of divorce. Indeed, gannets that changed partners did so following a reproductive failure, and there was an increase in breeding success 1 year following the divorce. Being central place foragers, opportunities for dispersal and adaptation are often limited for breeding seabirds in a context of low food abundance. We suggest that behavioral flexibility expressed as divorce would be an efficient short-term strategy for maintaining reproductive performance.

80% of the world's undernourished children live in just 20 countries. Intensified nutrition action in these countries can lead to achievement of the first Millennium Development Goal (MDG) and greatly increase the chances of achieving goals for child and maternal mortality (MDGs 4 and 5). Despite isolated successes in specific countries or for interventions—eg, iodised salt and vitamin A supplementation—most countries with high rates of undernutrition are failing to reach undernourished mothers and children with effective interventions supported by appropriate policies. This paper reports on an assessment of actions addressing undernutrition in the countries with the highest burden of undernutrition, drawing on systematic reviews and best-practice reports. Seven key challenges for addressing undernutrition at national level are defined and reported on: getting nutrition on the list of priorities, and keeping it there; doing the right things; not doing the wrong things; acting at scale; reaching those in need; data-based decisionmaking; and building strategic and operational capacity. Interventions with proven effectiveness that are selected by countries should be rapidly implemented at scale. The period from pregnancy to 24 months of age is a crucial window of opportunity for reducing undernutrition and its adverse effects. Programme efforts, as well as monitoring and assessment, should focus on this segment of the continuum of care. Nutrition resources should not be used to support actions unlikely to be effective in the context of country or local realities. Nutrition resources should not be used to support actions that have not been proven to have a direct effect on undernutrition, such as stand-alone growth monitoring or school feeding programmes. In addition to health and nutrition interventions, economic and social policies addressing poverty, trade, and agriculture that have been associated with rapid improvements in nutritional status should be implemented. There is a reservoir of important experience and expertise in individual countries about how to build commitment, develop and monitor nutrition programmes, move toward acting at scale, reform or phase-out ineffective programmes, and other challenges. This resource needs to be formalised, shared, and used as the basis for setting priorities in problem-solving research for nutrition.

Although there is a consensus about the evolutionary drivers of animal migration, considerable work is necessary to identify the mechanisms that underlie the great variety of strategies observed in nature. The study of differential migration offers unique opportunities to identify such mechanisms and allows comparisons of the costs and benefits of migration. The purpose of this study was to compare the characteristics of short and long-distance migrations, and fitness consequences, in a long-lived seabird species. We combined demographic monitoring (survival, phenology, hatching success) of 58 Northern Gannets (Morus bassanus) breeding on Bonaventure Island (Canada) and biologging technology (Global Location Sensor or GLS loggers) to estimate activity and energy budgets during the non-breeding period for three different migration strategies: to the Gulf of Mexico (GM), southeast (SE) or northeast (NE) Atlantic coast of the U.S. Survival, timing of arrival at the colony and hatching success are similar for short (NE, SE) and long-distance (GM) migrants. Despite similar fitness consequences, we found, as expected, that the overall energetic cost of migration is higher for long-distance migrants, although the daily cost during migration was similar between strategies. In contrast, daily maintenance and thermoregulation costs were lower for GM migrants in winter, where sea-surface temperature of the GM is 4-7o C warmer than SE and NE. In addition, GM migrants tend to fly 30 min less per day in their wintering area than other migrants. Considering lower foraging effort and lower thermoregulation costs during winter for long-distance migrants, this suggests that the energetic benefits during the winter of foraging in the GM outweigh any negative consequences of the longer-distance migration. These results support the notion that the costs and benefits of short and long-distance migration is broadly equal on an annual basis, i.e. there are no apparent carry-over effects in this long-lived bird species, probably because of the favourable conditions in the furthest wintering area.

An important cause of stunting is limited consumption of complementary foods, in terms of both quantities and nutrients. Although existing studies show a positive association between fathers' engagement and children's diet, programmes designed to improve complementary feeding practices often only target mothers. In response to this, maternal behaviour change communication (BCC), paternal BCC and food voucher programmes were designed and implemented in Ethiopia using a clustered randomized controlled trial design. The paternal BCC programme included gender‐equal messages to increase fathers' participation in childcare, household labour and decision making. The research reported in this paper is an examination of the BCC programmes, characterizing the behavioural, normative and control beliefs of both mothers and fathers in BCC households compared to those in control households. In this study, a total of 40 participants were included, with 13 mother–father pairs in the BCC + food voucher group, and seven pairs in the control group. Each participant was interviewed separately. We found that BCC mothers showed more gender‐equal tendencies than the control mothers despite being more rural in location. By contrast, the beliefs of BCC and control fathers were similar overall, suggesting men are more resistant to gender‐equal BCC. More work is needed to develop and test effective methods for changing fathers' beliefs and practices. BCC programmes foster gender‐equal beliefs among mothers, promoting shared household labour and decision making. Fathers show resistance to altering traditional gender roles, yet acknowledge that decision making should be based on expertise, indicating potential for gradual change towards equality in domestic responsibilities. Key messages Mothers in behaviour change communication (BCC) group mothers held more gender‐equal beliefs than control mothers, while BCC and control fathers shared similar views, suggesting a male resistance to gender equality. Mothers found fathers' involvement in childcare socially acceptable but often perceived them as inexperienced, which limited their participation. Control mothers' traditional view on household chores maintained the conventional labour division, influencing fathers' involvement. Fathers typically resisted maternal control of resources; however, they agreed that the more knowledgeable should lead decision‐making. BCC mothers showed greater confidence in making household decisions as effectively as fathers.

