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1. Determining the precise timing and location of major demographic bottlenecks, such as periods of low survival, is key to identifying ecological causes of variation in population growth rate. Such understanding is key to designing efficient and effective mitigation. 2. In a protected population of red-billed chough Pyrrhocorax pyrrhocorax on Islay, Scotland, variation in population growth rate largely reflects among-year variation in first-year survival. First-year survival was unprecedentedly low during 2007–2010, threatening population viability. 3. We used colour-ring resightings to estimate monthly survival probabilities (Φm) throughout the first year from fledging for eight chough cohorts (totalling 519 individuals) representing the full observed range of variation in first-year survival. We thereby identify the time and location of recent low survival. 4. On average across all cohorts, Φm varied among months, being low during the first month after ringing (May–June, accounting for c. 24% of all first-year mortality) and high during the last 4 months of the first year (January–May, accounting for c. 6% of all first-year mortality). Most mortality (c. 70%) occurred after fledglings dispersed from natal territories. 5. The 2007–2009 cohorts experienced low Φm during July–December. This represents an additional low survival period compared to previous cohorts rather than decreased Φm across all months or further decreases through periods when Φm was low across all cohorts. 6. Synthesis and applications. These data have general relevance in showing that dramatically low annual survival, which needs to spark rapid management action, can reflect different and unanticipated periods of low survival rather than exaggeration of typical variation. With specific regard to conserving Islay’s chough population, our data show that sub-adult survival has recently been low during July–December, probably reflecting conditions on key grassland foraging areas. Managers aiming to

1. Understanding the degree to which reproductive success varies with an individual’s age and lifespan, and the degree to which population-level variation mirrors individual-level variation, is central to understanding life-history evolution and the dynamics of age-structured populations. We quantified variation in the survival probability of offspring, one key component of reproductive success and fitness, in relation to parent age and lifespan in a wild population of red-billed choughs (Pyrrhocorax pyrrhocorax). 2. On average across the study population, the first-year survival probability of offspring decreased with increasing parent age and lifespan; offspring of old parents were less likely to survive than offspring of young parents, and offspring of long-lived parents were less likely to survive than offspring of short-lived parents. 3. However, survival did not vary with parent age across offspring produced by groups of parents that ultimately had similar lifespans. 4. Rather, across offspring produced by young parents, offspring survival decreased with increasing parent lifespan; parents that ultimately had long lifespans produced offspring that survived poorly, even when these parents were breeding at young ages. 5. The average decrease in offspring survival with increasing parent age observed across the population therefore reflected the gradual disappearance of short-lived parents that produced offspring that survived well, not age-specific variation in offspring survival within individual parents. 6. The negative correlation between offspring survival and maternal lifespan was strongest when environmental conditions meant that offspring survival was low across the population. 7. These data suggest an environment-dependent trade-off between parent and offspring survival, show consistent individual variation in the resolution of this trade-off that is set early in a parent’s life, and demonstrate that such structured life-history variation can generate spu

This report summarises the results of a Knowledge Transfer Research Project that was undertaken by Dr Jane Reid (University of Aberdeen), Professor Pat Monaghan, (University of Glasgow), Dr Eric and Mrs Sue Bignal (Scottish Chough Study Group) and Dr Davy McCracken (Scottish Agricultural College). Dr Maria Bogdanova was employed as the postdoctoral research assistant on the project. The work was carried out in partnership with Scottish Natural Heritage (SNH) and the Royal Society for the Protection of Birds (RSPB). Funding was provided by a Knowledge Transfer Grant from the Natural Environment Research Council (NERC, PIs P. Monaghan & J. Reid), with matching partnership funding and in-kind support from SNH and RSPB. The overall aims of the project were to develop the scientific understanding of the population ecology of choughs on Islay, and to use this understanding to inform the development of appropriate conservation strategies and policies. The project built on existing long-term research on Islay’s choughs. It involved further analysis of long-term data, plus two years of intensive fieldwork designed to answer specific questions. The work aimed primarily to understand the ecology of choughs in their sub-adult years (ie, from fledging to breeding age). Survival from fledging to breeding is a key factor in causing population change. However, relatively little was previously known about the behaviour and ecology of choughs during this time. This report provides an overview of the results of the scientific study and focuses on presenting the scientific evidence on which resulting recommendations for chough conservation management on Islay are based. The report is written with the intention of presenting the results of the data analyses, and the rationale underlying those analyses, in a way that is accessible to non-specialists. Further details of analyses and technicalities are provided in published, peer-reviewed papers and/or are available on request. The report

This report summarises the results of a Knowledge Transfer Research Project that was undertaken by Dr Jane Reid (University of Aberdeen), Professor Pat Monaghan, (University of Glasgow), Dr Eric and Mrs Sue Bignal (Scottish Chough Study Group) and Dr Davy McCracken (Scottish Agricultural College). Dr Maria Bogdanova was employed as the postdoctoral research assistant on the project. The work was carried out in partnership with Scottish Natural Heritage (SNH) and the Royal Society for the Protection of Birds (RSPB). Funding was provided by a Knowledge Transfer Grant from the Natural Environment Research Council (NERC, PIs P. Monaghan & J. Reid), with matching partnership funding and in-kind support from SNH and RSPB. The overall aims of the project were to develop the scientific understanding of the population ecology of choughs on Islay, and to use this understanding to inform the development of appropriate conservation strategies and policies. The project built on existing long-term research on Islay’s choughs. It involved further analysis of long-term data, plus two years of intensive fieldwork designed to answer specific questions. The work aimed primarily to understand the ecology of choughs in their sub-adult years (ie, from fledging to breeding age). Survival from fledging to breeding is a key factor in causing population change. However, relatively little was previously known about the behaviour and ecology of choughs during this time. This report provides an overview of the results of the scientific study and focuses on presenting the scientific evidence on which resulting recommendations for chough conservation management on Islay are based. The report is written with the intention of presenting the results of the data analyses, and the rationale underlying those analyses, in a way that is accessible to non-specialists. Further details of analyses and technicalities are provided in published, peer-reviewed papers and/or are available on request. The report