Connectivity models are useful tools that improve the ability of researchers and managers to plan land use for conservation and preservation. Most connectivity models function in a point-to-point or patch-to-patch fashion, limiting their use for assessing connectivity over very large areas. In large or highly fragmented systems, there may be so many habitat patches of interest that assessing connectivity among all possible combinations is prohibitive. To overcome these conceptual and practical limitations, we hypothesized that minor adaptation of the Circuitscape model can allow the creation of omnidirectional connectivity maps illustrating flow paths and variations in the ease of travel across a large study area. We tested this hypothesis in a 24,300 km(2) study area centered on the Montérégie region near Montréal, Québec. We executed the circuit model in overlapping tiles covering the study region. Current was passed across the surface of each tile in orthogonal directions, and then the tiles were reassembled to create directional and omnidirectional maps of connectivity. The resulting mosaics provide a continuous view of connectivity in the entire study area at the full original resolution. We quantified differences between mosaics created using different tile and buffer sizes and developed a measure of the prominence of seams in mosaics formed with this approach. The mosaics clearly show variations in current flow driven by subtle aspects of landscape composition and configuration. Shown prominently in mosaics are pinch points, narrow corridors where organisms appear to be required to traverse when moving through the landscape. Using modest computational resources, these continuous, fine-scale maps of nearly unlimited size allow the identification of movement paths and barriers that affect connectivity. This effort develops a powerful new application of circuit models by pinpointing areas of importance for conservation, broadening the potential for addressing intriguing questions about resource use, animal distribution, and movement.

Undemutrition is the single largest contributor to the global burden of disease and can be addressed through a number of highly efficacious interventions. Undemutrition generally has not received commensurate attention in policy agendas at global and national levels, however, and implementing these efficacious interventions at a national scale has proven difficult. This paper reports on the findings from studies in Bangladesh, Bolivia, Guatemala, Peru and Vietnam which sought to identify the challenges in the policy process and ways to overcome them, notably with respect to commitment, agenda setting, policy formulation and implementation. Data were collected through participant observation, documents and interviews. Data collection, analysis and synthesis were guided by published conceptual frameworks for understanding malnutrition, commitment, agenda setting and implementation capacities. The experiences in these countries provide several insights for future efforts: (a) high-level political attention to nutrition can be generated in a number of ways, but the generation of political commitment and system commitment requires sustained efforts from policy entrepreneurs and champions; (b) mid-level actors from ministries and external partners had great difficulty translating political windows of opportunity for nutrition into concrete operational plans, due to capacity constraints, differing professional views of undemutrition and disagreements over interventions, ownership, roles and responsibilities; and (c) the pace and quality of implementation was severely constrained in most cases by weaknesses in human and organizational capacities from national to frontline levels. These findings deepen our understanding of the factors that can influence commitment, agenda setting, policy formulation and implementation. They also confirm and extend upon the growing recognition that the heavy investment to identify efficacious nutrition interventions is unlikely to reduce the burden of undemutrition unless or until these systemic capacity constraints are addressed, with an emphasis initially on strategic and management capacities.

While some migratory birds perform non-stop flights of over 11 000 km, many species only spend around 15% of the day in flight during migration, posing a question as to why flight times for many species are so short. Here, we test the idea that hyperthermia might constrain flight duration (FD) in a short-distance migrant using remote biologging technology to measure heart rate, hydrostatic pressure and body temperature in 19 migrating eider ducks (Somateria mollissima), a short-distance migrant. Our results reveal a stop-and-go migration strategy where migratory flights were frequent (14 flights day−1) and short (15.7 min), together with the fact that body temperature increases by 1°C, on average, during such flights, which equates to a rate of heat storage index (HSI) of 4°C h−1. Furthermore, we could not find any evidence that short flights were limited by heart rate, together with the fact that the numerous stops could not be explained by the need to feed, as the frequency of dives and the time spent feeding were comparatively small during the migratory period. We thus conclude that hyperthermia appears to be the predominant determinant of the observed migration strategy, and suggest that such a physiological limitation to FD may also occur in other species. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’.